Service Training
Commercial
Vehicles
Self-study Programme 370
The Crafter
Electrical system
Design and function
Innovations in automotive engineering are also taking place in the commercial vehicle segment.
The Volkswagen Crafter is therefore fitted with extensive electrical equipment and with electrical and optical data bus systems.
In comparison with the predecessor model, these systems enable familiar electrical functions to be actuated in different ways and new functions to be implemented.
This self-study programme is intended to explain these functions and help you to understand their interconnections better.
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Important |
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Note |
The self-study programme shows the design and function of new developments.
The contents will not be updated.
For current testing, adjustment and repair instructions, refer to the relevant
service literature.
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Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Vehicle electrical system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Ignition lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Anti-theft system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
Dash panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
Convenience systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Tachograph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Special control units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78
Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Test yourself . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
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Introduction
Data bus systems
Data bus networking
The Volkswagen Crafter's control units are networked via the CAN data bus and the MOST data bus.
Networking enables data to be exchanged between the individual control units.
Instead of using conventional (discrete) cable connections, the data are transmitted via the data buses in digital form as an electrical signal or
as a light signal. This makes it possible to make data available to several control units.
The CAN data bus is sub-divided into three individual systems, the CAN drive data bus, the CAN convenience data bus and the CAN diagnostic data bus.
All three bus systems are connected to each other via the electronic ignition lock D9, and are therefore able to exchange information.
Diagnostic |
MOST data bus |
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interface |
interface |
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CAN drive |
MOST data bus |
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data bus |
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CAN |
Data bus |
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K-wire |
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convenience |
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data bus |
Serial data cable |
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Legend
D9 Electronic ignition lock
E16 Heater/heat output switch
J104 ABS control unit
J234 Airbag control unit
J285 Control unit in dash panel insert
J301 Air conditioning system control unit
J345 Trailer detector control unit
J364 Auxiliary heater control unit
J386 Driver door control unit
J412 Mobile telephone operating electronics control unit
J446 Parking aid control unit
J502 Tyre pressure monitor control unit
J503 Control unit with display for radio and navigation
J514 Electronic manual gearbox control unit
J519 Onboard supply control unit
J527 Steering column electronics control unit
J528 Roof electronics control unit
J604 Auxiliary air heater control unit
J621 Tachograph control unit
J623 Engine control unit
J764 Electronic steering column lock control unit
J819 Control unit for middle of dash panel
J820 Control unit for programmable special functions
RRadio
R41 CD changer
T16 16-pin connector (diagnostic connection)
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5
Introduction
Installation locations of the electrical components
Overview of installation locations
The vehicle electrical system has a decentralised structure; the fuse and relay installation locations are therefore in different locations throughout the vehicle.
Junction boxes 2 and 3 for bus systems,
on the right A pillar
Fuse holder (SA),
on right-hand side of battery, visible only following removal
Connector (T16, diagnostic connection), on the left A pillar
6
Fuse holder D (SD), beneath the driver's seat
Fuse holder B (SB), left A pillar
Fuse holder C (SC), on the left A pillar
Junction box 1 for bus systems, |
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beneath the front left dash panel |
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7
Introduction
Installation locations of the control units in the CAN drive data bus
Control units and installation locations
The adjacent illustration shows the control units which take part in CAN drive data bus data communication and their installation locations.
Data are transmitted at a speed of
500 kbit/s. Transmission is carried out via the CAN high cable and the CAN low cable. CAN high cables are green/white and the CAN low cables are green.
To ensure reliable data transmission, the CAN cables are twisted together.
The CAN drive data bus is not 1-wire-capable;
if a CAN cable fails, no data transmission is possible.
Steering column electronics control unit J527,
on the steering column
Electronic ignition lock D9,
on the right next to the steering wheel
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ABS control unit J104,
on the left in the engine compartment
Engine control unit J623,
on the left in the engine
compartment S370_004
9
Introduction
Installation locations of the control units in the CAN convenience data bus
Control units and installation locations
The adjacent illustration shows the control units which take part in CAN convenience data bus data communication and their installation locations.
Data are transmitted at a speed of
83.3 kbit/s. Transmission is carried out via the CAN high cable and the CAN low cable.
CAN high cables are brown/red and the CAN low cables are brown.
To ensure reliable data transmission, the CAN cables are twisted together.
The CAN convenience data bus is 1-wire-capable; if a CAN cable fails, data transmission remains possible.
Air conditioning system control unit J301, in centre of dash panel
Control unit for middle of dash panel J819, in centre of dash panel
Radio R/control unit with display for radio and navigation J503 *,
in centre of dash panel
*Acts as the interface for the MOST infotainment data bus
Electronic ignition lock D9,
on the right next to the steering wheel
10
Airbag control unit J234, beneath the centre console
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Trailer detector control |
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Auxiliary heater control unit J364, |
unit J345, |
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in moulded headlining near to the interior mirror |
beneath the front left seat |
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Roof electronics |
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control unit J528, |
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in moulded |
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headlining near to |
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the interior mirror |
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Control unit for programmable special functions J820, beneath the front left seat
Parking aid control unit J446, beneath the front left seat
Tyre pressure monitor control unit J502, beneath the front left seat
Driver door control unit J386, in the front left door
Onboard supply control unit J519, |
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on the left A pillar |
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Introduction
Installation locations of the control units in the MOST infotainment data bus
Control units and installation locations
Besides the familiar CAN data bus systems,
the Volkswagen Crafter is also equipped with an optical data bus system.
This data bus system has been named according to the "Media Oriented Systems Transport" (MOST) cooperation.
This co-operation has been established by various car manufacturers, their suppliers and software companies in order to implement a standardised system for fast data transmission.
The optical MOST data bus is used to exchange data between the radio/control unit with display for radio and navigation, the CD changer and the mobile telephone operating electronics control unit by means of light waves.
In comparison with radio waves, light waves have very short wavelengths, do not generate electromagnetic interference waves, are simultaneously insensitive to these and have
a significantly higher data transmission rate than electronic data bus systems.
On routing, the radius of the fibre optical cable must be at least 25 mm.
Mobile telephone operating electronics control unit J412, behind the glove box
Control unit with display unit for radio and navigation J503/radio R,
in centre of dash panel
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CD changer R41, centre of vehicle interior
S370_071
During diagnosis, please observe the Guided Fault Finding instructions.
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Vehicle electrical system
Batteries
Equipment
The Volkswagen Crafter can be optionally equipped with a dual-battery vehicle electrical system; in this case, a starter and a vehicle electrical supply battery are installed.
Starter battery
The vehicle electrical system's standard 12 V vehicle voltage is supplied by the maintenance-free starter battery. The starter battery is installed in the covered battery recess in front of the driver's seat (left-hand drive vehicle) or the front passenger's seat (right-hand drive vehicle).
A vent pipe emerges into the open air from the recess.
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Vehicle electrical system battery
To supply high-current, body-side consumers,
a second battery, located on the left of the engine compartment, is available in addition to the starter battery (left-hand drive vehicles only). This second battery is not intended as a starter battery.
By supplying the high-current consumers, it is instead intended to protect the starter battery from discharge, thereby maintaining the vehicle's ability to start.
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Functional diagram
The second battery A1 is only available in combination with the battery isolation relay J7. This prevents battery A from being drained by
consumers which are connected to the second battery. At the same time, drainage of the second battery
by the standard consumers is prevented.
J519
J7 |
SA |
S S S S S S
A1
Legend
ABattery
A1 Second battery
BStarter
J7 Battery isolation relay
J519 Onboard supply control unit
SA Fuse holder A
TV32 Jump start connection
TV32
A B
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Signal output
Ground
Signal input
Positive
CAN data bus cable
The signal cable colours shown in the illustration apply to all subsequent functional diagrams.
15
Vehicle electrical system
Jump start connections
Equipment
The Volkswagen Crafter is equipped with a positive and a negative connection for jump-starting and for charging the battery.
Positive jump start connection
To connect a jump-starting cable or a battery charger, a connection point for the positive cable is located on the left-hand side of the air filter housing in the engine compartment.
Negative jump start connection
To connect a jump-starting cable or a battery charger, a connection point for the negative cable is located on the left-hand wing in the engine compartment.
Jump start connection
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Jump start connection
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Negative main connection
The optional, main connection for the battery negative cable is located on the right next to the accelerator pedal.
The connection and the ground bolt can be separated by pulling the red actuation tab.
This enables the battery to be isolated from the vehicle electrical system if necessary or prescribed for repair work.
Main connection |
Actuation tab |
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Vehicle electrical system
Onboard supply control unit
Installation location
The onboard supply control unit (OBSCU) J519 is located, together with the fuse and relay box, on the left of the vehicle interior in the footwell beneath the instrument panel.
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Variants |
Relay box |
Onboard supply control unit |
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It is available in the following variants:
-Standard
-Low line
-Mid line and
-High line
The different variants offer various functions.
Fuse box
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Functions
Function |
Standard |
Low line |
Mid-line |
High-line |
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Exterior light control system with bulb monitoring |
X |
X |
X |
X |
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High-level brake light |
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X |
X |
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Fog lights |
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X |
X |
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Turn signal actuation |
X |
X |
X |
X |
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Interior light control system |
X |
X |
X |
X |
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Interior convenience light |
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X |
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Windscreen wiper and washer system |
X |
X |
X |
X |
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Rear window wiper and washer system |
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X |
X |
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Heated rear window |
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X |
X |
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Heated windscreen |
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X |
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Central locking: Sliding door, hinged rear door |
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X |
X |
X |
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Central locking: 2nd sliding door |
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X |
X |
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Rotary light switch input |
X |
X |
X |
X |
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Sensor signal and switch input |
X |
X |
X |
X |
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Vent windows |
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X |
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Headlight washer system |
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X |
X |
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Auxiliary turn signal module |
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X |
X |
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Alarm function |
X |
X |
X |
X |
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ATA function |
X |
X |
X |
X |
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Central locking: Front passenger door |
X |
X |
X |
X |
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Window regulator: Front passenger door |
X |
X |
X |
X |
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Vehicle electrical system
Light switch
Function
The light switch E1 is responsible for actuating the exterior light functions. The onboard supply control unit reads in the signals from the voltage-coded light switch directly.
The signals for the turn signal and main beam functions are transmitted from the steering column electronics control unit via the CAN drive data bus and the CAN convenience data bus.
S370_005
Variants
The light swicth is available in eight different variants.
Variant 1 |
Variant 2 |
Variant 3 |
Variant 4 |
Variant 5 |
Variant 6 |
Variant 7 |
Variant 8 |
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Off |
Autom. |
Off |
Autom. |
Left parking |
Left parking |
Left parking |
Left parking |
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driving |
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driving |
light |
light |
light |
light |
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lights |
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lights |
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Side light |
Off |
Side light |
Off |
Right |
Right |
Right |
Right |
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parking light |
parking light |
parking light |
parking light |
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Dipped |
Side light |
Dipped |
Side light |
Off |
Autom. |
Off |
Autom. |
beam |
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beam |
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driving |
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driving |
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lights |
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lights |
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Rear fog |
Dipped |
Rear fog |
Dipped |
Side light |
Off |
Side light |
Off |
light |
beam |
light |
beam |
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Rear fog |
Fog light |
Rear fog |
Dipped |
Side light |
Dipped |
Side light |
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light |
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light |
beam |
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beam |
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Fog light |
Rear fog |
Dipped |
Rear fog |
Dipped |
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light |
beam |
light |
beam |
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Rear fog |
Fog light |
Rear fog |
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light |
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light |
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Fog light |
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Turn signal control system
Function description
The onboard supply control unit is the master for the turn signal function and carries out the various turn signal functions. It receives all requests to actuate the turn signals, prioritises these and is the only control unit to implement a turn signal pulse on the CAN data bus. All of the other involved control units evaluate this turn signal pulse.
Turn signal actuation priority
The turn signals are actuated according to the following piority:
●1 Airbag hazard warning flashing
●2 Special alarm flashing
●3 Direction indication or hazard warning flashing
Airbag hazard warning flashing
In the event of airbag deployment, the airbag control unit transmits a CAN message to the onboard supply control unit. The hazard warning flashing function is then triggered.
●4 ATA alarm flashing
●5 Central locking feedback flashing
This function is deactivated by actuating the hazard warning lights button (E229) once or by switching the ignition off, on and off again.
Electronic ignition lock D9
Turn signal bulbs
Airbag control unit J234
Onboard supply control unit J519
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Vehicle electrical system
Special alarm flashing
The control unit for programmable special functions can request alarm flashing with a pre-specified on/off phase from the onboard supply control unit.
Depending on the way in which the control unit for programmable special functions is programmed, the following lighting facilities can be actuated in the event of special alarm flashing:
-Main beam,
-Fog lights and
-Turn signals
The special alarm flashing function is used, e.g. in emergency vehicles.
Switch
Control unit for programmable special functions
Onboard supply control unit
Bulbs
S370_009
Hazard warning flashing
The onboard supply control unit receives the hazard warning flashing signal from the control unit for middle of dash panel J819, which reads in the signals from the hazard warning lights button E229. The onboard supply control unit then actuates all turn signals.
No bulb monitoring is carried out during hazard warning flashing. The hazard warning flashing function is always operational.
Control unit for middle of dash panel
Hazard warning lights button E229
Onboard supply control unit J519
Turn signal bulbs
S370_010
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Direction indication
The signal for direction indication is received by the onboard supply control unit from the steering column electronics control unit J527, which reads in the signals from the turn signal switch E2 in voltage-coded form. The electronic ignition lock (EIL) D9 transfers the signals from the CAN drive data bus to the CAN convenience data bus. The onboard supply control unit actuates the turn signal bulbs as requested.
During direction indication, the turn signal bulbs are monitored for bulb failure.
The bulbs' flashing frequency is doubled in the event of bulb failure. Actuation of the turn signal warning lamps is carried out via the CAN convenience data bus and the control unit in the dash panel insert. The direction indication function is only active in the case of "terminal 15 on".
Steering column electronics control unit J527 |
Onboard supply control unit J519 |
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Turn signal bulbs, right |
CAN drive data bus |
CAN convenience data bus |
Turn signal switch E2 |
S370_011 |
23
Vehicle electrical system
ATA alarm flashing
The ATA alarm flashing function is active if no authorised key is located in the electronic ignition lock (EIL).
The alarm is output via the alarm horn H12 and the turn signals.
In this case, the roof electronics control unit transmits a request to the onboard supply control unit via the CAN convenience data bus. Bulb monitoring is not carried out during ATA alarm flashing.
Roof electronics control unit
Onboard supply control |
Alarm horn |
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unit |
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S370_012
Turn signals
Central locking feedback flashing
Unlocking the vehicle is indicated by all of the turn signals' flashing twice. Locking the vehicle is indicated by all of the turn signals' flashing once.
The request for central locking feedback flashing is transmitted by the electronic ignition lock via the CAN convenience data bus. This function is only active if no authorised key is located in the electronic ignition lock.
Electronic ignition lock
Onboard supply control unit
Radio remote control
S370_013
Turn signals
24
Special direction indication
The control unit for programmable special functions is able to request direction indication from the onboard supply control unit. The onboard supply control unit handles this request like a request from the steering column electronics control units, although these requests have priority.
The control unit for programmable special functions does not send a request, or ends its request, as soon as it detects a request for direction indication from the steering column electronics control unit.
Control unit for programmable special functions
Onboard supply control unit
S370_014
Turn signals
Special hazard warning flashing
The control unit for programmable special functions is able, like the control unit for middle of dash panel, to request hazard warning flashing from the onboard supply control unit.
It withdraws its request as soon as it detects a request from the control unit for middle of dash panel.
This function is deactivated either by the control unit for programmable special functions or by actuating the hazard warning lights button.
Control unit for programmable special functions
Hazard warning
lights button Control unit for middle of dash
panel
Onboard supply control unit
Turn signals |
S370_015 |
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25
Vehicle electrical system
Lighting
Parking light
The left or right side light bulbs and the left or right tail light bulbs are actuated by the onboard supply control unit.
The request to switch on the parking lights comes directly from the light switch.
The parking light function is active if no authorised key is located in the EIL.
Bulb monitoring is carried out when the parking light function is on.
Light switch
Onboard supply control unit
S370_016
Left side light bulb |
Left tail light bulb |
Side light and tail light
The left and right side and tail light bulbs are actuated by the onboard supply control unit.
The request to switch on comes directly from the light switch. The side and tail lights can also be switched on if the ignition key has been removed, in which case an acoustic signal is emitted.
Light switch
Onboard supply control unit
Side light and tail light bulbs |
S370_017 |
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