Page 1
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smart USA
Introduction of the smart fortwo
Model Series 451
Introduction into Service Manual
SN_Typ 451_us.book Seite 1 Freitag, 30. November 2007 1:56 13
Page 3
Copyright
© smart USA, 2007
All rights reserved. Reproduction by any means,
electronic or mechanical, including photocopying,
recording, or by any information storage and retrieval
system or translation in whole or part is not permitted
without written authorization from the publisher.
Published by smart USA, 2007
Printed in U.S.A.
www.smartusa.com
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Page 4
Content
3
Introduction of the smart fortwo, Model Series 451
Preface 7
Complete vehicle
Overview 8
Technical data 10
Maintenance 13
Safety concept 17
Electrical system
On-board electrical system/power supply 20
Complete networking 22
Wiring harnesses 24
Diagnosis 26
SAM control unit 28
Engine M132
Engine description 30
Performance graph 30
Engine data 32
Valve assembly 33
Valve timing 34
Gasoline injection and ignition system 35
Belt drive 38
Cooling system 39
Engine mount 41
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Content
4
Introduction of the smart fortwo, Model Series 451
Fuel system
Fuel supply 42
Exhaust system
Overview 45
Secondary air injection 46
Automated manual transmission
Transmission description 47
Transmission data 48
Shift mechanism 49
Synchronization 54
Transmission control 55
Park pawl 61
Clutch 62
Chassis
Front axle 64
Rear axle 65
Rear module 66
Tire pressure monitor 67
Brakes 69
Steering 75
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Content
5
Introduction of the smart fortwo, Model Series 451
Body
Interior 82
Doors/flaps 86
Roof systems 90
Central locking 96
Anti-theft alarm system (ATA [EDW]) 99
Exterior lights 101
Audio system 102
Climate control 104
Customized Bodypanel System (CBS) 106
Seats 108
Supplemental restraint system 109
Body 113
Accessories
smart accessories 116
Index 120
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Page 7
Content
6
Introduction of the smart fortwo, Model Series 451
SN_Typ 451_us.book Seite 6 Freitag, 30. November 2007 1:56 13
Page 8
Preface
7
Introduction of the smart fortwo, Model Series 451
Dear reader,
This Introduction into Service Manual presents the
new smart fortwo in model series 451.
The purpose of this manual is to inform you of the
technical features of this new vehicle. This brochure
is intended to provide information for people
employed in service, maintenance and repair as well
as for aftersales staff.
In terms of the contents, the emphasis in this Introduction into Service manual is on presenting the major
assemblies and systems.
This Introduction into Service manual is not intended
as an aid for repairs or for the diagnosis of technical
problems. For such needs, more extensive information
is available in the Workshop Information System (WIS)
and in the Diagnosis Assistance System (DAS).
WIS is updated monthly. Therefore, the information
available there reflects the latest technical status.
This Introduction into Service Manual presents initial
information relating to the new smart fortwo in model
series 451 and, as such, is not stored in WIS. The
contents of this brochure are not updated. No provision is made for supplements.
We will publicize modifications and new features in the
relevant WIS documents. The information presented in
this Introduction into Service Manual may therefore
differ from the more up-to-date information found in
WIS.
All information relating to technical data, equipment
and options is valid as of the copy deadline in
September 2007 and may therefore differ from the
current production configuration.
smart USA aftersales
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Page 9
Overview
8
Complete vehicle
Introduction of the smart fortwo, Model Series 451
P00.10-4192-00
P00.10-4198-00
smart fortwo coupé
smart fortwo cabrio
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Page 10
Overview
Complete vehicle
9
Introduction of the smart fortwo, Model Series 451
Vehicle concept
Externally, the smart fortwo is immediately distinguishable by its compactness with the tridion safety
cell and its two-tone design. The smart fortwo is available in a variety of colors. The tridion safety cell in
black or silver can be combined with six different
basic colors.
The model series can be ordered as the smart fortwo
coupé or the smart fortwo cabrio.
Despite its compact appearance, the smart fortwo
provides the occupants with a generous amount of
legroom and sufficient trunk capacity.
The interior compartment has a classic design. The
instrument panel was designed with straight lines and
the colors have been kept refined. Repeated aluminum
accent trim on the air vents and the inside door
handles gives the interior design a harmonic yet
modern aspect.
Vehicle characteristics
• Overall vehicle exterior
External dimensions to suitably accommodate the
occupants and provide sufficient the trunk
capacity.
Plastic panoramic sunroof or full roof on the smart
fortwo coupé.
Tritop soft top on the smart fortwo cabrio.
• Overall vehicle interior
Numerous color and pattern variants in the
interior.
Ergonomic instrument cluster in the instrument
panel.
Clearly arranged and user-friendly center
console.
Rear-end door with integral stowage compartment
for the smart fortwo coupé or tight-fitting stowage
areas without retaining straps for the roof side
supports in the smart fortwo cabrio.
• Engine/injection system
3-cylinder gasoline engine with 52 kW.
Fuel injection system with Bosch Multi-PointInjection.
• Transmission
5-speed automated manual transmission AMT 2
(2nd generation).
• Suspension
MacPherson front suspension with torsion
stabilizer bars.
DeDion rear axle.
• Brake
Hydraulic 2-circuit brake system with ESP and TT
(front/rear) split, version 8.1 from Bosch.
• Steering
Equipped with rack-and-pinion steering as
standard.
Electromechanical power steering with active
steering centering and adaptation of the steering
forces available as special equipment.
• Maintenance
Maintenance concept: Maintenance service only
every two years, with only the Oil Service Plus once
a year in between.
Service flap at front for easy access to the
maintenance points.
• Safety
Restraint system with airbags and emergency
tensioning retractors.
Bodyshell made of high-strength steels.
Door reinforcements made of high-strength
steels.
Full-length knee guard for driver and passenger.
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Page 11
Technical data
10
Complete vehicle
Introduction of the smart fortwo, Model Series 451
P00.10-4259-00
Dimensions - smart fortwo coupé
48.0
50.0
27.7
28.7
106.1
15.9
73.5
16.7
24.4
19.7
39.7
21.0
11.5
21.0
54.5
61.4
69.0
50.5
60.7
Dimensions Unit smart fortwo coupé (model 451)
Vehicle length in (mm) 106.1 (2695)
Vehicle width in (mm) 61.4 (1559)
Vehicle height in (mm) 60.7 (1542)
Wheelbase in (mm) 73.5 (1867)
Front track width in (mm) 50.5 (1283)
Rear track width in (mm) 54.5 (1385)
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Page 12
Technical data
Complete vehicle
11
Introduction of the smart fortwo, Model Series 451
P00.10-4260-00
Dimensions - smart fortwo cabrio
48.0
50.0
27.7
28.7
106.1
15.9
73.5
16.7
24.4
19.7
39.7
21.0
11.5
21.0
54.5
61.4
69.0
50.5
60.7
Dimensions Unit smart fortwo cabrio (model 451)
Vehicle length in (mm) 106.1 (2695)
Vehicle width in (mm) 61.3 (1559)
Vehicle height in (mm) 60.7 (1542)
Wheelbase in (mm) 73.5 (1867)
Front track width in (mm) 50.5 (1283)
Rear track width in (mm) 54.5 (1385)
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Technical data
12
Complete vehicle
Introduction of the smart fortwo, Model Series 451
Models and major assemblies
Loads, weights and other data
smart fortwo Model Engine Transmission
smart fortwo coupé 451.331
132.910 (52 kW) 717.482
smart fortwo cabrio 451.431
Unit smart fortwo coupé smart fortwo cabrio
Powerplant kW 52 52
Permissible front axle load lb
(kg)
969
(440)
Permissible rear axle load lb
(kg)
1458
(660)
Curb weight as per DIN lb
(kg)
1652
(820)
1740
(840)
Permissible gross vehicle weight lb
(kg)
2247
(1050)
2247
(1050)
Payload lb
(kg)
595
(230)
507
(210)
of which max. in luggage compartment
lb
(kg)
110
(50)
Max. seating capacity 2
Luggage compartment volume
up to belt line
up to roof
in
3
(l)
in
3
(l)
7.8
(220)
12
(340)
Turning circle yd
(m)
9.57
(8.75)
Tank capacity/including reserve US gal
(l)
8.72/1.32
33/5
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Page 14
Maintenance
Complete vehicle
13
Introduction of the smart fortwo, Model Series 451
Ma xintenance concept
Consistent product development has enabled a
future-oriented servicing concept to be implemented
in model series 451.
The servicing concept of the smart fortwo has allowed
the service intervals to be extended significantly, as
shown below.
Maintenance intervals
* depending on first occurrence
smart fortwo kW Interval
Gasoline engine 52 Every 2 years or 20,000 miles*
Oil Service Plus
In combustion engines with a high engine output per
unit of displacement, the engine oil is subjected to
extreme loads. With 3.7 US qt (3.5 liters), the smart
fortwo has a relatively small quantity of engine oil,
meaning that it has to be replaced at regular
time/mileage intervals.
To help optimize operating costs, the "Oil Service
Plus" has been introduced, which is due every 10 000
miles or once per year. It comprises merely an engine
oil change and inspection of the safety-relevant
components and functions.
This servicing concept has benefits for both the
workshops and the customers:
• Customers have lower vehicle operating costs due
to the reduced maintenance costs as a whole. This
improves customer satisfaction.
• The workshops improve their competitiveness in
the servicing business especially. Longer-lasting
customer loyalty and better chances of follow-up
business are possible with this concept.
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Page 15
Maintenance
14
Complete vehicle
Introduction of the smart fortwo, Model Series 451
Maintenance interval display (WIA)
The maintenance interval display is located in the
multifunction display of the instrument cluster.
The maintenance intervals are indicated by the
lighting of one or two wrench symbols.
In addition, approximately one month in advance of a
scheduled service date the multifunction display
shows the remaining time (in days) until it is due. After
engine start the range (in miles) is displayed for about
ten seconds.
P54.32-5676-00
Instrument cluster
A1 Instrument cluster
A1p13 Multifunction display
i Note
When the Oil Service Plus or a maintenance service
has been performed, the maintenance interval
display can be reset to the starting distance on
the instrument cluster itself or via STAR
DIAGNOSIS.
(See WIS for a detailed description.)
Meaning of wrench symbols:
• 1 wrench means Oil Service Plus
• 2 wrenches mean maintenance service
P54.32-5677-00
Multifunction display with maintenance interval display
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Page 16
Maintenance
Complete vehicle
15
Introduction of the smart fortwo, Model Series 451
Service flap
The smart fortwo is equipped with a detachable
service flap which allows convenient access to all
maintenance points in the front section. Customerrelevant maintenance items can be performed by the
customer accordingly.
To remove the service flap, levers located in the air
grille on each side must be operated to unlock the
service flap. The service flap can then be removed
and suspended by two brackets on the front of the
vehicle. A check strap prevents the service flap from
falling down.
Maintenance points at front end
The most important maintenance points at the front of
the car are:
• Brake fluid reservoir
• Windshield washer fluid reservoir
• Coolant expansion reservoir
• Lamp units for bulb replacement
P00.20-2629-00
Maintenance points at front end
1 Brake fluid reservoir
2 Windshield washer fluid reservoir
3 Coolant expansion reservoir
4 Lamp unit for bulb replacement
5 Service flap
6 Check strap
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Page 17
Maintenance
16
Complete vehicle
Introduction of the smart fortwo, Model Series 451
Maintenance points in engine compartment
The maintenance points in the engine compartment
can be accessed once the engine compartment cover
in the luggage compartment floor has been removed.
The most important maintenance points in the engine
compartment are:
• Oil filler neck
• Oil dipstick
• Air filter housing
• Spark plugs
P00.20-2630-00
Maintenance points in engine compartment
7 Oil filler neck
8 Oil dipstick
9 Air filter housing
10 Ignition coils (spark plugs)
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Page 18
Safety concept
Complete vehicle
17
Introduction of the smart fortwo, Model Series 451
In the smart fortwo, high levels of active safety are
provided by both tried-and-tested and newly developed systems and components.
Active safety
Active safety includes measures and equipment that
help to prevent detected dangers from occurring in
the first place, or that warn the driver of dangers in
advance, or that assist him in critical driving situations:
A distinction is drawn between the following safety
aspects:
• Driving safety
• Stress-reducing safety
• Perceptual safety
• Operating safety
The components responsible for maintaining driving
safety include:
• Electromechanical power steering (SA)
• 5-speed automated manual transmission
• Vehicle dynamics systems:
ABS (antilock brake system)
ASR (acceleration skid control)
ESP (electronic stability program)
High levels of stress-reducing safety are due to:
• Comfortable seats with integral head restraints
• Temperature-regulated air conditioning
High levels of perceptual safety are assured by
the following components:
• Auto on/off headlamps (SA)
• Center high-mounted brake lamp in the roof
spoiler
Operating safety is provided by:
• Ergonomically designed driver area
• Clearly arranged and easily reachable controls
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Page 19
Safety concept
18
Complete vehicle
Introduction of the smart fortwo, Model Series 451
Passive safety
The goal of a vehicle's passive safety is to minimize as
much as possible the effects of an accident on the
people involved. Some of the most important aspects
of this are the preservation of the survival space
(rigid passenger cell), high energy dissipation in the
event of an accident thanks to exploitable crumple
zones at the front and rear, and energy-absorbing
restraint systems in the interior.
The passive safety concept includes:
• tridion safety cell consisting of 50% high-strength
steel
• Crash management system (CMS) at the front and
rear, which absorbs energy at low vehicle speeds
and prevents expensive bodyshell damage
• Front end with no major assemblies, for effective
exploitation of the short overhang as a crumple
zone
• Inclusion of the wheels and axles/frame-type
integral support in the crumple zone and for force
application
• Front and rear structures with several impact
planes and large cross sections to transfer and
disperse the crash energy that is generated
• Long forward displacement area for the driver and
passenger with restraint systems adapted to
compensate for the "short" crumple zone
• Sturdy steel seat structures for effective
protection against shifting cargo and for specific
deformation in rear-end collisions
• Side doors made of solid steel frame profiles
including side impact protection
• Safe positioning of the fuel tank in the underfloor
area between the axles
• Deformable steering column to dissipate energy,
prevent intrusion and lengthen the forward
displacement distance in a frontal collision
• Full interior lining to reduce head injuries
The occupant restraint systems comprise:
• 2-stage driver airbag in steering wheel
• 2-stage top-mounted passenger airbag with
deployment opening on the top surface of the
instrument panel
• Head/thoraxbags in the backrests
• Three-point seat belts with emergency tensioning
retractors, belt force limiters and belt guides on
the backrests
• Seat belt reminders for driver and passenger
• Belt tension sensor on passenger side
• Passenger seat with Weight Sensing System (WSS)
with automatic passenger airbag deactivation for
the corresponding weight classes and airbag OFF
indicator lamp
• Full-length knee guard
• Two frontal acceleration sensors on front
crossmember
• Two satellite sensors on inner side wall in area of
left and right B-pillar
• Restraint systems control unit
P91.60-3663-00
1 Driver airbag
2 Passenger airbag
3 Head/thoraxbag
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Safety concept
Complete vehicle
19
Introduction of the smart fortwo, Model Series 451
Protective measures for pedestrians and cyclists
comprise:
• Single-piece front end module
• Main headlamps with predetermined fracture point
• Concealed and retracting windshield wiper shafts
• Energy-absorbing covering on the center piece in
front of the windshield
• Large, soft plastic surfaces at the front
The extended range of functions following an accident
includes:
• Automatic engine off feature
• Interruption of the fuel supply
• Unlocking of the doors
• Activation of the hazard warning system
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Page 21
On-board electrical system/power supply
20
Electrical system
Introduction of the smart fortwo, Model Series 451
General
The on-board electrical system ensures that the
power supply to all the electrical consumers and
components in the vehicle is appropriate for the
requirements and the situation.
The on-board electrical system consists of the
following main components:
• Starter
• Battery
• Alternator
• ME-SFI [ME] control unit
• Instrument cluster
Starter
The starter has an output of 0.95 kW and supplies the
torque necessary to start the engine. It takes the
necessary energy from the adequately charged
battery.
Battery
The battery (42 Ah) supplies the consumers when the
engine is off, the starter while the engine is being
started, and the on-board electrical system when the
alternator is unable to provide the required consumer
current.
The battery is located in the passenger footwell under
the carpeting.
There are three fuses located in the area of the
battery:
F36 Secondary air injection pump fuse
F58 Starter/alternator fuse
F91 SAM prefuse
P54.10-2890-00
G1 Battery
F36 Secondary air injection pump fuse
F58 Starter/alternator fuse
F91 SAM prefuse
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Page 22
On-board electrical system/power supply
Electrical system
21
Introduction of the smart fortwo, Model Series 451
Alternator
The alternator supplies the electrical consumers
while the engine is running and recharges the battery
so that a subsequent engine start is possible.
The alternator is equipped with an overvoltage
protection function that limits the on-board power
supply voltage in the event of a defect in the
governor. The alternator is monitored by the ME-SFI
[ME] control unit.
The alternator is pre-excited via a direct line. The
alternator load is reported back to the ME-SFI [ME]
control unit over a separate line and monitored.
Instrument cluster
The on-board power supply voltage is monitored by
the engine control. If the voltage is < 11.5 V for a
period of over 3 min, a signal is sent over CAN to the
instrument cluster and the alternator charge monitoring and warning lamp (A1e5) lights up.
P54.10-2891-00
G2 Alternator
P54.32-5684-00
A1 Instrument cluster
A1e5 Alternator charge monitoring and warning lamp
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Page 23
Complete networking
22
Electrical system
Introduction of the smart fortwo, Model Series 451
Overall network - location of components
P00.19-4338-00
Overall network - full equipment
A1 Instrument cluster
on the left side of the instrument panel
A15p4 Tachometer
(with code (V31) Cockpit clock and tachometer package)
in the center of the instrument panel
B24/15 Yaw rate, lateral and longitudinal accelera-
tion sensor
under the floor covering near the driver
seat
B32 ATA [EDW] microwave sensor
(with code (V01) Anti-theft alarm system
(FFO)) under the center console near the
handbrake lever
B38 Rain sensor/light sensor
(with code (V54) Rain/light sensor)
in the middle of the windshield near the inside rearview mirror
H3/2 Alarm siren with inclination sensor
(with code (V01) Anti-theft alarm system
(FFO)) on the right in front of the fuel tank
N2/7 Restraint systems control unit
in the center under the instrument panel
N3/10 ME-SFI [ME] control unit
behind the right side paneling in the rear
N10/10 SAM control unit
on the left under the instrument panel
N15/5 Electronic selector lever module control
unit
(Legend continued on the next page)
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Page 24
Complete networking
Electrical system
23
Introduction of the smart fortwo, Model Series 451
Overall network - CAN bus/LIN bus
P00.19-4339-00
Block diagram - Full equipment
N15/6 Automated manual transmission control unit
under the floor covering near the driver
seat
N23 Heater/AC operating unit
(with code (I01) Air conditioning Plus and
code (V30) Outside temperature sensor
(FFO))
in the center of the instrument panel
N25/5 Front HS [SIH] control unit
(with code (S17) Seat heaters (FFO))
in the center under the instrument panel
N47-5 ESP control unit
on ESP hydraulic unit
N49 Steering angle sensor in steering wheel
N57/2 Power window convenience feature control
unit
(with code (V43) Power windows)
on the left under the instrument panel
N68 Power steering control unit
(with code (V26) Power steering, EPS (FFO))
in interior compartment on left of firewall
N88 TPM [RDK] control unit
on left below instrument panel
N110 Weight Sensing System (WSS) control unit
on underside of passenger seat
X11/4 Data link connector
on the bottom of the instrument panel on the
driver side
CAN Controller Area Network bus
(data bus/CAN bus)
CAN-B Controller Area Network bus class B
(interior compartment)
LIN B Interior Local Interconnect Network 1
LIN C Interior Local Interconnect Network 2
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Page 25
Wiring harnesses
24
Electrical system
Introduction of the smart fortwo, Model Series 451
P54.18-4507-00
Wiring harness groups
The wiring harness is divided into the following groups:
1 Main wiring harness
2 Engine wiring harness
3 Transmission wiring harness
4 Battery wiring harness
Not illustrated:
- Door wiring harness
- Soft top wiring harness (in smart fortwo cabrio)
- Rear-end door wiring harness
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Page 26
Wiring harnesses
Electrical system
25
Introduction of the smart fortwo, Model Series 451
General
The wiring harness variants result from the basic
standard equipment, the special equipment items and
the national versions.
Repair capability
A basic wiring harness repair kit in a case is available
for repairing individual lines, wiring harnesses and
connectors without sealed plugs. All the above
repairs can be carried out using this kit.
It is also possible to expand the kit with a supplemental repair set to allow wiring harnesses with
sealed plugs to be repaired.
i Note
W000 589 13 99 00
Basic wiring harness repair kit.
Tools for repairing individual lines, wiring
harnesses and connectors in combination with the
wiring harness repair kit supplement for
passenger cars (W220 589 04 99 00).
W220 589 04 99 00
Wiring harness repair kit supplement for
passenger cars
Tools for repairing individual lines, wiring
harnesses and connectors in combination with the
basic wiring harness repair kit (W000 589 13 99
00).
P54.18-4140-00
Wiring harness repair kit
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Page 27
Diagnosis
26
Electrical system
Introduction of the smart fortwo, Model Series 451
General
The network architecture in model 451 allows external
access to individual control units in the CAN bus
system.
Data link connector
The CAN bus is accessed by means of a diagnostic
tester that is connected to the vehicle via the data link
connector. The data link connector is linked directly
to the CAN bus and can therefore access all the
control units that have diagnostic or programming
capability. The data link connector is located in the
vehicle interior on the underside of the instrument
panel on the driver side.
Diagnostic tester
By connecting the diagnostic tester, the vehicle with
all its equipment variants can be precisely identified.
This enables accurate fault evaluation and rectification and the analysis of vehicle-specific values and
parameters.
P54.22-2048-00
Location of data link connector (X11/4)
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Page 28
Diagnosis
Electrical system
27
Introduction of the smart fortwo, Model Series 451
Diagnosis capability
The following control units have diagnosis capability:
• Instrument cluster
• Restraint systems control unit
• WSS control unit
• ME-SFI [ME] control unit
• SAM control unit
• Automated manual transmission control unit
• Heater/AC operating unit
• ESP control unit
• Steering assist control unit
• TPM [RDK] control unit
• Electronic selector lever module control unit
Fault memory
Each of the control units listed above has a fault
memory that provides information about the associated systems. The stored faults are displayed by the
diagnostic tester and must be rectified. When all the
faults have been eliminates, the fault memory must be
erased and read out again. There should be no fault
entries left afterwards.
Maintenance intervals
The diagnostic tester is used to reset the maintenance interval in the instrument cluster following an
Oil Service Plus or a maintenance service.
Programming control units
The following control units can be programmed:
• ME-SFI [ME] control unit
• SAM control unit
• Automated manual transmission control unit
• ESP control unit
TAN generator
For the following applications a TAN (transaction
number) must be generated:
• Retrofitting the steering wheel gearshift (SAL)
• Replacing the ME-SFI [ME] control unit
• Replacing the SAM control unit
• Teach-in of transmitter keys (after loss or
detection of additional transmitter keys)
SCN (Software Calibration Number) coding
The following control units can be coded via the SCN
coding process:
• ME-SFI [ME] control unit
*)
• SAM control unit
• ESP control unit
• Automated manual transmission control unit
*)
• Restraint systems control unit
• Instrument cluster
*) The control unit is relevant to exhaust emissions,
i.e. the SCN is written in the control unit and can be
interrogated. For the other control units a virtual SCN
is generated during the coding process, but this is not
written to the control unit.
i Note
Up to six transmitter keys in total can be taught in
at the same time.
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Page 29
SAM control unit
28
Electrical system
Introduction of the smart fortwo, Model Series 451
Almost all of the fuses in model 451 are accommodated
on the SAM control unit. Slots 1-31 are located on the
front of the SAM control unit; slots 32-35 are located
on the rear.
The following fuses are not accommodated on the SAM
control unit:
• Secondary air injection pump fuse (F36)
• Starter/alternator fuse (F58)
• SAM prefuse (F91)
The SAM control unit is installed in the vehicle interior
on the left side near the A-pillar under the instrument
panel.
The SAM control unit is linked with the CAN in order to
exchange data. It communicates with the following
components:
• Instrument cluster
• ESP control unit
• Restraint systems control unit
• ME-SFI [ME] control unit
• Heater/AC operating unit
• Steering assist control unit
• TPM [RDK] control unit
• Weight Sensing System (WSS) control unit
• Yaw rate, lateral and longitudinal acceleration
sensor
• Steering angle sensor
• Data link connector
P54.21-2702-00
SAM control unit (front)
SN_Typ 451_us.book Seite 28 Freitag, 30. November 2007 1:56 13
Page 30
SAM control unit
Electrical system
29
Introduction of the smart fortwo, Model Series 451
The SAM control unit also communicates over:
• LIN B with the tachometer and the rain sensor/light
sensor
• LIN C with the ATA [EDW] microwave sensor and the
alarm siren with inclination sensor.
The fuse and relay box is integrated in the SAM
control unit.
The following relays are not accommodated on the SAM
control unit:
• Left turn signal/brake light relay (K52/11)
• Right turn signal/brake light relay (K52/12)
• Secondary air injection pump relay (K64)
• Soft top opening relay (K66/1) (only cabrio)
• Soft top closing relay (K66/2) (only cabrio)
P54.21-2703-00
SAM control unit (rear)
i Note
Up to six transmitter keys can be stored in the
SAM control unit.
SN_Typ 451_us.book Seite 29 Freitag, 30. November 2007 1:56 13
Page 31
Engine description
30
Engine M132
Introduction of the smart fortwo, Model Series 451
Engine M132
At market launch, the smart fortwo is available with a
3-cylinder gasoline engine with 61 in
3
(999 cm3)
displacement and 52 kW
P01.10-2942-00
3-cylinder gasoline engine (M132)
SN_Typ 451_us.book Seite 30 Freitag, 30. November 2007 1:56 13
Page 32
Performance graph
Engine M132
31
Introduction of the smart fortwo, Model Series 451
Power and torque graph
The red characteristic represents the power curve
(P) in relation to the engine speed (n).
The blue characteristic represents the torque curve
(M) in relation to the engine speed (n).
P01.00-2999-00
Power and torque graph M132
M Torque (lb-ft)
P Engine power (kW)
n Engine speed (rpm)
0
0 1000 2000 3000 4000 5000 6000 7000
20
40
60
80
100
120
140
160
180
M (lb-ft) P (kW)
n (1/min)
0
10
20
30
40
50
60
70
SN_Typ 451_us.book Seite 31 Freitag, 30. November 2007 1:56 13
Page 33
Engine data
32
Engine M132
Introduction of the smart fortwo, Model Series 451
* Fuel requirements:
Only unleaded premium fuel may be used. The octane
number (shown on the gasoline pump) should be at
least 91. This is an average value based on tests of the
octane number (RON) and motor octane number (MON)
(RON+MON/2). It is also known as the anti-knock
index.
M132
Engine model designation 132.910
Rated output kW
at rpm
52
5800
Rated torque lb-ft (Nm)
at rpm
68 (92)
4500
Compression ratio e 10.0:1
Engine configuration/no. of cylinders Inline/3
Camshaft configuration/number Overhead/2
Displacement in
3
(cm3)
61
(999)
Bore in
(mm)
2.83
(72)
Stroke in
(mm)
3.22
81.8
Cylinder angle ° 45
Fuel * Premium gasoline
unleaded
Emission regulations ULEV
SN_Typ 451_us.book Seite 32 Freitag, 30. November 2007 1:56 13
Page 34
Valve assembly
Engine M132
33
Introduction of the smart fortwo, Model Series 451
Valve assembly
The timing chain is driven by the crankshaft via the
crankshaft gear and thus drives the intake camshaft
via the camshaft adjuster and the exhaust camshaft
via the exhaust camshaft sprocket. The timing chain is
guided by a slide rail. A tensioning rail and chain
tensioner ensure that the chain is at the right tension
to prevent wear and noises.
The intake and exhaust camshafts control the gas
exchange in the engine via the intake and exhaust
valves. Variable camshaft adjustment allows for
greater torque at low engine speeds and better
response time in the idle and partial-load ranges. At
the same time, the camshaft adjustment helps to
achieve the stipulated exhaust emissions limits.
P05.00-2082-00
Valve assembly
1 Exhaust camshaft sprocket
2 Exhaust camshaft
3 Camshaft adjuster
4 Intake camshaft
5 Crankshaft gear
6 Crankshaft
7 Timing chain
8 Intake valve
9 Exhaust valve
10 Valve spring
11 Cup tappet
SN_Typ 451_us.book Seite 33 Freitag, 30. November 2007 1:56 13
Page 35
Valve timing
34
Engine M132
Introduction of the smart fortwo, Model Series 451
General
Engine M132 is equipped with mechanical cup tappets.
The mechanical stress on the cams and cup tappets
makes it necessary to check and adjust the valve clearance.
The cup tappets must be measured using a micrometer.
Find and insert the appropriate cup tappet by reference to its markings.
The valve clearance is adjusted by exchanging the cup
tappets. These are available in various thicknesses.
P05.30-2151-00
1 Cylinder head
2 Camshaft bearing cap
3 Intake camshaft
4 Exhaust camshaft
5 Cup tappet
6 Intake valve
7 Exhaust valve
8 Valve spring retainer
9 Valve locks
10 Valve spring
11 Valve stem seal
12 Valve seat
SN_Typ 451_us.book Seite 34 Freitag, 30. November 2007 1:56 13
Page 36
Gasoline injection and ignition system
Engine M132
35
Introduction of the smart fortwo, Model Series 451
Injection control
Engine M132 features an ME (motor electronics)
gasoline injection and ignition system. The central
control unit of this system is the ME-SFI [ME] control
unit. It is networked over CAN with the following
components:
• Instrument cluster
• SAM control unit
• Automated manual transmission control unit
• Heater/AC operating unit
• ESP control unit
• Steering assist control unit
• Data link connector
The ME-SFI [ME] control unit puts its information on
the CAN, making it accessible to all the other
networked components on the CAN. The information
from other components reaches the ME-SFI [ME]
control unit in the same way. For example, the signal
from the clutch motor, which is read directly by the
automated manual transmission control unit, reaches
the ME-SFI [ME] control unit in this way.
Direct input signals come from:
• Knock sensor
• Fuel tank pressure sensor
• Camshaft Hall sensor
• Coolant temperature sensor
• Accelerator pedal sensor
• O2 sensor downstream of TWC [KAT]
• O2 sensor upstream of TWC [KAT]
• Crankshaft position sensor
• Throttle valve actuator
• Oil pressure switch
Direct output signals go to:
• Fuel pump relay
• Fuel pump with fuel level sensor
• Secondary air injection pump relay
• Secondary air injection pump
• Secondary air injection pump switchover valve
• Throttle valve actuator
• Cylinder 1 ignition coil
• Cylinder 2 ignition coil
• Cylinder 3 ignition coil
• Outside air shutoff valve
• Adjustable camshaft timing solenoid
• Cylinder 1 fuel injection valve
• Cylinder 2 fuel injection valve
• Cylinder 3 fuel injection valve
• Fuel tank vent valve
There are also the following inputs on the ME-SFI [ME]
control unit:
• Circuit 15
• Circuit 30
• Circuit 31
Function
The engine is controlled according to load by the
performance map based on the signals arriving either
directly or over CAN. The actuators are actuated via
direct lines in accordance with the values computed
by the ME-SFI [ME] control unit. Information intended
for other components is put on the CAN.
The ME-SFI [ME] control unit has an integral fault
memory and can exchange information with STAR
DIAGNOSIS via a data link connector that is connected
to the CAN.
SN_Typ 451_us.book Seite 35 Freitag, 30. November 2007 1:56 13
Page 37
Gasoline injection and ignition system
36
Engine M132
Introduction of the smart fortwo, Model Series 451
P07.61-3578-00
Data flow chart of M132 injection system
SN_Typ 451_us.book Seite 36 Freitag, 30. November 2007 1:56 13
Page 38
Gasoline injection and ignition system
Engine M132
37
Introduction of the smart fortwo, Model Series 451
15/30/31 Circuit status
A1 Instrument cluster
A16 Knock sensor
B4/3 Fuel tank pressure sensor
B6/1 Camshaft Hall sensor
B11/4 Coolant temperature sensor
B28 Intake manifold pressure sensor
B37 Accelerator pedal sensor
G3/1 O2 sensor downstream of TWC [KAT]
G3/2 O2 sensor upstream of TWC [KAT]
K27 Fuel pump relay
K64 Secondary air injection pump relay
L5 Crankshaft position sensor
M3/3 Fuel pump with fuel level sensor
M16/6 Throttle valve actuator
M33 Secondary air injection pump
N3/10 ME-SFI [ME] control unit
N10/10 SAM control unit
N15/6 Automated manual transmission
control unit
N23 Heater/AC operating unit
N47-5 ESP control unit
N68 Steering assist control unit
S41/1 Oil pressure switch
T1/1 Cylinder 1 ignition coil
T1/2 Cylinder 2 ignition coil
T1/3 Cylinder 3 ignition coil
X11/4 Data link connector
Y32 Secondary air injection pump switchover
valve
Y49 Adjustable camshaft timing solenoid
Y50 Outside air shutoff valve
Y58 Tank vent valve
Y62/1 Cylinder 1 fuel injection valve
Y62/2 Cylinder 2 fuel injection valve
Y62/3 Cylinder 3 fuel injection valve
CAN Controller Area Network
(data bus/CAN bus)
SN_Typ 451_us.book Seite 37 Freitag, 30. November 2007 1:56 13
Page 39
Belt drive
38
Engine M132
Introduction of the smart fortwo, Model Series 451
Belt adjustment and description of stretch belt
Self-tensioning belt drive
The alternator and coolant pump are driven by a polyV belt with tensioning device.
The poly-V belt is tensioned via a new spring-loaded
tensioning device. To install and remove the poly-V
belt the tensioning device must be rotated clockwise
using a special tool to slacken the tension in the belt
drive. The tensioning device can then be locked in
place and the poly-V belt removed.
Stretch belt
The refrigerant compressor is driven by a stretch
belt.
The stretch belt does not need a tensioning device,
but it must be replaced after a specified mileage. It is
removed and installed with the aid of a special tool
that guides the stretch belt over the belt pulley of the
refrigerant compressor. The stretch belt can be
pulled on or off the belt pulley by cranking the engine
in its normal direction of rotation.
P13.20-2055-00
Belt drive
1 Alternator belt pulley
2 Poly-V belt
3 Coolant pump belt pulley
4 Refrigerant compressor belt pulley
5 Crankshaft pulley
6 Tensioning device
7 Tensioning device belt pulley
8 Stretch belt
SN_Typ 451_us.book Seite 38 Freitag, 30. November 2007 1:56 13
Page 40
Cooling system
Engine M132
39
Introduction of the smart fortwo, Model Series 451
Coolant circuit
In the small cooling circuit, the coolant is pumped
through the engine, the heater heat exchanger and
back to the engine via the expansion reservoir by the
coolant recirculation pump.
In the large coolant circuit, the coolant flows from the
thermostat straight to the radiator and on to the
coolant recirculation pump.
The switchover between the small and large coolant
circuit is performed by the thermostat depending on
the coolant temperature.
In the expansion reservoir the circuit is split again,
with one stream flowing direct to the coolant recirculation pump and the other passing through the radiator.
The coolant fan motor is switched on or off depending
on the engine temperature recorded by the coolant
temperature sensor and cools the coolant.
P20.00-2339-00
1 Radiator
2 Expansion reservoir
3 Coolant return line
4 Coolant feed line (large circuit)
5 Coolant pump
6 Coolant pump belt pulley
7 Thermostat
8 Coolant feed line (small circuit)
9 Heater heat exchanger
10 Coolant pipe
B11/4 Coolant temperature sensor
M4/2 Coolant fan motor
SN_Typ 451_us.book Seite 39 Freitag, 30. November 2007 1:56 13
Page 41
Cooling system
40
Engine M132
Introduction of the smart fortwo, Model Series 451
Bleeding cooling system
General
If some or all of the coolant has been drained, the
cooling system must be bled after refilling.
Fill
Unscrew the cooling system cap and fill the cooling
system up to the "MAX" mark in the expansion reservoir.
Bleeding
Unfasten the clamp, pull off the coolant hose and wait
until coolant emerges from the coolant hose and the
cylinder head. Then reconnect the coolant hose and
fasten it with the clamp.
Top up the expansion reservoir to the "MAX" mark
again and screw on the cooling system cap.
Warm up the engine until the thermostat opens. Switch
off the engine and check the coolant level in the
expansion reservoir.
P20.00-2340-00
1 Cooling system cap
2 Expansion reservoir
3 Coolant hose
4 Clamp
i Note
The cooling system must be filled and bled only
when the engine is cold.
SN_Typ 451_us.book Seite 40 Freitag, 30. November 2007 1:56 13
Page 42
Engine mount
Engine M132
41
Introduction of the smart fortwo, Model Series 451
Engine mount/torque support
The engine with transmission is mounted on two
mounts and a torque support. They were designed to
dampen inherent engine vibrations. They also considerably reduce the rocking of the drive assemblies
during load changes. The reduction in vibrations and
in the tendency to rock provides a higher level of
driving safety and ride comfort.
P22.10-2299-00
Engine mount, transmission mount and torque support
1 Frame-type integral support
2 Engine mount
3 Transmission mount
4 Torque support
SN_Typ 451_us.book Seite 41 Freitag, 30. November 2007 1:56 13
Page 43
Fuel supply
42
Fuel system
Introduction of the smart fortwo, Model Series 451
Fuel supply
A non-return fuel system is used for the fuel supply.
The fuel is pumped by a flow pump via the fuel filter in
the fuel tank into the fuel distributor rail according to
requirements.
Any surplus fuel is pumped via the fuel pressure
regulator straight into the buffer of the fuel pump.
The fuel pressure regulator is designed to ensure
that there is always a pressure of 46 psi (3.24 bar) at
the fuel distributor rail. The fuel tank fill level is
measured by a float-and-lever sensor.
Fuel tank
The fuel tank is located in front of the rear axle under
the seats. It is made of polyethylene and is formed
such that the available installation space is used to an
optimum. The capacity of the fuel tank is 8.72 gallons
(33 liters), including a 1.32 gallon (5 liter) reserve.
The intank fuel supply system consists of a fuel pump
with fuel level sensor, fuel pressure regulator and an
integrated fuel filter.
Evaporative emission control system (purging)
The evaporative emission control system prevents
fuel vapors escaping to the atmosphere. The fuel
vapors are stored in the activated charcoal filter and
then sent later to the engine for combustion.
Leak test
The leak test for the fuel evaporation control system
must detect leaks with a diameter as of 0.02 in (0.5
mm) and must take place in three stages (function
chain):
• Test for gross leaks (equal to or greater than 0.12
in (3 mm))
• Test for fine leaks (equal to or greater than 0.04 in
(1 mm))
• Test for very fine leaks (equal to or greater than
0.02 in (0.5 mm))
Test for gross leaks
The outside air shutoff valve is closed and the tank
vent valve is opened. Intake manifold vacuum present
in fuel tank. This vacuum is measured by the tank
pressure sensor.
If no vacuum is built up in the fuel tank (approx. -0.1
psi (-6 mbar) within approx. 12 seconds) there is a
major leak (e.g. tank cap open, hose line loose).
The test will be interrupted and the "gross leak" fault
will be registered.
If the ME-SFI [ME] control unit detects a system with
a gross leak, the fuel reserve warning lamp in the
instrument cluster flashes and the message "CHECK
FILLER CAP" appears in the multifunction display.
Test for fine leaks
The tank vent valve is closed at a vacuum of around -
0.1 psi (-6 mbar). The system is closed and thereby
airproof. The vacuum is then measured for approx. 30
seconds. The vacuum must not reduce more rapidly
than 0.004 to 0.007 psi/s (0.3 to 0.5 mbar/s) (depends
on fuel level). If the vacuum drops more rapidly, there
is a fine leak.
The test will be interrupted and the "fine leak" fault
will be registered.
SN_Typ 451_us.book Seite 42 Freitag, 30. November 2007 1:56 13
Page 44
Fuel supply
Fuel system
43
Introduction of the smart fortwo, Model Series 451
Check for very fine leaks
If no fine leak is recognized then purging is briefly
enabled and then the vacuum of about -0.1 psi (-6
mbar) is built up again. The vacuum must not reduce
more rapidly than 0.0014 to 0.002 psi/s (0.1 to 0.15
mbar/s) in the closed system (depends on fuel level).
If the vacuum drops more rapidly, the fault "very fine
leak" will be registered.
The reduction in vacuum depends on the fuel level in
the fuel tank and on outgassing of the fuel. The
outgassing of the fuel is measured just before the test
by the fuel tank pressure sensor and is allowed for
during fault determination.
The test for fine and very fine leaks is aborted if an
excessive lean correction of the lambda control takes
place during the build-up of the vacuum.
The function of the tank vent valve is checked at the
same time by the actuation. If the closed tank vent
valve jams, the fault "gross leak" is stored.
Test requirements
• Engine at idle
• Vehicle stationary
• Drive position "D" or "R" is engaged
• Off-period after engine start elapsed (approx. 16
minutes) or mixture adaptation performed
• Lambda control enabled
• Intake air temperature <113° F (<45 °C)
• Coolant temperature at engine start <212° F (<100
°C)
• Air injection not active
• Air pressure >1.12 psi (>780 hPa) (i.e. no tests
performed above approx. 2735 yd (2500 m)
altitude)
• Low loading of activated charcoal canister
• Fuel level in fuel tank between approx. ¼ and ¾
• No fault in outside air shutoff valve
• No fault in the fuel tank pressure sensor
• No fault in tank vent valve
• Battery voltage > 11 V
The outside air shutoff valve is reopened after the
tests.
SN_Typ 451_us.book Seite 43 Freitag, 30. November 2007 1:56 13
Page 45
Fuel supply
44
Fuel system
Introduction of the smart fortwo, Model Series 451
P47.-10-2433-00
Fuel system
1 Fuel tank
2 Activated charcoal filter
3 Vent line
4 Filler neck
5 Filler neck hose connection
6 Purge line
7 Fuel distributor rail
B4/3 Fuel tank pressure sensor
M3/3 Fuel pump with fuel level sensor
Y50 Outside air shutoff valve
Y58 Tank vent valve
SN_Typ 451_us.book Seite 44 Freitag, 30. November 2007 1:56 13
Page 46
Overview
Exhaust system
45
Introduction of the smart fortwo, Model Series 451
Design
The exhaust system is made of stainless steel and
consists of the following components:
• Exhaust manifold
• Catalytic converter
• Main muffler
Muffler system
When designing the muffler systems, it was important
both to minimize the exhaust back pressure and
achieve optimum acoustic tuning. The muffler system
is rigidly fixed to the vehicle body.
Exhaust aftertreatment
A control sensor and a diagnostic sensor are installed
for exhaust aftertreatment.
Aftertreatment of the exhaust gases is performed by
a catalytic converter with monolithic coating.
P49.00-2109-00
Exhaust system
1 Exhaust manifold
2 Catalytic converter
3 Main muffler
G3/1 O2 sensor downstream of TWC [KAT]
G3/2 O2 sensor upstream of TWC [KAT]
SN_Typ 451_us.book Seite 45 Freitag, 30. November 2007 1:56 13
Page 47
Secondary air injection
46
Exhaust system
Introduction of the smart fortwo, Model Series 451
Secondary air injection
Engine 132 is fitted with a secondary air injection
pump (electric air pump), which injects additional
fresh air in order to reduce exhaust gas emissions
after a cold start and to accelerate the warming of the
catalytic converter to its reaction temperature.
The necessary air is injected into the exhaust ports in
the cylinder head by the secondary air injection pump
via the combination valve. The secondary air injection
pump is actuated by the ME-SFI [ME] control unit via a
relay.
The secondary air injection pump switchover valve is
supplied with vacuum from the vacuum reservoir at
the intake manifold via a check valve.
When actuated, the secondary air injection pump
switchover valve releases vacuum to the combination
valve. This opens and the air injected by the
secondary air injection pump passes through to the
exhaust ports in the cylinder head.
The injected air reacts with the hot exhaust gases in
the outlet port. The carbon monoxide (CO) and hydrocarbon (HC) are oxidized. This "afterburning"
process increases the exhaust temperature and
reduces pollutants.
The duration of secondary air injection is dependent
on the coolant temperature.
The secondary air injection pump is only actuated at a
coolant temperature of 45 °F to 97 °F (7 °C to 36 °C)
and for a maximum duration of 33 seconds.
P14.30-2183-00
Secondary air injection
1 Cylinder head
2 Combination valve
3 Air hose
4 Vacuum hose
M33 Secondary air injection pump
Y32 Secondary air injection pump switchover
valve
SN_Typ 451_us.book Seite 46 Freitag, 30. November 2007 1:56 13
Page 48
Transmission description
Automated manual transmission
47
Introduction of the smart fortwo, Model Series 451
5-speed automated manual transmission (AMT 2)
The smart fortwo is fitted with the newly developed
2nd generation 5-speed automated manual transmission (AMT 2).
Advantages of the 5-speed automated manual transmission:
• Greater shift comfort
• Reduced fuel consumption
Features:
• 5-speed transmission
• Two-drum control
• Potentiometer-free position sensor system
• Mechanical park pawl
The driver can choose between two operating modes:
• Automatic mode (selector lever in position “D“)
• Manual mode (selector lever in position M “+/-“)
with operation via the selector lever or paddle
shifts on the steering wheel (SAL)
P26.10-2167-00
5-speed manual transmission (AMT 2)
SN_Typ 451_us.book Seite 47 Freitag, 30. November 2007 1:56 13
Page 49
Transmission description
48
Automated manual transmission
Introduction of the smart fortwo, Model Series 451
AMT 2 in model 451
Unit
Transmission model G 717.482
Number of forward/reverse gears 5/1
Max. transferable torque lb-ft
(Nm)
88
(120)
Clutch Single-plate dry clutch
Overall length (including 3 in (75 mm) for clutch) in
(mm)
14.3
(364)
Housing material Aluminum alloy
Weight (without oil charge) lb
(kg)
Approx. 74.9
(34)
Oil charge (permanent charge) US qt
(l)
2.4
(2.3)
Housing Two-piece with bell housing
SN_Typ 451_us.book Seite 48 Freitag, 30. November 2007 1:56 13
Page 50
Shift mechanism
Automated manual transmission
49
Introduction of the smart fortwo, Model Series 451
Shift mechanism
The central components of the shift mechanism are
two selector drums for moving the shift forks. Each
selector drum is driven by a separate electric motor
via two sintered spur gear sets. One selector drum
shifts the odd gears, while the other shifts the even
gears and reverse gear.
The position of the selector drum, and thus the
current shift position, is determined by two incremental sensors in each electric motor.
Both electric motors and the spur gears are located in
a common aluminum housing, the actuator unit, which
is mounted on the transmission.
The two selector drums are arranged to allow overlapping shift operations to minimize shift times. It is
possible to skip gears (e.g. double downshifts).
P26.60-2320-00
Design of shift mechanism
1 Shift fork for shift collar 5
2 Shift fork for reverse gear sliding gear
3 Shift fork for shift collar 1/3
4 Shift fork for shift collar 2/4
5 Main shaft
6 Selector drum 1/3, 5
7 Selector drum 2/4, R
8 Input shaft
M17/3 Transmission motor 1
M17/4 Transmission motor 2
SN_Typ 451_us.book Seite 49 Freitag, 30. November 2007 1:56 13
Page 51
Shift mechanism
50
Automated manual transmission
Introduction of the smart fortwo, Model Series 451
Function
The shift forks are displaced by the selector drums
parallel to the transmission shafts. They in turn slide
the shift collars on the input shaft or the main shaft
towards the respective idler gears.
The actuation of the shift forks is conducted by two
independent selector drums, each of which has a
groove. The sliding blocks for two shift forks run in
each groove.
Selector drum 1/3, 5:
• Sliding block of shift fork for shift collar 1/3
• Sliding block of shift fork for shift collar 5
Selector drum 2/4, R:
• Sliding block of shift fork for shift collar 2/4
• Sliding block of shift fork for sliding gear, reverse
gear
The positions of both sliding blocks in the same
groove are offset to each other by 120°. If a sliding
block displaces a shift fork from the center position,
the other sliding block is in the straight area of the
groove (in center position of respective shift fork).
Shift positions
Neutral (N) and reverse gear (R)
a Selector drum 1/3, 5
b Selector drum 2/4, R
c Selector drum adjustment (1 grid square =
40°)
d Sliding block deflection (1 grid square = 0.3 in
(7.5 mm))
Neutral position (N)
The sliding blocks in the grooves of the selector
drum are in the neutral position. No gear is
engaged.
Reverse gear (R)
The selector drum 2/4, R rotates through 120°
downwards. This displaces the upper sliding block
by 0.89 in (22.5 mm) to the left. The reverse gear
sliding gear engages in the outer teeth of shift
collar 1/3.
The sliding blocks in the selector drum 1/3, 5 are in
the neutral position.
P26.60-2356-00
SN_Typ 451_us.book Seite 50 Freitag, 30. November 2007 1:56 13
Page 52
Shift mechanism
Automated manual transmission
51
Introduction of the smart fortwo, Model Series 451
Shift positions
1st gear (1) and 2nd gear (2)
a Selector drum 1/3, 5
b Selector drum 2/4, R
c Selector drum adjustment (1 grid square =
40°)
d Sliding block deflection (1 grid square = 0.3 in
(7.5 mm))
1st gear (1)
The selector drum 1/3, 5 rotates through 40° downwards. This displaces the upper sliding block by 0.3
in (7.5 mm) to the left. The shift collar 1/3 is slid into
the idler gear of the first gear. The sliding blocks in
the selector drum 2/4, R are in the neutral position.
2nd gear (2)
For the change from 1st gear to 2nd gear, the two
selector drums rotate through 40° upwards. This in
turn displaces the lower sliding block in the
selector drum 2/4, R by 0.3 in (7.5 mm) to the left.
The shift collar 2/4 is slid into the idler gear of the
second gear. The sliding blocks in the selector
drum 1/3, 5 are in the neutral position.,
P26.60-2357-00
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Page 53
Shift mechanism
52
Automated manual transmission
Introduction of the smart fortwo, Model Series 451
Shift positions
3rd gear (3) and 4th gear (4)
a Selector drum 1/3, 5
b Selector drum 2/4, R
c Selector drum adjustment (1 grid square =
40°)
d Sliding block deflection (1 grid square = 0.3 in
(7.5 mm))
3rd gear (3)
For the change from 2nd gear to 3rd gear, the two
selector drums rotate through 40° upwards. The
upper sliding block in the selector drum 1/3, 5 is
displaced by 0.3 in (7.5 mm) to the right. It presses
the shift collar 1/3 into the idler gear of the third
gear. The other sliding blocks are in the neutral
position.
4th gear (4)
For the change from 3rd gear to 4th gear, the two
selector drums rotate through 40° upwards. The
lower sliding block in the selector drum 2/4, R is
displaced by 0.3 in (7.5 mm) to the right. It presses
the shift collar 2/4 into the idler gear of the fourth
gear. The other sliding blocks are in the neutral
position.
P26.60-2358-00
SN_Typ 451_us.book Seite 52 Freitag, 30. November 2007 1:56 13
Page 54
Shift mechanism
Automated manual transmission
53
Introduction of the smart fortwo, Model Series 451
Shift positions
5th gear (5)
a Selector drum 1/3, 5
b Selector drum 2/4, R
c Selector drum adjustment (1 grid square =
40°)
d Sliding block deflection (1 grid square = 0.3 in
(7.5 mm))
5th gear (5)
For the change from 4th gear to 5th gear, the
selector drum 1/3, 5 rotates through 40° upwards.
The lower sliding block in the selector drum 1/3, 5
is displaced by 0.3 in (7.5 mm) to the left. It presses
shift collar 5 into the idler gear of the fifth gear.
The selector drum 2/4, R is rotated through 40°
downwards. The sliding blocks in the selector drum
2/4, R are in the neutral position.
P26.60-2362-00
SN_Typ 451_us.book Seite 53 Freitag, 30. November 2007 1:56 13
Page 55
Synchronization
54
Automated manual transmission
Introduction of the smart fortwo, Model Series 451
Borg-Warner synchronization
All forward gears are equipped with a Borg-Warner
synchronization.
Reverse gear is not synchronized.
Function
Before the shift collar (3) positively connects the
sleeve carrier with the corresponding idler gear,
the tapered pairs of faces contact the clutch body
(1), synchronizer ring (2) and, where applicable, an
intermediate ring. The engine's gear is run at the
speed of the corresponding drive-side gear; only
then do the locking splines (4) release the
remaining travel of the shift collar. The shift collar
travel from neutral to complete engagement in the
relevant idler gear is approx. 0.3 in (7.7 mm).
P26.50-2173-00
1 Clutch body
2 Synchronizer ring
3 Shift collar
4 Locking splines
SN_Typ 451_us.book Seite 54 Freitag, 30. November 2007 1:56 13
Page 56
Transmission control
Automated manual transmission
55
Introduction of the smart fortwo, Model Series 451
Transmission rpm sensor (L2)
Location
The transmission rpm sensor is mounted to the
transmission housing.
Task
The rpm sensor determines the rotational speed of
the input shaft. The recorded speeds of the crankshaft and input shaft are used to monitor the clutch
operation. The speeds of the input shaft and the
drive wheels are used to determine the actual gear
engaged.
The diagram illustrates the oscilloscope picture of
an rpm sensor.
P26.19-2104-00
1 Input shaft
L2 Transmission rpm sensor
SN_Typ 451_us.book Seite 55 Freitag, 30. November 2007 1:56 13
Page 57
Transmission control
56
Automated manual transmission
Introduction of the smart fortwo, Model Series 451
Transmission motors 1 and 2 (M17/3 and M17/4)
Location
The transmission motors are located on the transmission housing.
Task
Depending on the shift request from the automated
manual transmission control unit (N15/6), the
transmission motors adjust the selector drums via a
two-stage spur gear transmission. Actuation is
pulse-width modulated by two output stages with
four electronic switches each. Upon reaching the
specified position the transmission motor is
braked. It can, if necessary, be actuated with
opposing voltage, if an overshoot beyond the specified position is to be prevented or reversed.
Actuation of the transmission motors is monitored
by the incremental sensors, which are located on
each motor shaft. These detect the rotation angle
and rotation direction of the respective transmission motor using the integrated Hall sensors.
The transmission motors are only actuated to
execute the shift operations. Once a target position
is reached, a pin engages in the locking groove of
the selector drum to maintain the selected gear.
P26.60-2321-00
1 Transmission motor 1 selector drum
2 Transmission motor 2 selector drum
M17/3 Transmission motor 1
M17/4 Transmission motor 2
SN_Typ 451_us.book Seite 56 Freitag, 30. November 2007 1:56 13
Page 58
Transmission control
Automated manual transmission
57
Introduction of the smart fortwo, Model Series 451
Automated manual transmission control unit (N15/6)
Location
The automated manual transmission control unit is
located in the passenger compartment under the
driver seat.
General
The transmission control converts the driver's
shift requests into corresponding control signals
to the clutch and the 5-speed automated manual
transmission.
This is done by relaying the shift signal about the
shift request at the electronic selector lever
module control unit over a direct line to the automated manual transmission control unit.
The automated manual transmission control unit
checks the plausibility of the shift request in
relation to the vehicle speed, the load (accelerator pedal position) and the engine speed.
If the plausibility check is passed, the automated
manual transmission control unit sends the signal
to initiate the selected shift operation to the two
actuator motors for the two selector drums and to
the clutch motor to open or close the clutch.
Task
The automated manual transmission control unit
controls the following functions depending on the
input information:
• Engaging first gear at vehicle standstill
• Gear change
• Compulsory upshift just before maximum
engine speed is reached
• Compulsory downshift when engine idle speed
is approached
• Downshift for kickdown
• Disengaging the gear after 1 s when a door is
opened without the service brake or
accelerator pedal being actuated
• Crawl function
• Clutch operation
• Monitoring of clutch load
P26.19-2145-00
N15/6 Automated manual transmission control unit
The automated manual transmission control unit
directly reads the signals from the following components:
• Transmission rpm sensor (L2)
• Transmission motor 1 (M17/3)
• Transmission motor 2 (M17/4)
• Clutch motor (M18)
• Electronic selector lever module control unit
(N15/5)
• Park pawl switch (S16/2)
SN_Typ 451_us.book Seite 57 Freitag, 30. November 2007 1:56 13
Page 59
Transmission control
58
Automated manual transmission
Introduction of the smart fortwo, Model Series 451
The following components are actuated directly by
the automated manual transmission control unit:
• Transmission motor 1 (M17/3)
• Transmission motor 2 (M17/4)
• Clutch motor (M18)
Communication via CAN takes place with the
following components:
• Instrument cluster (A1)
• ME-SFI [ME] control unit (N3/10)
• SAM control unit (N10/10)
• Electronic selector lever module control unit
(N15/5)
• ESP control unit (N47-5)
Electronic selector lever module control unit (N15/5)
Location
The electronic selector lever module control unit is
located in the center console.
Task
The electronic selector lever module control unit
records the shift requests of the driver.
The shift positions “N”, “R”, “+” and “-” are
detected by Hall sensors in the electronic selector
lever module control unit and are read and evaluated by the electronics in the electronic selector
lever module control unit. The signals corresponding to the shift lever positions are transferred to the automated manual transmission
control unit.
The release button on the selector lever must be
actuated in order to move the selector lever to the
following positions:
• From P to R, N or D
• From R to P
• From N to R or P
The transmitter key can only be removed in position
0 if the selector lever is in position P.
When the transmitter key is removed, the selector
lever is locked in position P.
P26.60-2375-00
1 Unlock button
N15/5 Electronic selector lever module control unit
P Park
R Reverse gear
N Neutral position
D Automatic mode
M Manual mode
+ Upshift
- Downshift
i Note
When reverse gear is requested, the backup light
is actuated directly by the electronic selector
lever module control unit.
SN_Typ 451_us.book Seite 58 Freitag, 30. November 2007 1:56 13
Page 60
Transmission control
Automated manual transmission
59
Introduction of the smart fortwo, Model Series 451
Manual mode
In manual mode (selector lever in position M), the
gears are shifted either using the selector lever or
using the paddle shifts on the steering wheel (SAL).
The gear which is currently selected is displayed on
the multifunction display in the instrument cluster.
The gear indicator may change to provide gearshift
recommendations (arrow up or down). The gearshift
recommendations are based on a driving style
which optimizes fuel consumption.
Automatic mode
In automatic mode (selector lever in position D), the
automated manual transmission control unit determines the gear changes. The selected gear range D
is displayed on the multifunction display in the
instrument cluster.
P54.32-5683-00
1 Gear range display (automatic mode)
2 Gear display (manual mode)
A1 Instrument cluster
A1p13 Multifunction display
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Page 61
Transmission control
60
Automated manual transmission
Introduction of the smart fortwo, Model Series 451
P26.19-2141-00
1 Circuit status
2 Shift request
3 Transmission speed
4 Clutch request
5 Clutch motor status
6 Gear change request
7 Transmission motor status
8 Engine speed
9 Backup light actuation
10 Vehicle speed
11 Shift program selection
12 Accelerator pedal position
13 Brake pedal status
14 Door status
15 Engaged gear
16 Gear indicator actuation
17 Park pawl status
A1 Instrument cluster
A45 Fanfare horns and airbag clock spring con-
tact
E3e3 Left backup light
E4e3 Right backup light
L2 Transmission rpm sensor
M17/3 Transmission motor 1
M17/4 Transmission motor 2
M18 Clutch motor
N3/10 ME-SFI [ME] control unit (gasoline engine)
N10/10 SAM control unit
N15/5 Electronic selector lever module
control unit
N15/6 Automated manual transmission
control unit
N47-5 ESP control unit
S16/2 Park pawl switch
S112s1 Steering wheel gear shifter PLUS (SAL)
S112s2 Steering wheel gear shifter MINUS (SAL)
CAN Controller Area Network
(data bus/CAN bus)
Data flow chart of transmission control
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Page 62
Park pawl
Automated manual transmission
61
Introduction of the smart fortwo, Model Series 451
Mechanical park pawl
In addition to the parking brake, the 5-speed automated manual transmission is equipped with a
mechanical park pawl to prevent the vehicle from
rolling away. The mechanical park pawl is operated
by the electronic selector lever module control unit
via a cable.
The status of the park pawl is reported to the automated manual transmission control unit via the park
pawl switch (S16/2).
P26.60-2377-00
1 Transmission
2 Cable
3 Park pawl
N15/5 Electronic selector lever module control unit
S16/2 Park pawl switch
SN_Typ 451_us.book Seite 61 Freitag, 30. November 2007 1:56 13
Page 63
Clutch
62
Automated manual transmission
Introduction of the smart fortwo, Model Series 451
Single-plate dry clutch
A single-plate dry clutch, consisting of clutch plate
and pressure plate, is installed on model 451.
An internal computer in the automated manual transmission control unit evaluates the clutch load. If a
threshold value is exceeded, the clutch starts to pulse
as an overload warning to the driver.
If the overloading continues, e.g. if the car is being
held with the clutch on a gradient, the clutch is closed
in order to provoke a stall.
P25.00-2010-00
Single-plate dry clutch
1 Pressure plate
2 Clutch plate
3 Flywheel with starter ring gear
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Page 64
Clutch
Automated manual transmission
63
Introduction of the smart fortwo, Model Series 451
Clutch motor
General
Model 451 is fitted with a 5-speed automated manual
transmission. This means that a single-plate dry
clutch is installed instead of the torque converter that
is usual with conventional automatic transmissions.
The single-plate dry clutch is actuated by the clutch
motor.
Function
When the automated manual transmission control unit
issues a request for a gear change, the clutch motor
is actuated at the same time. The electric motor integrated in the clutch motor operates the clutch via the
actuating plunger. The power flow is interrupted and
the shift operation can be performed.
P25.19-2010-00
4 Electric motor
5 Electric motor connector
6 Actuating plunger
M18 Clutch motor
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Page 65
Front axle
64
Chassis
Introduction of the smart fortwo, Model Series 451
Front axle
The front axle has a classic McPherson design.
The supporting ball joint is press-fitted with the
transverse control arm forming a single component
unit. If repairs are necessary, the supporting ball
joint must be replaced complete with the crossmember since a satisfactory press-fit cannot be
guaranteed in the repair shop.
The wheel bearing in the steering knuckle is not
available separately either because it is pressed into
the steering knuckle and can only be ordered as a
complete unit with the steering knuckle.
Adjustment capabilities
On the front axle it is only possible to adjust the toe;
the camber can only be corrected by utilizing the
"play" at the attachment points of the front axle.
P33.00-2086-00
Front axle - smart fortwo model 451
1 Front axle crossmember
2 Stabilizer bar
3 Transverse control arm with press-fitted support-
ing ball joint
4 Coil spring
5 Two-tube shock absorber
6 Wheel carrier, cast iron
with pressed-in wheel bearing
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Page 66
Rear axle
Chassis
65
Introduction of the smart fortwo, Model Series 451
Rear axle with suspension
The rear axle consists of:
• Axle tube
• Frame-type integral support
• Coil springs
• Bar link
• Single-tube shock absorbers
• Center bearing
The frame-type integral support supports the rear
wheel drive module. The coil springs are located at the
outsides and support the body against rolling movements.
The single-tube shock absorbers are fixed in place at
the top with pin bearings.
P35.00-2075-00
Rear axle - smart fortwo model 451
7 Axle tube
8 Frame-type integral support
9 Coil spring
10 Bar link
11 Single-tube shock absorber pin bearing
12 Single-tube shock absorber
13 Center bearing
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Page 67
Rear module
66
Chassis
Introduction of the smart fortwo, Model Series 451
Lowering the rear module
On model 451, the rear wheel drive module can be
lowered.
This shortens removal/installation time for various
major assemblies such as the refrigerant compressor,
starter, alternator etc., because all the attached
parts on the engine and the engine itself can be
reached very quickly and with relatively little effort.
This shortens repair times and reduces costs while
improving customer satisfaction at the same time.
P35.00-2085-00
Lowered rear drive module
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Page 68
Tire pressure monitor
Chassis
67
Introduction of the smart fortwo, Model Series 451
General
The tire pressure monitoring system (TPM [RDK])
monitors the air pressure in the individual tires and
improves active safety. A previously stored tire pressure is used as a comparative value. If a relevant loss
of pressure occurs, the tire pressure monitor
warning lamp in the instrument cluster warns the
driver. The tire pressure measuring range is p = 0 to
78 psi (p = 0 to 5.5 bar).
The TPM [RDK] system has the following subfunctions:
• Tire pressure sensing
• Warning display
• Manual restart
Function requirements
• Circuit 15 ON
• Tire pressure monitor (TPM [RDK]) system
functional
Tire pressure sensing
The TPM [RDK] control unit is permanently operational. Each time the CAN wakes up, the control unit
performs a re-initialization. While driving, the tire
pressure monitoring (TPM [RDK]) system continuously
monitors the tire pressure of all rotating wheels (with
circuit 15 OFF for a further t = 19 min). When the
vehicle is parked for t > 19 min, on-board wheel
detection and axle assignment must first be
completed via the TPM [RDK] wheel sensors. While
driving, the TPM [RDK] wheel sensors transmit data
telegrams every 60 seconds.
These data telegrams contain the following information:
• Tire pressure
• Tire air temperature
• Individual serial number
• Status information
(manufacturer, direction of rotation, operating
mode etc.)
In addition the TPM [RDK] control unit takes into
account the outside temperature and the vehicle
speed for the tire pressure determination. These data
are provided via CAN by the instrument cluster.
Warning indicator
A warning is issued when a relevant loss of pressure
has been detected in at least one of the tires. The
warning is issued in the instrument cluster via the tire
pressure monitor warning lamp, but the specific tire
where pressure loss has occurred is not specified.
Manual restart
The tire pressure to be monitored can be reset via the
TPM [RDK] switch on the cockpit switch panel. When
the TPM [RDK] switch is pressed, the current tire
pressure is stored in the memory of the TPM [RDK]
control unit and is then used as the reference pressure, as long as it is within the permissible limits.
The tire pressure monitor warning lamp in the instrument cluster flashes to indicate that a manual restart
has taken place.
i Note
A manual restart must be performed each time the
tire inflation pressure is changed and when a
wheel, wheel sensor or the TPM [RDK] control unit
is replaced.
If the nut on the valve element of a wheel sensor is
loosened, all components of the valve element
must be replaced.
See the Workshop Information System (WIS) for
further instructions and information.
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Page 69
Tire pressure monitor
68
Chassis
Introduction of the smart fortwo, Model Series 451
P40.15-2424-00
Location of TPM [RDK] components
A1 Instrument cluster
A1e66 Tire pressure monitor warning lamp
A69/1 Left front TPM [RDK] wheel sensor
A69/2 Right front TPM [RDK] wheel sensor
A69/3 Left rear TPM [RDK] wheel sensor
A69/4 Right rear TPM [RDK] wheel sensor
B14 Outside temperature display temperature
sensor
N10/10 SAM control unit
N88 TPM [RDK] control unit
S6/1 Cockpit switch group
S6/1s9 TPM [RDK] switch
SN_Typ 451_us.book Seite 68 Freitag, 30. November 2007 1:56 13
Page 70
Brakes
Chassis
69
Introduction of the smart fortwo, Model Series 451
Task
The task of the brake system is to brake the vehicle or
hold it at a standstill.
The system includes the service brake, which brakes
the vehicle while it is being driven, and the parking
brake, which secures the vehicle when it is at a standstill.
Components of the parking brake
• Hand brake lever with hand brake cables
• Parking brake mechanism integrated into rear
drum brake
Function of parking brake
When the handbrake lever is actuated, a relay lever is
actuated at the rear brake shoes of the left and right
drum brakes via the handbrake cables. This presses
the brake shoes of the drum brakes against the
insides of the brake drums to build up the required
brake force.
Components of the service brake
• Disk brakes with brake calipers on front axle
• Drum brakes with aluminum wheel brake cylinders
on rear axle
• Brake fluid reservoir
• Brake lines and brake hoses
• Brake pedal module
• ESP unit, consisting of ESP control unit and ESP
hydraulic unit
Function of service brake
The service brake is a hydraulic 2-circuit brake
system with TT (front/rear) split.
The force applied to the brake pedal is transferred to
the brake booster via a linkage. The brake booster
multiplies this forces and uses it to pressurize the
master brake cylinder. The brake pressure is built up
via the master brake cylinder.
The brake force is distributed to the disk brakes and
drum brakes by the ESP unit via the integrated
antilock brake system (ABS) and the electronic brake
force distribution (EBD) system.
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Page 71
Brakes
70
Chassis
Introduction of the smart fortwo, Model Series 451
P40.10-2711-00
Brake system
1 Brake pedal module
2 Brake disk
3 Brake caliper
4 Expansion reservoir
5 ESP unit
6 Hand brake cables
7 Drum brake (consisting of: anchor plate, wheel
brake cylinder, brake shoe, springs and brake
drum)
8 Hand brake lever
B24/15 Yaw rate, lateral and longitudinal accelera-
tion sensor
L6/1 Left front rpm sensor
L6/2 Right front rpm sensor
L6/3 Left rear rpm sensor
L6/4 Right rear rpm sensor
N47-5 ESP control unit
N49 Steering angle sensor
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Page 72
Brakes
Chassis
71
Introduction of the smart fortwo, Model Series 451
Brake pedal module
The brake pedal module is located on the underfloor
and consists of the following assemblies:
• Pedals
• Carrier
• Brake booster
• Master brake cylinder
Pedals
The pedals consist of:
• Pedal head
• Perforated boot
• Pedal assembly seal
• Housing
• Linkage rod
• Brake pedal module cover
• Seal for brake pedal module cover
• Brake light switch
P42.10-2712-00
Brake pedal module
9 Pedal head
10 Housing
11 Carrier
12 Brake booster
13 Master brake cylinder
14 Grommet
15 Brake pedal module cover
16 Linkage
17 Seal
18 Pedal assembly seal
19 Perforated boot
20 Bolt
S9/1 Brake light switch
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Page 73
Brakes
72
Chassis
Introduction of the smart fortwo, Model Series 451
Pedals
The seals and the boot on the pedals may not be
damaged otherwise moisture can penetrate into the
interior compartment.
To ensure that the pedals remain leaktight, the brake
pedal module cover must be replaced each time the
pedals are disassembled.
Brake light switch
The brake light switch in the pedal assembly is only
accessible after the brake pedal module cover has
been removed.
The brake light switch is actuated via the linkage in
the pedal assembly when the brake is actuated. The
signal from the brake light switch is read by the ESP
control unit.
The free travel of the brake light switch must be
correctly adjusted to ensure that the brake light
switch operates properly.
Brake lines
All brake lines may only be retightened twice at the
most when work is performed on the vehicle. If a
threaded connection on a brake line is loosened and
then retightened, this must be documented. The
respective threaded connection must be marked in
color with a suitable safety paint.
The following color codings are specified:
• First retightening: yellow marking
• Second retightening: red marking
If the respective threaded connection is loosened
again after being retightened for a second time, the
detached brake line must be replaced. This also
applies if it is not possible to trace how often the
threaded connection has previously been loosened.
Brake system bleeding
Whereas the brake fluid can be replaced by one
person, the hydraulic brake system can only be bled
by two people working together. When bleeding the
primary and secondary circuit, one person must build
up the pressure required by the brake fluid changer
by repeatedly actuating the brake pedal. The second
person is needed to:
• Actuate the ESP hydraulic unit via diagnosis at the
same time and perform the bleeding procedure
when bleeding the primary circuit
• Perform the bleeding procedure when bleeding the
secondary circuit
i Note
To ensure that the brake system is not damaged,
the filling pressure on the brake fluid changer
may be set to max. 2.8 psi (2 bar).
i Note
See the Workshop Information System (WIS) for the
exact procedure for repairing the brake system
and for the relevant safety information.
Basic adjustment of brake shoes
After brake shoes are replaced or removed/installed,
basic adjustment of the drum brake must be
performed. To do so, the brake shoes are measured
and adjusted using the slack adjuster.
Drum brake adjustment
Manual adjustment of the clearance between brake
shoe and brake drum is not permissible. Adjustment
may only be performed via the automatic slack
adjuster of the brake shoes to prevent grinding or
locking of the drum brake.
SN_Typ 451_us.book Seite 72 Freitag, 30. November 2007 1:56 13
Page 74
Brakes
Chassis
73
Introduction of the smart fortwo, Model Series 451
ESP system
The latest ESP system (version 8.1) is installed next to
the brake pedal module on the underfloor and
features the following functions:
• ABS
• ASR
• HBA
• EBD
• ESP
• EBR
• Start-off assist
Antilock brake system (ABS)
Prevents individual wheels from locking up by regulating the brake pressure at the relevant wheel
brakes. The vehicle remains steerable, enabling the
driver to take evasive action himself to avoid sudden
obstacles during emergency braking.
Acceleration skid control (ASR)
Prevents the drive wheels from spinning by intervening in the engine management and brake pressure
regulation. ASR provides good traction and improves
vehicle stability and steerability when moving off and
accelerating.
Hydraulic brake assist (HBA)
Regulates the pressure buildup in the brake system in
relation to the vehicle speed and the actuation speed
of the brake pedal. When emergency braking is
detected by means of characteristics defined beforehand, the ESP control unit actuates the return flow
pump that is integrated in the hydraulic unit. The
maximum brake pressure is built up.
Electronic brake force distribution (EBD)
Regulates the brake pressure at the rear wheels in
the partial braking range in order to improve the
stability of the vehicle and the braking effect.
Electronic stability program (ESP)
Minimizes oversteer or understeer by means of
specific intervention by the brake system at each
wheel on the front and rear axles. There may also be
intervention in the engine and transmission control
systems if necessary.
Engine braking regulation (EBR)
Reduces slip of the drive wheels in deceleration mode
and thereby improves directional stability and road
adhesion.
Start-off assist
Maintains the brake pressure for approx. 0.7 s after
the brake pedal is released to facilitate start-off on
uphill slopes.
Rpm sensors
The rpm sensors are active sensors, i.e. they must be
connected to a voltage source in order to operate.
They deliver a signal with an rpm-independent,
constant amplitude, and utilize the Hall effect to
detect the rpm signal.
Yaw rate, lateral and longitudinal acceleration sensor
The yaw rate, lateral and longitudinal acceleration
sensor is a combined sensor of micromechanical
design. It registers the yaw rate (yaw angle velocity)
of the vehicle about the vertical axis, the longitudinal
acceleration and the lateral acceleration.
i Note
In the event of an emergency stop in which the
vehicle is braked to a standstill from a speed in
excess of 43 mph (70 km/h), the SAM control unit
automatically activates the hazard warning
system. Deactivation of the hazard warning function occurs automatically when the vehicle speed
is detected to have risen above 6 mph (10 km/h) or
manually by actuation of the hazard warning
system switch.
SN_Typ 451_us.book Seite 73 Freitag, 30. November 2007 1:56 13
Page 75
Brakes
74
Chassis
Introduction of the smart fortwo, Model Series 451
P42.45-2662-00
Data flow chart of Electronic Stability Program ESP
1 ESP/ABS/ASR status
2 ESP/ABS/ASR display status
3 Wheel speed signal
4 Steering angle
5 Steering rate
6 Lateral and longitudinal acceleration
7 Yaw rate
8 Engine torque control
9 Transmission control intervention
10 Brake pedal status
11 Emergency stop reference speed
12 Driver door closed status
13 Handbrake status
14 Brake fluid status
A1 Instrument cluster
A1e41 ESP warning lamp
B24/15 Yaw rate, lateral and longitudinal accelera-
tion sensor
L6/1 Left front rpm sensor
L6/2 Right front rpm sensor
L6/3 Left rear rpm sensor
L6/4 Right rear rpm sensor
N3/10 ME-SFI [ME] control unit
N10/10 SAM control unit
N15/6 Automated manual transmission
control unit
N47-5 ESP control unit
N49 Steering angle sensor
S9/1 Brake light switch
S11 Brake fluid indicator switch
S12 Parking brake indicator switch
CAN Controller Area Network
(data bus/CAN bus)
SN_Typ 451_us.book Seite 74 Freitag, 30. November 2007 1:56 13
Page 76
Steering
Chassis
75
Introduction of the smart fortwo, Model Series 451
Rack-and-pinion steering
The smart fortwo features rack-and-pinion steering
as standard. The steering ratio is 22:1.
Electric power steering EPS (special equipment)
Electric Power Steering (EPS) is available as special
equipment. The steering ratio is 21:1.
The tasks of the EPS system are as follows:
• Power assistance with Servotronic
• Adaptation of the steering forces
• Active steering centering
General
Electric Power Steering (EPS) is a direct steering
system with integral speed-dependent power assistance and active steering centering. This ensures
that steering wheel forces remain low when the
vehicle is being maneuvered.
An electromechanical system offers the following
advantages compared to a conventional hydraulic
power steering system:
• Less weight and smaller installation space
• Greater degree of freedom to adjust the steering
assistance
• Reduced fuel consumption.
EPS operates without hydraulic components such as
pumps, reservoirs, coolers, lines and hydraulic fluid,
and is therefore a dry, environmentally compatible
system.
P46.10-2935-00
Electric power steering EPS
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Steering
76
Chassis
Introduction of the smart fortwo, Model Series 451
Design
The main components of the electric power steering
(EPS) system are the power steering motor, a DC
brush-type electric motor with maximum 35 Ampere
power consumption and the power steering control
unit.
The power steering control unit communicates via the
CAN data bus and is located in the vehicle interior on
the left of the firewall.
The rack-and-pinion mechanical components for the
electric power steering (EPS) are accommodated in a
steering housing made of diecast aluminum, to which
the power steering motor is also flange-mounted.
To provide steering assistance, the steering gear
pinion shaft transmits the rotational movement of the
steering gear input shaft to the teeth of the toothed
rack. The power steering motor transmits force for
steering assistance to the spur toothing of the hyperbolic gear via a worm shaft. The hyperbolic gear is
fixed to the pinion of the steering gear pinion shaft.
The power steering torque sensor is located in the
steering gear housing between the steering gear
input shaft and hyperbolic gear.
P46.10-2933-00
Components of the electric power steering (EPS)
1 Steering gear housing
2 Steering gear pinion shaft
3 Steering gear input shaft
4 Toothed rack
5 Worm shaft
6 Hyperbolic gear
B23 Power steering torque sensor
M19 Power steering motor
N68 Steering assist control unit
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Steering
Chassis
77
Introduction of the smart fortwo, Model Series 451
Function
Function requirement
Steering assistance is activated after engine start
and at a minimum engine speed of 500 rpm.
Steering power assistance
As the driver turns the steering wheel, a steering
torque is produced at the drag link which is registered by the power steering torque sensor and
forwarded to the power steering control unit.
The steering torque is used as an actuating variable
for the electric assistance force. It is derived from
the rotation of the torsion bar, which is located
between the steering gear input shaft and steering
gear pinion shaft on the same axis.
The power steering torque sensor is located around
the torsion bar. This determines the torque over a
range of +/- 8.1 lb-ft (11 Nm) and at a resolution of
0.037 lb-ft (0.05 Nm).
The power steering control unit uses the steering
torque measurement to determine the level of torque
that needs to be provided to supplement the steering
force.
Based on this information and depending on the
vehicle speed signal from the ESP control unit and the
engine speed signal from the ME-SFI [ME] control
unit, the power steering control unit determines the
current requirement of the power steering motor as
per the programmed characteristic field.
The power steering motor transmits the appropriate
supplementary steering torque to the face of the
hyperbolic gear via the worm shaft.
P46.10-2934-00
Steering torque of the electric power steering (EPS)
2 Steering gear pinion shaft
3 Steering gear input shaft
5 Worm shaft
6 Hyperbolic gear
7 Torsion bar
B23 Power steering torque sensor
M19 Power steering motor
N68 Steering assist control unit
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Steering
78
Chassis
Introduction of the smart fortwo, Model Series 451
Steering centering
This function returns the steering to the center position once the driver stops applying steering torque.
The power steering motor is actuated accordingly by
the power steering control unit.
"Active center feeling" function
When the steering wheel is registered in the center
position and there are no steering movements, the
power steering motor is energized by the steering
assist control unit so that a sufficient torque is
produced to hold the steering in the straightahead
position. This actuation conveys an improved steering
center feel to the driver. The system is continuously
calibrated and learns the center position automatically. The long-term calibration is performed via the
ESP wheel sensor system.
Limp-home function
The steering assist control unit constantly checks all
the input signals for plausibility. In the case of a faulty
component the steering, power assistance is shut
down and a fault is stored in the steering assist
control unit. The steering then continues to function
as a conventional rack-and-pinion steering.
i Note
If the electric steering suffers a function failure,
the electric steering indicator lamp in the instrument cluster lights up to indicate this.
i Note
The steering power assistance is at a maximum at
low speeds and when the vehicle is stationary and
decreases as the vehicle speed increases.
Once the vehicle stops and the engine is switched
off, the steering power assistance is deactivated
in stages after approx. 3 s.
To comply with EMC requirements, the energy line
from the power steering control unit to the power
steering motor is 85 % shielded against external influences.
The power steering control unit is a CAN bus
subscriber in the overall network. The vehicle speed,
the steering angle and other data are read in over
CAN.
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Steering
Chassis
79
Introduction of the smart fortwo, Model Series 451
P46.35-2034-00
Data flow chart of electric power steering EPS
1 Vehicle speed
2 Steering torque
3 Warning and fault message output
4 Power steering motor actuation
5 Steering angle, steering rate
6 Engine speed
A1 Instrument cluster
A1e18 Electric steering indicator lamp
B23 Power steering torque sensor
M19 Power steering motor
N3/10 ME-SFI [ME] control unit
N47-5 ESP control unit
N49 Steering angle sensor
N68 Steering assist control unit
CAN Controller Area Network
(data bus/CAN bus)
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Page 81
Steering
80
Chassis
Introduction of the smart fortwo, Model Series 451
Steering wheel
Two steering wheel variants are available for model
series 451.
Variants
• Leather two-spoke steering wheel of dia. 14.6 in
(370 mm) as standard equipment on the pure
• Three-spoke sport steering wheel with integrated
paddle shift of dia. 13.8 in (350 mm) as standard
equipment on the passion
Paddle shifts on steering wheel
In vehicles that are fitted with a three-spoke sport
steering wheel, the paddle shifts on each side of the
steering wheel can be used to shift up and down
through the gears. It is therefore possible to select a
gear on the steering wheel as well as via the gear
selector lever.
The left-hand paddle shift is used to downshift and the
right-hand paddle shift is for upshifts.
The gear which is currently engaged is displayed on
the multifunction display in the instrument cluster.
P46.10-2839-00
Two-spoke steering wheel
P46.10-2840-00
Three-spoke sport steering wheel with paddle shifts
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Steering
Chassis
81
Introduction of the smart fortwo, Model Series 451
Steering wheel removal and installation
The following components of the steering wheel are
replaceable:
• Contact unit with steering angle sensor
• Airbag module
• Paddle shifts (three-spoke sport steering wheel
only)
The steering wheel must be detached first before
replacing or removing/installing any of the above
components.
Care must be taken to ensure that the front wheels are
in the straightahead position, the battery is disconnected and the handbrake is applied before the
steering wheel is removed.
The exact procedure for removal/installation of the
steering wheel and its components is described in the
Workshop Information System (WIS).
i Note
All control units must be de-energized before the
steering wheel is removed. For this reason, at
least 15 minutes must elapse after the battery is
disconnected before it is removed.
i Note
Care must be taken to ensure that the turn signal
is not set when removing/installing the steering
wheel otherwise the trigger tab may be damaged.
P46.10-2841-00
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Page 83
Interior
82
Body
Introduction of the smart fortwo, Model Series 451
Interior design
The interior compartment has a classic look while still
displaying modern, typical smart features. This wellbalanced overall concept helps the smart fortwo
create an exclusive overall impression with high
perceived quality.
This is helped by the lines of the instrument panel, the
door linings and the seats shaped to match. The
harmonized color scheme of the interior also gives a
positive impression in combination with the passenger
compartment as a whole.
P68.00-5039-00
Shown on the smart coupé pure
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Interior
Body
83
Introduction of the smart fortwo, Model Series 451
Instrument panel
For the design of the instrument panel, particular
emphasis was placed on the following criteria:
• Ergonomics
• Clear layout
• Passenger safety
The instrument panel is designed with straight lines
and equipped with airbags and a full length knee
bolster to improve passenger protection.
Two additional instruments (tachometer and clock)
are available as special equipment (SA) and are positioned above the center console. The air vents on the
instrument panel have a cylindrical shape.
P68.10-3852-00
Shown on the smart coupé passion
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Interior
84
Body
Introduction of the smart fortwo, Model Series 451
Instrument cluster
In the center of the instrument cluster is the speedometer scale with the multifunction display underneath.
On each side is a strip with indicators and warning
displays, as well as the control buttons for the multifunction display.
The task of the instrument cluster is to provide the
driver with information about the various operating
states and to provide acoustic or visual warnings in
the event of critical operating conditions. It is the
display unit for the vehicle speed and for other
systems. In addition, the instrument cluster computes
the maintenance intervals and shows them in the
multifunction display.
The instrument cluster is a device on the data
bus/CAN bus in the overall network. Most of the
signals are transmitted or received over CAN. The
following signals are supplied to the instrument
cluster over direct lines:
• Signal from outside temperature indicator
temperature sensor
• Signal from "Fanfare horns and airbag clock spring
contact“ (only on variant with SAL).
The vehicle speed is displayed by an electronic
speedometer that is driven by a stepper motor. The
ESP control unit reads the information for the speed
display from the wheel speed sensors in the form of
signals, and forwards it over CAN to the instrument
cluster. The instrument cluster processes the
incoming signals and uses them to calculate the
vehicle speed and distance traveled.
Multifunction display
The task of the multifunction display is to provide the
driver with information about variable changes in the
vehicle, the ambient conditions and the road.
The variable displays include:
• Outside temperature
• Main odometer
• Trip odometer
• Gear indicator (in manual mode)
• Automatic transmission indicator (in automatic
mode)
• Fuel reserve indicator (US gal)
• Maintenance interval display with symbol
• Fuel level and reserve indicator
• Clock
P54.32-5677-00
Multifunction display
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Interior
Body
85
Introduction of the smart fortwo, Model Series 451
P54.30-9683-00
Instrument cluster
1 Left button, select multiple display / set
clock
2 Right button, instrument illumination / set
clock
A1 Instrument cluster
A1e1 Left turn signal indicator lamp
A1e2 Right turn signal indicator lamp
A1e3 High beam indicator lamp
A1e5 Alternator charge monitoring and warning
lamp
A1e7 Brake fluid and parking brake warning lamp
A1e9 Seat belt warning lamp
A1e15 Airbag indicator and warning lamp
A1e17 ABS indicator lamp
A1e18 Electric steering indicator lamp
A1e26 CHECK ENGINE indicator lamp
A1e30 Oil pressure warning lamp
A1e41 ESP warning lamp
A1e54 Coolant temperature warning lamp
A1e66 Tire pressure monitor warning lamp
A1e67 Low beam indicator lamp
A1p8 Electronic speedometer
A1p13 Multifunction display
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Page 87
Doors/flaps
86
Body
Introduction of the smart fortwo, Model Series 451
Side doors
The doors of the new smart fortwo follow the typical
smart brand construction principle with a metal
carrier part and the plastic CBS door paneling. The
doors of the smart coupé and the smart cabrio are
identical.
The triangular windows located above each door
handle are stationary windows held in place by bolts.
Crash requirements
The door support structure in model 451 is made of
steel. In addition, panels and sections of highstrength steel are used at strategically important
points. This is the case, for example, with the diagonal
struts and the side window slot frames.
In combination with the cockpit crossmember, this
makes the passenger compartment highly resistant to
side impacts in this section of the vehicle.
P72.00-2185-00
Door structure
1 Door carrier module
2 Diagonal strut
3 Side window slot frame
4 Cockpit crossmember
Emergency opening
Normally, the smart fortwo is opened from outside via
the standard-equipment central locking system using
the transmitter key.
If the battery in the transmitter key cannot supply
enough power, a lock cylinder installed behind a small
cover under the handle of the left door can be used to
open the driver door manually in an emergency.
P80.20-3225-00
1 Lock cylinder for emergency opening
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Doors/flaps
Body
87
Introduction of the smart fortwo, Model Series 451
P72.10-3403-00
Design of driver door with power window and electric outside mirror
1 Door carrier module
2 Window lifter mechanism
3 Diagonal strut
4 Top door hinge assembly
5 Bottom door hinge assembly
6 Inner door lining
7 CBS door paneling
8 Curved handle
9 Side window
10 Triangular window
H4/9 Left front speaker
M10/3 Left power window motor
M14/6 Left door CL [ZV] motor
M14/6s1 Left door CL [ZV] microswitch
M21/1 Left electrically adjustable and heated out-
side mirror
S21/1 Left power window switch
S21/2 Right power window switch
S50 Outside mirror adjustment switch
S87/7 Left door rotary tumbler microswitch
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Page 89
Doors/flaps
88
Body
Introduction of the smart fortwo, Model Series 451
Rear-end door
P72.20-2599-00
Design of rear-end door shown on the smart fortwo coupé
1 Upper rear-end door
2 Upper rear-end door paneling
3 Rear spoiler
4 Upper rear-end door hinges
5 Gas-operated strut
6 Rear window
7 CBS rear-end door paneling
8 Lower rear-end door
9 Right door lock of lower rear-end door
10 Left door lock of lower rear-end door
11 Door lock of upper rear-end door
12 Door panel lining
13 Lower rear-end door hinges
14 Seal
E21 Center high-mounted brake lamp
M6/4 Rear-end door wiper motor
S88/9 Rear-end door handle switch
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Doors/flaps
Body
89
Introduction of the smart fortwo, Model Series 451
Emergency unlocking of rear-end door
The rear-end door in the smart fortwo can be unlocked from the inside in an emergency, if the trunk lid central
locking motor for operating the rotary tumbler is defective or de-energized.
Emergency unlocking in smart fortwo coupé
To do this, a small tab at the side of the trunk lid lock
paneling must be carefully bent over or broken off to
produce a small hole.
A shop-made wire must then be inserted through the
small hole so that enough downward pressure is
exerted on the relay lever in the door lock to unlock
the rear-end door at the top.
A description of the procedure for manufacturing the
emergency release wire in the workshop is given in
the Workshop Information System (WIS).
Emergency unlocking in smart fortwo cabrio
In order to open the two door locks in the cabrio, a
hole must be accurately marked on the inside of the
rear-end door on each side. Then a hole of 0.2 in (5
mm) diameter is drilled through the paneling on each
side of the rear-end door..
A suitable screwdriver is inserted into each hole and
the rear-end door is unlocked by moving the screwdriver handles simultaneously in the directions of the
arrows.
The exact dimensions for the holes and a detailed
description of the procedure can be found in the
Workshop Information System (WIS).
P72.20-2583-00
A Actuation direction
1 Tab/paneling hole on trunk lid lock
2 Emergency release wire
P72.20-2582-00
B Actuation direction
3 Hole (0.2 in (5 mm))
4 Screwdriver
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Page 91
Roof systems
90
Body
Introduction of the smart fortwo, Model Series 451
Variants of roof system
Two roof variants are available for the model series
451 coupé. A fully electric Tritop fabric soft top is
installed in the cabrio.
smart fortwo coupé
• Full roof made of glass fiber reinforced
polyurethane (PU)
• Panoramic sunroof made of polycarbonate (PC)
smart fortwo cabrio
• Fully electric Tritop fabric soft top
P65.00-2119-00
Vehicle with PU roof
P77.21-2226-00
Vehicle with panoramic sunroof
P77.00-2338-00
Vehicle with fully electric Tritop fabric soft top
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Roof systems
Body
91
Introduction of the smart fortwo, Model Series 451
Hard roofs on smart fortwo coupé
Full roof
In the standard equipment pure version the smart
fortwo coupé is supplied with the polyurethane (PU)
full roof. The PU roof is only available in pitted matt
black.
The PU full roof sits on the body and is bonded to the
bodyshell structure.
Panoramic sunroof
A polycarbonate (PC) panoramic sunroof with steplessly variable roller sun blind is available for some
equipment variants.
The roof module is bonded to the tridion safety cell.
The latest in plastics technology makes it possible to
use breakproof material extensively in the vehicle.
The material is covered with a scratch-resistant
coating and the light transmission of the tint is
approx. 13 %. The material also provides 100 %
protection against UV light.
The steplessly adjustable inside roller blind can be
used to block out the sun. The roller sun blind is made
of a polyester fabric and covers the entire transparent area of the panoramic sunroof. The roof and
roller blind can be replaced separately.
The panoramic sunroof is manufactured by a twocomponent injection molding process in which the
second component material serves to blacken the
edges.
P77.21-2225-00
Panoramic sunroof with roller sun blind
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Roof systems
92
Body
Introduction of the smart fortwo, Model Series 451
Tritop fabric soft top
The Tritop fabric soft top of the smart fortwo cabrio
is the only one in the world that can be opened and
closed while driving up to the maximum speed. The
name TRITOP comes from the three main components
of the soft top:
• Folding top open
• Rear soft top stowed
• Side supports removed
The soft top control system is fully electronic and
features the following functions:
• Opening the folding top
• Closing the folding top
• Lowering the rear soft top
• Raising the rear soft top
P77.30-2390-00
Components of Tritop textile soft top
1 Folding top
2 Rear soft top
3 Left and right side supports
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Roof systems
Body
93
Introduction of the smart fortwo, Model Series 451
Soft top operation
The folding top and rear soft top are opened and
closed using the power soft top switch on the electronic selector lever module control unit.
The folding top can also be opened remotely and automatically by means of a button on the transmitter key.
To operate the soft top via the power soft top switch
the vehicle's ignition must be switched on.
A short press of the power soft top switch in the
"Open" direction causes the folding top to open all the
way to its end position.
The folding top must always be fully opened before the
rear soft top can be opened. If the power soft top
switch is then pressed again and held in the "Open"
direction, the rear soft top is folded away for as long
as the switch is actuated. As soon as the rear soft top
has been stowed in its end position, its motors cut out
and the switch can be released.
To close the soft top, the power soft top switch is
pressed and held in the "Close" direction until the
rear soft top has reached its upper end position and
the motors of the rear soft top cut out; the switch can
then be released.
If the power soft top switch is pressed and held again,
the folding top closes until it reaches its own end
position and the motor cuts out; then the switch can be
released again.
The rear soft top and folding top lock automatically as
soon as they reach their end positions.
i Note
For safety reasons, it is not possible to close the
folding top automatically. There would be a risk of
injury during the closing process because limbs of
vehicle occupants could become trapped between
the roof frame and folding top in the area of the
windshield.
P80.35-2333-00
3 Folding top automatic open button
A Transmitter key
P77.00-2332-00
S84 Power soft top switch
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Roof systems
94
Body
Introduction of the smart fortwo, Model Series 451
Targa roof position
In the targa roof position, the folding top is fully
opened, the side supports are removed and the rear
soft top is closed.
The targa roof position is important with regard to the
operation of the folding top because the side
supports must be inserted before the folding top can
be closed. The side supports are detected by a
mechanical catch in the roof cassette lock.
Soft top control
The central controller unit of the soft top is the SAM
control unit.
The SAM control unit reads in the actuation request
from the power soft top switch and actuates the
appropriate motors depending on the position and
status of the soft top.
The soft top is powered by a total of three motors. A
central motor in the roof cassette is responsible for
opening and closing the folding top. The folding and
raising of the rear soft top is carried out by two
motors in the left and right main bearings of the soft
top.
The soft top also incorporates the center highmounted brake lamp and a glass rear window with an
integral rear window heater, which is also activated by
the SAM control unit.
Function sequence of soft top actuation
Function requirements:
• Switch circuit 15 ON
Pressing the power soft top switch sends a direct
signal to open or close to the SAM control unit. The
SAM control unit reads in the signal, checks whether
the function requirements are satisfied and determines the status of the soft top via the microswitches
installed on the soft top. If all the preconditions are
met, the SAM control unit actuates the appropriate
motor(s) for the desired operation.
P77.00-2340-00
Targa roof position
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Roof systems
Body
95
Introduction of the smart fortwo, Model Series 451
P77.39-2210-00
Data flow chart of soft top control
1 Circuit 15 ON
2 Request to open folding top
3 Request to open rear soft top
4 Request to close rear soft top
5 Request to close folding top
6 Status of soft top
7 Status of roof cassette latch
8 Status of rear soft top
9 Vehicle speed
A1 Instrument cluster
K66/1 Open soft top relay
K66/2 Close soft top relay
M12/6 Electric soft top motor
M12/7 Left soft top drive
M12/8 Right soft top drive
N10/10 SAM control unit
S2/1 Ignition/starter switch
S84 Power soft top switch
S84/37 Folding top microswitch
S84/38 Left roof cassette microswitch
S84/39 Right rear soft top microswitch
S84/40 Right roof cassette microswitch
S84/41 Left rear soft top microswitch
A Transmitter key
CAN Controller Area Network
(data bus/CAN bus)
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Page 97
Central locking
96
Body
Introduction of the smart fortwo, Model Series 451
Central locking (CL [ZV])
The central locking in the smart fortwo includes the
locking and unlocking of both doors and the fuel filler
flap, and the opening of the rear-end door in the
smart coupé or the opening of the soft top on the
smart cabrio. A distinction is drawn between manual
and automatic functions.
Manual functions:
• Remote control with the transmitter key
• Door opening from the inside
• Operation via the interior CL [ZV] locking and
unlocking switches in the cockpit switch group
• Manual unlocking with the transmitter key at the
driver-side door lock
Automatic functions:
• Speed-dependent locking
• Emergency opening after crash detection
• Relocking
Unlocking or locking via the transmitter key
When the Unlock or Lock button on the transmitter key
is pressed, it sends a radio signal to the SAM control
unit. The SAM control unit checks the access authorization of the transmitter key. If the access authorization is valid, it actuates the following motors directly
to unlock or lock the vehicle:
• Right door CL [ZV] motor
• Left door CL [ZV] motor
• Fuel filler flap CL [ZV] motor
When the vehicle is globally unlocked, the rear-end
door handle switch is enabled; and when the vehicle is
locked, it is disabled.
If the rear-end door handle switch is actuated when
the central locking has been globally unlocked, the
SAM control unit directly actuates the trunk lid CL
[ZV] motor to unlock the rotary tumbler.
Selective unlocking
If the Unlock button on the transmitter key is pressed
once, only the driver door and fuel filler flap are
unlocked. The anti-theft alarm system is deactivated
and all turn signal indicators flash once.
Global unlocking
If the Unlock button on the transmitter key is pressed
again, the passenger door is unlocked and the rearend door handle switch is enabled. The turn signal
indicators flash again once.
Door opening from the inside
The vehicle doors can always be opened from the
inside with the door handle regardless of the status of
the central locking. In this case, only the respective
vehicle door and the fuel filler flap are unlocked.
P80.35-2332-00
A Transmitter key
1 Locking button
2 Unlocking button
3 Open folding top button (cabrio)
Open rear-end door button (coupé)
4 PANIC button
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Central locking
Body
97
Introduction of the smart fortwo, Model Series 451
PANIC alarm
Pressing the PANIC button for at least 1 s triggers an
acoustic alarm. The turn signal indicators also flash.
The alarm is deactivated when
• Circuit 15 is switched ON or
• The PANIC button is pressed
Unlocking and locking from the inside via the
switches in the cockpit switch group
When the side doors and the rear-end door are
closed, pressing the "Lock or unlock" switch in the
cockpit switch group causes a signal to be sent
straight to the SAM control unit. This actuates the
central locking motors. The vehicle doors and the fuel
filler flap are either locked or unlocked accordingly
and the rear-end door handle switch is either enabled
or disabled.
Special function:
If the vehicle cannot be locked using the transmitter
key due to a flat battery in the key, proceed as follows:
• Open driver door
• Switch circuit 15 ON
• Actuate inside CL [ZV] switch
• Within 5 s, switch circuit 15 OFF and remove
transmitter key
• Close driver door, vehicle is locked.
Manual unlocking of the driver door with the transmitter key at the door lock
When the door lock on the driver door is operated with
the transmitter key, the driver door and (if the onboard power supply voltage is sufficient) the fuel
filler flap are unlocked.
If the antitheft alarm system on the vehicle is armed,
an alarm is triggered.
Speed-dependent locking
The vehicle is automatically locked if circuit 15 is ON
and the vehicle speed exceeds 8 mph (14 km/h).
Speed-dependent locking can be activated or deactivated as required.
Relocking
This function relocks the vehicle automatically if none
of the doors is opened 60 s after unlocking.
Emergency opening after crash recognition
This functions unlocks the doors after an accident
that triggers a crash signal.
Remote rear-end door opening (smart fortwo coupé
only)
When the "Open rear-end door" button on the transmitter key is pressed, it sends a radio signal to the
SAM control unit. This checks the access authorization
of the transmitter key. If the access authorization is
valid, the SAM control unit actuates the trunk lid CL
[ZV] motor directly.
Remote folding top opening (smart fortwo cabrio
only)
When the "Open folding top" button on the transmitter
key is pressed, it sends a radio signal to the SAM
control unit. This checks the access authorization of
the transmitter key. If the access authorization is
valid, the SAM control unit actuates the electric soft
top motor directly.
i Note
The radio signal for unlocking the door is picked
up by an antenna integrated in the SAM control
unit. There is no external antenna for the central
locking.
SN_Typ 451_us.book Seite 97 Freitag, 30. November 2007 1:56 13
Page 99
Central locking
98
Body
Introduction of the smart fortwo, Model Series 451
1 Unlocking/locking request
2 Doors status
3 Rear-end door status
4 Unlocking/locking actuation
5 Rear-end door unlocking request
6 Visual feedback actuation
7 Rear-end door unlocking actuation
8 Unlocking via inside door opener request
9 Inside unlocking/locking request
10 Emergency opening request
11 Rear-end door opening request (coupé)
12 Open soft top actuation (cabrio)
13 Open soft top request (cabrio)
14 Vehicle speed
A1 Instrument cluster
E1e5 Left turn signal light
E2e5 Right turn signal light
E3e11 Left brake/turn signal light
E4e11 Right brake/turn signal light
E22/1 Left additional turn signal lamp
E22/2 Right additional turn signal lamp
M12/6 Electric soft top motor (cabrio)
M14/5 Right door CL [ZV] motor
M14/5s1 Right door CL [ZV] microswitch
M14/6 Left door CL [ZV] motor
M14/6s1 Left door CL [ZV] microswitch
M14/7 Rear-end door CL [ZV] motor
M14/10 Fuel filler flap CL [ZV] motor
N2/7 Restraint systems control unit
N10/10 SAM control unit
S6/1 Cockpit switch group
S6/1s1 Hazard warning flasher switch
S6/1s11 Inside unlock CL [ZV] switch
S6/1s12 Inside lock CL [ZV] switch
S15 Remote trunk opening switch
(coupé)
S17/8 Trunk lid rotary tumbler microswitch
(cabrio)
S88/9 Rear-end door handle switch
A Transmitter key
CAN Controller Area Network
(data bus/CAN bus)
P80.20-3177-00
SN_Typ 451_us.book Seite 98 Freitag, 30. November 2007 1:56 13
Page 100
Anti-theft alarm system (ATA [EDW])
Body
99
Introduction of the smart fortwo, Model Series 451
ATA [EDW] system
The anti-theft alarm system (ATA [EDW]) monitors all
relevant inputs for their non-actuated state. If a
change of status is detected at one of the monitored
inputs, an acoustic and visual alarm is issued.
The acoustic signals are output by the alarm signal
siren with inclination sensor. The visual signals are
output via the turn signal indicators. The SAM control
unit is the master control unit for the anti-theft alarm
system (ATA [EDW]).
When armed, the anti-theft alarm system (ATA [EDW])
monitors:
• The doors
• The rear-end door
• The alarm siren with inclination sensor
• The position change of the vehicle
• Movements in the interior compartment
Activation and deactivation
The anti-theft alarm system (ATA [EDW]) is activated
when the vehicle is locked with the transmitter key.
The anti-theft alarm system (ATA [EDW]) is deactivated by unlocking the vehicle with the transmitter
key or by inserting an authorized transmitter key in
the ignition lock and turning circuit 15 ON.
Alarm triggering
An alarm is triggered when the SAM control unit
receives a status change from the following components:
• ATA [EDW] microwave sensor
• Inclination sensor in alarm siren
• Trunk lid rotary tumbler microswitch
• Right door rotary tumbler microswitch
• Left door rotary tumbler microswitch
Alarm output
The alarm is output via the turn signal indicators and
the alarm siren with inclination sensor.
Interior protection/tow-away protection
The ATA [EDW] microwave sensor is activated approx.
30 s after the vehicle is locked. Interior protection
can be deactivated using the tow-away protection/interior protection switch.
The inclination sensor in the alarm siren with inclination sensor registers a positional change of the
vehicle. The inclination sensor, and thus the tow-away
protection, can be deactivated using the tow-away
protection/interior protection switch.
The interior protection or tow-away protection is
reactivated automatically the next time the vehicle is
locked.
SN_Typ 451_us.book Seite 99 Freitag, 30. November 2007 1:56 13
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