Audi A4 2001 User Manual

254

Service.

AUDI A4´01 - Technical Features

Design and Function

For internal use only.

Self-study programme 254

Advance by technology

The new Audi A4,

a vehicle which combines driving pleasure and good sense
with the highest level of quality and sports styling.

Control unit for vehicle electrical system

New engine programme

...18

Electronic stability programme with
brake assistance

...32

Steering column switch module

Crash sensors for front airbag

...48

...44

...14

Trapezium link
rear axle

...27

Aero-floor

2

...7

Multi-communication bar

...72

Contents

Page

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Occupant protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Engine and gearbox

2.0 l R4 and 3.0 l V6 engines (see SSP 255) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Innovations - 2.5 l V6 TDI engine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Innovations - automatic gearbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Running gear

Axles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Mechanical unit mountings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Brake system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Brake assistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Electrical system

Vehicle electrical system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

CAN BUS system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Dash panel insert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Steering column switch module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..44

Function circuit diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Control unit for vehicle electrical system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Function circuit diagram for "lowline" version . . . . . . . . . . . . . . . . . . . . . 50

Function circuit diagram for "highline" version . . . . . . . . . . . . . . . . . . . . 52

Convenience system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Anti-theft alarm system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Radio - chorus II, concert II and symphony II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Navigation IV and Navigation Plus-D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Multi-communication bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Electric logbook "Audi Logbook" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Heater/AC

Design and function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

7-piston compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Air conditioner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Glove compartment cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Solar roof. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Fresh air blower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Actuators/sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Functional diagram for fully automatic air conditioner . . . . . . . . . . . . . . 84

Additional heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

The self-study programme will provide you with information on
design and functions.

It is not intended as a workshop manual.

For maintenance and repair operations it is essential that you
refer to the current technical literature.

New

Important:
Note

3

Introduction

The architecture of motion

Performance and smooth running

The engine programme of the new Audi A4
includes two petrol engines of a completely
new design, with aluminium housings.
The 2.0 litre 4-cylinder in-line engine with
96 kW (130 PS) and the 3.0 litre V6 with
162 kW (220 PS) fulfil the EU 4 emissions
standard.
A high degree of running smoothness is
achieved via balancer shafts.

Infinitely variable perfection

For the first time in this vehicle class, Audi
offers the infinitely variable "multitronic"
automatic gearbox for all front-wheel drive
versions.

The new light alloy running gear

With the four-link front axle, each wheel is
controlled by four aluminium transverse links.
The pivot bearings are also made from the
same light alloy.

The trapezium link rear axle for the quattro
drive system is also used in the front-wheel
drive models of the Audi A4.

4

Finely-tuned aerodynamics

Despite the greater frontal area and the cool­ing air current for the air conditioner (stand­ard), it was possible to improve the C

value

D

by 5 %, in comparison to its predecessor,
to 0.28.

A special feature is the so-called aero-floor,
which provides for optimal airflow on the
underside of the vehicle.

High safety standards

With a thoroughly optimised body design and
comprehensive safety equipment, the new
Audi A4 is able to comply with all current valid
safety standards, throughout the world.
Crash sensors for the front airbags integrated
directly into the bumper bar, improve occu­pant protection.

SSP254_048

Electronic stability programme (ESP)
including brake assistant

For the latest ESP generation, the hydraulic
brake assistant is an integral part of the
standard equipment.
It is intended to assist the driver by automati­cally increasing the brake pressure during
emergency braking.

Communication centre on wheels

With regard to infotainment, the new
Audi A4 leaves nothing to be desired.
4 different audio systems, 2 differently config­ured Navigation systems and a car phone
with voice operation are on offer.

5

Introduction

Vehicle dimensions of Audi A4´01

1628

1528

1766

977

799

1050

921 976

257

2650

870

303

901

106/110

1526

1937

1

5

9

445 L

471

976

4527

1000

1400

1357

1088

SSP254_051

6

The aero-floor

not only contributes to improved aero­dynamics.
It was also possible to reduce the noise level
by approx. 3 dB (A).

Front-wheel drive

The aero-floor was designed so as to guaran­tee ground clearance and resistance to stone
impact and to prevent accumulation of dirt,
stones and snow.

Four-wheel drive quattro and V6 engine

Part of the additional costs generated by the
aero-floor could be compensated by dispens­ing with certain panelling components as
well as by dispensing with PVC protection of
the underside of the vehicle. The latter is of
advantage during recycling.

SSP254_053

The engine compartment noise insu­lation does not form part of the aero­floor.

7

Body

Front impact design features

The new Audi A4 is designed for optimal con­formance with current crash requirements
and safety standards.
This could only be achieved by increasing the
body weight.

In order to reduce this additional weight to a
minimum, the proportion of light-weight
materials has been increased in comparison
to its predecessor.
The proportion of high-strength sheet metal
parts as well as the use of a total of 10 large
component "tailored blanks", contribute sig­nificantly to weight reduction.
Body rigidity has been increased by 45 % by
increasing the number of connection points
by 25 %.

– the straightened longitudinal member with

crash-optimised octagonal cross-piece

– the rigid and significantly wider bumper

cross-piece

– the integration of the member structures

into the passenger cell

– strength, rigidity and weight-optimised

suspension strut cross-piece

SSP254_054

Depending upon vehicle weight, performance and fuel consumption are the characteristics
which our customers can experience at first hand.

8

Side impact design features

In the floor area, the cell consists of three
large tailored blanks, which ensure a stable
connection between the front and rear of the
vehicle.

Weight-saving optimisation of deformation
characteristics in the event of a side impact
was achieved by the use of an aluminium
extruded profile in the sill.

“tailored blanks” are made-to-measure
sheet metal parts with varying material
thickness.

SSP254_055

SSP254_056

9

Body

w

w

Doors

The doors of the Audi A4 demonstrate a sig­nificantly increased rigidity due to the one­piece door shell construction.

For the first time, a so-called spray-on noise
insulation is used, which is sprayed on as
required and allows weight reduction for the
same effectiveness.

Noise insulation

SSP254_066

In addition, the doors have been fitted with a
second weatherseal. One weatherseal is fitted
to the door and the other is fitted to the body.

The new door concept permits a reduction in
the overall noise level of a further 3 dB (A) and
thus contributes to improving the aero-acous­tics.

SSP254_067

The newly developed sub-frame is bolted to
the door shell via fitted bolts.

Roof

Roof trim strip

Door windo
seal

Door windo

Door trim

Door seal

Door frame

Door frame seal

SSP254_075

Emergency door locking

In the event of failure of the central locking,
e.g. due to power supply faults, each door can
be individually locked without using the lock
cylinder.

Firstly, with the door open, the cap must be
removed. Emergency locking is effected by
inserting the ignition key.

After the door has been closed, it is not possi­ble to open it from the outside.
The door can be opened from the inside by
actuating the door release handle twice.

SSP254_069

Luggage compartment lid

The luggage compartment lid should always
be operated via the radio remote control.

The lock cylinder for the luggage compart­ment lid is integrated into the handle.

Continuous locking of luggage compartment

If the lock cylinder is in the horizontal posi­tion with the key removed, the luggage com­partment lid is no longer included in the
central locking system. Opening is then only
possible via the centre unlocking button of
the radio remote control.

When the lock cylinder is in the vertical posi­tion, the lid is an integral part of the central
locking system.

SSP254_070

Manual unlocking and opening

is effected by turning the key to the left.
In this position, it is not possible to remove
the key, which must subsequently be returned
to the vertical position.
Thus, it is ensured that the luggage compart­ment lid is an integral part of the central lock­ing system.

SSP254_071

SSP254_072

11

Occupant protection

Overview of system

J285/K75

J533

T16

J393

G 283

J162

N95

J220

J234

G 284

J526

K145

AIRBAG

OFF

N131

AIRBAG

AUS

E224

EIN

12

N277

G 256

G179

N199

N153

N201

N200

N154

N202

G180

N278

G 257

SSP254_029

To complement the comprehensive body
modifications, occupant protection has been
improved through the further development of
the familiar 8.4 airbag system.

The new generation bears the designa­tion 8.4 E, where the E stands for
"extended".

The position of the sensors is selected so that
they are installed as near as possible to the
outer structure of the vehicle.
This enables quicker deceleration detection in
the event of an impact.

The system comprises driver/passenger air­bags, front side airbags, optional rear side
airbags, SIDEGUARDS

®

, three point front seat
belts with ball tensioners and belt force limit­ers, three point rear outer seat belts, centre
lap belt (for fixed rear seat bench), Isofix pre­paration in rear of vehicle, and a total of 6
non-central accelerometers:

– 2 front impact crash sensors
– 2 driver/passenger side airbag crash sen-

sors, (in the B-pillar for side impact)

– 2 driver/passenger rear side airbag crash

sensors, (on the C-pillar for side impact)

The external sensors deliver digitised acceler­ation data to the airbag control unit, which is
then evaluated in the control unit and which
triggers the relevant restraint system compo­nents.

Key

E224 Key switch for switching off

passenger’s side airbag

G179 Side airbag crash sensor, driver’s

side (B-pillar)

G180 Side airbag crash sensor, passenger’s

side (B-pillar)

G256 Crash sensor for rear side airbag,

driver’s side

G257 Crash sensor for rear side airbag,

passenger's side

G283 Front airbag crash sensor, driver’s

side

G284 Front airbag crash sensor,

passenger’s side
J162 Heater control unit
J220 Control unit for motronic
J234 Airbag control unit
J285 Control unit with display unit in

dash panel insert
J393 Central control unit for convenience

system
J526 Control unit for telephone /

telematics
J533 Diagnosis interface for data bus

(Gateway)

K75 Airbag warning lamp
K145 "Airbag off" warning lamp,

passenger's side
N95 Airbag igniter, driver's side
N131 Airbag igniter 1, passenger's side
N153 Igniter for belt tensioner, driver's side
N154 Igniter for belt tensioner,

passenger's side
N199 Igniter for side airbag, driver’s side
N200 Igniter for side airbag, passenger's

side

N201 Igniter for rear side airbag,

driver’s side
N202 Igniter for rear side airbag,

passenger's side
N277 Igniter for airbag in B-pillar

(SIDEGUARD

®

), driver's side

N278 Igniter for airbag in B-pillar

(SIDEGUARD

®

), passenger's side

T16 Connector, 16-pin, diagnosis

connection

13

Occupant protection

Crash sensors for front airbag G283, 284

Both sensors for front impact detection func­tion in conjunction with the crash sensor and
the safe sensor which are integrated into the
airbag control unit J234.

If a certain signal threshold is exceeded in the
front airbag crash sensor, a threshold reduc­tion is activated in the airbag control unit,
which results in a shorter triggering time.

Upper body

Head

Deceleration load

Impact

Belt force limiter

Front airbags inflated

Triggering of front airbags

Triggering of belt tensioners

Damping function

response in

response

Time [ms]

SSP254_058

the steering column

Vehicle rebound

SSP254_063

14

SSP254_064

Crash sensors for side airbags
G179, 180, 256, 257

In order to trigger the components of the
restraint system, two simultaneous impact
detection signals are required for the plausi­bility check:

– from both opposing crash sensors

(B-pillar left with right and/or
(C-pillar left with right) and

– from the control unit internal crash sen-

sors.

The crash sensors are designed in such a way
that incorrect installation is excluded.

Airbag control unit J234

The warning lamp for airbag K75 is activated
continuously following a detected impact.
"CRASH DATA STORED" and the triggered
components are displayed with fault code
during fault memory readout.

SSP254_059

Re-encoding of the airbag control unit is no
longer possible after the first crash data mes­sage is stored.

Triggering is performed in two thresholds
depending upon the deceleration value:

– Threshold 1 = belt tensioners only
– Threshold 2 = belt tensioners and airbag(s)

Sensors and components to be replaced
following an accident, are listed in the
current workshop manual.

15

Occupant protection

a

a

a

a

a

Deactivation of passenger airbag

Deactivation of the passenger airbag is only
possible via the key switch. In the Audi A4, the
passenger's side airbag is also deactivated.
Deactivation via the diagnostic tester is not
possible.

If a customer requires the deactivation func­tion where a key switch is not fitted, this can
only be achieved by retrofitting the key switch
and airbag OFF lamp and by re-encoding of
the airbag control unit.

Front belt attachment

Belt lock and strap fastenings are perma­nently connected to the seat frame. Thus, in
conjunction with the seat belt height adjuster,
an optimal belt fitting can be achieved for
each seat position.

SSP254_101

SSP254_011

Front head restraints

In order to offer a high degree of occupant
protection in conjunction with the seat belt
and airbag, the front head restraints have
been supplemented by an integral locking
mechanism.

SSP254_102

16

Crash signal processing

There are two separate crash signal outputs:

One crash signal is output via the conven­tional wiring and triggers the following func­tions:

– Transmitting an emergency call via the

control unit for telephone/telematics J526

(optional)
– unlocking the vehicle,
– Switch on interior light

(switch must be set to door contact),
– switching on hazard warning lights via the

central convenience electronics J393.

The auxiliary heater J162 (optional) is

switched off by the central convenience

electronics J393 via a CAN convenience

message.

The second crash signal output functions via
the convenience CAN bus, which switches off
the engine fuel supply via the engine control
unit J220.

17

Engine and gearbox

Engine

The 4-cylinder, 2.0 l engine

provides high propulsive force due to the

maximum torque of 195 Nm at 3300 rpm.

SSP254_038

The 3,0 l V6 engine

with five-valve cylinder head, produces162 kW
(220 PS) at 6300 rpm from 2976 cm
The maximum torque of 300 Nm is developed
at 3200 rpm.

3

.

Torque [Nm]

Engine speed in rpm

Power output [kW]

SSP254_060

18

SSP254_030

Torque [Nm]

Engine speed in rpm

Detailed information on these engines
can be found in SSP 255.

SSP254_061

Power output [kW]

Innovations 2.5 l V6 TDI engine

SSP255_045

Technical data

Capacity: 2496 cm

Bore: 78.3 mm

Stroke: 86.4 mm

Compression: 18.5 : 1

3

Injection system: Bosch VE VP 44 S3.5

Turbocharger: VNT 20

Exhaust emissions class: EU 3

Consumption: urban 11.0 l/100 km
(6-gear, quattro) country 6.1 l/100 km

Power output: 132 kW (180 PS)

Torque: 370 Nm at 1500 rpm

The main features of the basic engine are the
same as those of the familiar V6 TDI engine
with 132 kW (180 PS).

Torque [Nm]

Engine speed in rpm

SSP255_039

Power output [kW]

average 7.8 l/100 km

The injection system was modified in order to
reduce exhaust gas and particle emissions.

Power output and torque curve values could
be maintained under conditions which were
well within EU 3 limit values.

Limit value [%]

NOx

HC+NOx

CO

EU 3 limit values 100 %

Particle = 0.05 g/km
CO = 0.64 g/km
HC+NOx = 0.56 g/km
NOx = 0.50 g/km

Particle

SSP255_038

19

Engine and gearbox

Injection pump VP 44 S3.5

Distributor bushing

Distributor shaft

Forced flush
return

Supply piston

Thermal shoulder

Forced flush feed

The high pressure section of the injection

pump has been redesigned with regard to

pressure levels and quicker solenoid valve

actuation.

The injection pressure at part throttle has

been increased by the following measures:

Solenoid valve

SSP255_040

In order to initiate pre-injection for cold and
warm engines, the solenoid valve dynamics
have been significantly increased.
The associated increased heat generation in
the solenoid valve, is compensated by
improved fuel flow and optimal filling of the
high pressure section is achieved.

– increased cam stroke from 3.5 to 4.0 mm

– more stable support structure for high

pressure section on pump body

– conversion from 3 pistons with a diameter

of 6.0 mm, to 2 pistons with a diameter of

7.0 mm.

By reducing the number of high-pressure pis-

tons from 3 to 2, it was possible to reduce

high-pressure leakage via the sealing sur-

faces.

20

Noise levels have been significantly improved
by the pre-injection for cold and warm opera­tion and the use of dual-spring nozzle hold­ers.

Previously, pre-injection via the solenoid
valve was only realised during the engine
warm-up phase.

Injector

For the first time, an ICU injector ( I nverse C av­ity U ndercut) is used, which has a dual needle
guide.

The advantage of this ICU geometry is a sig­nificantly improved spray formation, espe­cially in the part throttle range for small
injection quantities and short needle lift.

Due to the improved spray formation through
the use of the ICU injector, it was possible to
reduce the exhaust emissions and the particle
values by up to 20 %.

ICU seat geometry

SSP255_041

Dual needle guide

ICU seat geometry Standard seat geometry

SSP255_042

21

Engine and gearbox

Charge air cooler

Through duct

Cooling duct section

The existing series connection of the two

charge air coolers for the 110 kW engine is

inadequate for the 132 kW engine with its

high air throughput.

A new charge air cooler design was devel-

oped, in order to ensure optimal charge air

flow.

22

SSP255_043

The charge air cooler design comprises two
sections, in which part of the charge air is fed
via a through duct, connected to a space-sav­ing pipe, to the section of the other charge air
cooler which is fitted with cooling fins.
The rest of the charge air is fed directly
through the cooling fins, via a separate pipe,
to the second charge air cooler and into the
through duct.

Innovations - automatic
gearbox

5-speed 01V automatic gearbox

The Audi A4 quattro MJ01 with 5-speed auto­matic gearbox features a new shift lever gate,
together with a new shifting concept.

The existing selector lever positions, 4,3,2 are
discontinued and are replaced by the "S"
position.

Gearshift positions 4,3,2 have been discontin­ued as they are hardly ever used in practice.
The DSP (dynamic shift programme) and "tip­tronic" function have basically rendered them
superfluous.

P

R

N

D

S

+

With the selector lever is in the "S" position, a
sports shift programme provides the relevant
driving dynamics. In position "S", the DSP
also provides for adaptation of the driving set
values to the driving conditions.

The introduction of the "S" programme ena­bles a significant extension of the useful shift
range between economy and sports.

The "S" programme comprises the following
special features:

– If, during driving with constant accelerator

pedal position, the selector lever is set to

the "S" position, the system always shifts

down, within defined limits.
– In order to achieve a direct driving reaction

in response to accelerator pedal actuation,

the converter clutch is closed during driv-

ing operation, where possible.
– If, in conjunction with the overall gearbox

ratio, 5th gear is designed as overdrive

gear (overdrive, 4+E), only 1st -4th gears

are shifted.

SSP254_117

Example: Dynamics code 40

Shift map 1

We recommend the multi-function steering
wheel (available as optional extra) with steer­ing wheel "tiptronic" ("thumb shifting").

Throttle valve angle [%]

Gearbox output speed [rpm]

D - normal driving programme
S - sports driving programme

SSP254_103

23

Engine and gearbox

"multitronic" and 5-speed automatic gearbox

An innovation for all automatic gearboxes is

the "Tip in D " function. This means that the

steering wheel "tiptronic" function is now

also available in selector lever position "D".

The transition to the "tiptronic" function is

effected by actuating one of the two tip

switches on the multi-function steering wheel

(selector lever in position "D"). The system

then switches to the "tiptronic" function for

approx. 10 seconds. All gears can be shifted

within the range of permissible engine

speeds.

The system returns to normal automatic oper-

ation approx. 10 seconds after the last tip

request.

SSP254_088

Special feature:

The countdown from approx. 10 seconds to
return to normal automatic operation is inter­rupted, in the event that cornering is detected
or the vehicle is in overrun operation.

When normal driving conditions are detected
again, the countdown recommences from
approx. 10 seconds.

24

Notes

25

Running gear

Axles

Four-link front axle

The thorough further development of the

light-weight construction resulted in a weight

reduction of approx. 8.5 kg at the front axle.

In addition to all transverse links, the pivot

bearing is now also made of aluminium.

The wheel bearing is attached to the pivot

bearing via four bolts. The wheel hub can be

pressed in and out.

Aluminium
spring plate

SSP254_086

Aluminium mounting bracket

Shock absorber valves

SSP254_087

Aluminium pivot bearing

The suspension strut mounting is of the bulky

rubber bearing construction.

It consists of two functional components:

– The inner part forms the connection to the

piston rod.

– The larger outer part provides for acoustic

insulation of the shock absorber.

26

SSP254_085

Trapezium link rear axle

The rear axle design with largely identical
components is used in both the front-wheel
drive as well as in the quattro versions.

SSP254_089

Toe adjustment

The front-wheel drive version is fitted with a
wheel bearing unit with integral wheel hub,
which is mounted on a stub axle forged
together with the wheel carrier.

Apart from the axle mounting, the two axle
versions differ only in the wheel carrier and
the wheel bearings.

Camber
adjustment

SSP254_091

Toe adjustment

The wheel bearings of the quattro version
consist of pressed-in, double-row angular ball
bearings with conventional wheel hubs.

SSP254_083

Camber
adjustment

SSP254_082

27

Running gear

Mechanical unit mountings

Engine mounting 1

Cross member

Torque
member

Engine
mounting 2

A newly designed three-point mechanical unit

mounting is used in the new Audi A4.

The hydraulically damped engine mountings

(electrically-controlled version for diesel

engines) are fastened directly to the longitu-

dinal members via die-cast aluminium brack-

ets.

The gearbox mounting is effected by means

of a conventional rubber bearing on a body-

mounted aluminium carrier, which is pro-

duced according to the hollow sand casting

technique.

Gearbox
mounting 3

SSP254_107

The additional cross member enables support
over a longer lever arm, which positively influ­ences vibration and load cycle characteristics.

The aluminium cross member is bolted to the
body as well as to the rear subframe mount­ings and, in addition to its supporting func­tion for the gearbox mounting, serves as a
body-stiffening tunnel bridge.

28

The three-point mechanical unit mount­ing is used for all engine/gearbox
combinations except those including
the 01V 5-speed automatic gearbox.

Brake system

The new Bosch ESP 5.7 is introduced in the
Audi A4. The ESP 5.7 is distinguished by the
following special features:

– The hydraulic unit and control unit form a

single unit.

– The charging pump (actuation of ESP

hydraulic pump V156) is discontinued.

– A brake assistant is included.

Hydraulic modulator

Due to the increased brake fluid viscosity at
extremely low ambient temperatures, the
required delivery rate for the return pump for
ABS V39 could not be achieved without a
charging pump (resulting from the increased
suction resistance in the system).

The purpose of the development of the
ESP 5.7 was to improve the suction of the ABS
return pump so that the charging pump was
no longer necessary.

The charging pump could be discontinued
through the use of a two-stage ABS return
pump, enlarging the cross-section of the
brake lines and the use of a larger-dimen­sioned central valve in the brake master cylin­der.

SSP254_094

29

Running gear

Single-stage ABS return pump

Suction volumes

The graphic shows a comparison of the

suction volumes of both pump versions.

In the single-stage ABS return pump, the

entire suction volume must be drawn in and

flow through the suction line during one

piston stroke (piston stroke from TDC to BDC).

Suction volumes

SSP254_095

The suction pressure is correspondingly high
and increases with increasing viscosity.
Cavitation and the associated drop in
performance on the pressure side, are the
results.

30

Two-stage ABS return pump

Working chamber 1

Working chamber 2

Suction volumes

The piston of the two-stage ABS return pump
is stepped and has a double-acting function
within two working chambers.

Suction is effected in two stages; brake fluid
being drawn through the suction line during
each piston stroke.

Function:

If the piston moves from BDC to TDC, the
brake fluid in working chamber 1 is com­pressed whereas working chamber 2 is simul­taneously under suction.

If the piston then moves from
TDC to BDC, the brake fluid which has been
drawn into working chamber 2 is forced back
into the suction line against the inlet valve.

SSP254_096

As the entire suction volume is supplied
almost continuously, the maximum suction
flow rate is significantly lower, which dimin­ishes the suction pressure and prevents
cavitation.
Thus, a quick pressure build-up is ensured,
even at extremely low temperatures.

In working chamber 1, brake fluid is now
drawn via the open inlet valve, out of the suc­tion line and out of the connection line to
working chamber 2.

The suction flow rate in the suction line is
diminished by that amount which flows back
out of the connection line from working
chamber 2
(drawn in during previous working operation).

31

Running gear

Brake assistant

Investigations in accident research have

shown, that the majority of drivers fail to ade-

quately actuate the brakes in an emergency

situation.

This results in insufficient brake pressure

being generated to achieve maximum vehicle

deceleration.

This lengthens the braking distance.

Brake servo pressure sensor G294 is used for

detection of emergency braking.

Pressure sensor G294

During emergency braking, the brake assist­ant aids the driver by increasing the brake
pressure automatically, to a level exceeding
the locking limit.
The ABS ( A nti-lock b raking s ystem) is thus
quickly brought into the operating range,
which enables a maximum vehicle decelera­tion to be achieved.

For this purpose, the pressure increase gradi-

ent (pressure build-up with respect to time) is

evaluated and, if necessary, the brake assist-

ant is activated.

SSP254_093

Pressure [p]

Time [t]

SSP254_092

Emergency braking

32

Normal braking distance

The function of the brake assistant is
sub-divided into 2 phases:

• Phase 1

If the pressure increase gradient exceeds a
specified value (emergency braking), the ABS
return pump and the relevant solenoid valve
are activated by the ESP control unit and the
brake pressure is thus increased into the ABS

• Phase 2

If the pressure determined by the driver falls
below a certain value after triggering of the
brake assistant, the system pressure is
restored to the pedal pressure determined by

the driver.
control range, in a similar manner to that of
the control system for an electronic differen­tial lock.

Brake assistant activated Brake pedal unloaded Brake assistant

switches off

Phase 1

Phase 2

Brake pressure [p]

Time [t]

Brake pressure determined by an
experienced driver

Regulated brake pressure
(brake assistant)

Determined brake pressure
insufficient inexperienced driver

ABS control
range

SSP254_084

The integral inlet and outlet valves in the
hydraulic modulator are no longer sim­ply switched on/off, but are regulated
via supplied voltage.
This enables more precise control on
extremely slippery surfaces, e.g. ice.

33

Running gear

Brake fluid reservoir

The brake fluid reservoir is secured with an
additional screw.

The new maintenance opening in the brake
fluid reservoir enables the extraction of brake
fluid from both brake fluid chambers.

The new brake filler and bleeder unit
VAS 5234 must be used for this purpose.

Maintenance opening

Brake light switch

The fastening and adjustment of the brake
light switch are new.

The brake light switch is secured to the pedal
bracket via a bayonet fitting.

The position of the push rod is adjusted for
the basic setting.

For this purpose, the brake light switch must
be released by turning it anti-clockwise.
The push rod catch is released simultane­ously via the locking lug.

SSP254_098

Fastening screw

The push rod is now free and can be adjusted
without risk of damage.

The push rod is pulled out to the stop for the
basic setting.
The brake light switch can now be inserted
into the pedal bracket and secured by turning
clockwise. At the same time, the push rod
catch is locked automatically by means of the
locking lug.

34

SSP254_099

Notes

35

Electrical system

Vehicle electrical system

Control unit for
telematics J499

Control unit for
mobile phone control
electronics J412

Battery

Control unit with
display in dash panel
insert J285

Control unit for headlamp
range control J431

Chip card
reader R99

Control unit for
coolant fan,
Stage 1+2 J293

Front airbag crash sen­sor, driver’s side G283

Front airbag crash
sensor, passen­ger’s side G284

Control unit
for ESP J104

Control unit
for Motronic J220
Control unit for auto­matic gearbox J217

Steering column
switch module J527

36

Side airbag crash sensor,
passenger’s side G180

Door control units,
passenger side J387
rear right,
optional J389

Side airbag crash sensor, rear
driver’s side G256
passenger’s side G257

Control unit for trailer
recognition J345

Control unit for
parking aid J446

ESP sensor

Control unit for
tyre pressure
monitor J502

Airbag control
unit J234

Central control unit for
convenience system J393

Side airbag crash sensor,
driver’s side G179

Control unit for vehicle electri­cal system J519

SSP254_008

Door control unit,
driver’s side J386,
rear left, optional J388

37

Electrical system

CAN BUS networking

J285

Gate­ way

Diagnosis system

J507

J220

J217

J234

J104

J386

J388

J393

E87

J387

J389

J502

J162

J526

TRACK
SEEK

CD CDC

123456

1

2

AM

EJECT

12

FM

BASS MIDDLE TREBLE BALANCE FADER

PLAY SDE

TAPE

R99

J499

EJECT

Audi symphony

R

FR FF

TUNE SCAN

AS

TP

DOLBY SYSTEM

RDS

RANDOM

38

NOX sensor
(USA only)

J345

J527

J519

G85

The ignition switch signals and the
control buttons for multifunction
and "tiptronic" steering wheel are
registered via the steering column
electronics.

J527

J446

J401

J402

J136

R94

+

-

R
T

J453

CAN data bus

The Audi A4 is equipped with a widely
extended CAN data bus system.

Due to the ever increasing number of control
units installed in the vehicle and the associ­ated requirement for data exchange, the
importance of the CAN data bus system
increases significantly.

For communication between the
installed control units and the diagnos­tic tester, two diagnosis wires (K and L)
are available.

G85 Steering angle sender
E87 Operating and display unit for

air conditioner
J104 Control unit for ESP
J136 Control unit for seat adjustment with

memory, optional
J162 Auxiliary heater, optional
J217 Control unit for automatic gearbox
J220 Control unit for motronic
J234 Airbag control unit
J285 Control unit with display unit in

dash panel insert
J345 Control unit for trailer recognition
J386 Door control unit, driver’s side
J387 Door control unit, passenger side
J388 Rear left door control unit, optional
J389 Rear right door control unit, optional
J393 Central control unit for convenience

system
J401 Navigation system control unit

J402 Control unit for operating electronics,

navigation, TV tuner
J446 Control unit for parking aid
J453 Control unit for multi-function

steering wheel
J499 Control unit for telematics
J502 Control unit for tyre pressure monitor
J507 Control unit for speech entry
J519 Control unit for vehicle electrical

system
J526 Control unit for telephone -

permanent installation
J527 Control unit for steering column

electronics
R Radio
R94 Interface for navigation
R99 Chip card reader

Drive BUS 500 kBaud
Convenience BUS 100 kBaud
Display BUS 100 kBaud
Diagnosis connection
K wire
Diagnosis connection
L wire (2nd K wire)

The newly developed adapter VAS 6017 ena­bles communication with all control units.

SSP254_112

Electrical system

Dash panel insert

Cruise control system ON

Auto-check system

Setting buttons for digital clock,
date and instrument illumination

There are two dash panel insert versions:

– "lowline"
– "highline"

The "highline" version is equipped with a
high-quality colour display for the driver infor­mation system and is installed in vehicles
with navigation systems as well as telematics.

SSP254_012

Call-up button for
service interval
indicator

The dash panel insert of the new Audi A4 is
equipped with

– the gateway for linking the three data bus

systems: drive, convenience, information

– and the immobiliser III.

Reset button for trip
recorder

40

User prompt in the centre display via the con­trol switch in the centre console, is only avail­able in vehicles with

– navigation system ("highline" version only)

and/or
– telematics and/or
– auxiliary heater and/or
– tyre pressure monitoring.

The optional driver information system
includes the following functions:

– radio clock
– auto-check system
– on-board computer.

The km range is indicated in the basic ver­sion.

In order to ensure good signal reception for
the radio clock, the receiver is installed in the
rear bumper bar.

SSP254_104

V

5

+

th

r

a

E

io

d

a

R

sig

l

a

n

SSP254_108

41

Electrical system

A new feature of the Auto-Check system

is the position-dependent bulb monitor display.

The fault message is transmitted from the vehi-

cle electrical system control unit J519, via the

convenience data bus, to the dash panel insert

J285 and appears on the centre display.

Control unit with
display unit in dash
panel processor J285

Convenience data
bus

Control unit for vehicle

electrical system J519

SSP254_125

The Audi A4 quattro is equipped with two fuel

gauge senders G and G169.

SSP254_118

Sender G registers the lower, and sender

G169 the upper partial volume in the fuel

tank.

The signals from senders G and G169 are

evaluated separately. The calculated litre

values are then added and displayed.

42

Fuel gauge
sender G

SSP254_123

Fuel gauge
sender 2, G169

Diagnostics

Convenience data
bus

Control unit with
display unit in
dash panel insert J285

Control unit for steering
column electronics J527

Ignition lock D

The dash panel insert checks the plausibility

– of both fuel gauge senders in quattro

vehicles
– as well as the terminal 15 input signal.

Terminal 15

SSP254_138

Due to the gateway function of the dash panel
insert, the communication with the individual
control units connected to the CAN data bus
is checked during diagnosis.

Communication faults are entered into the
fault memory. The current status can be read
in the measured value blocks.

A further innovation is the display of the max­imum and minimum engine oil levels in the
measured value block after the most recent
service operation.

The adaptation of the mileage/kilometre read­ing after replacement of the dash panel
insert, is possible (several attempts) up to a
recorded distance of 5 km after installation.

43

Electrical system

Steering column switch

module

Due to the compact design of the newly

developed steering column switch module, it

was possible to minimise the amount of wir-

ing necessary and the space requirements.

A self-diagnosis facility for the steering col-

umn switch is now available with new switch

module.

The steering column switch module consists

of the following components:

Steering column
electronics J527

– Turn signal switch

– Wiper switch with interval potentiometer

– Separate steering column switch cruise

control system operation
– Coil spring for diver's airbag
– Steering angle sensor for ESP
– Steering column electronics for signal con-

version and processing of drive and con-

venience CAN BUS J527

In addition, the steering column electronics
register the ignition switch signals.
Furthermore, the control buttons for multi­function and "tiptronic" steering wheel are
registered via the steering wheel electronics
module.

Steering column switch

Detection of the respective switch positions is
effected via voltage coding, using various
resistance values in the relevant position. The
steering column electronics evaluates this
switch information and transmits it, via the
convenience CAN BUS, to the vehicle electri­cal system control unit J519.

Turn signal
switch E2

Cruise control
system E45

Cruise control system (CCS)

For ergonomic reasons, the control switch for
the cruise control system is located on the
left side of the steering column, below the
turn signal lever.

Warning lamp K31 in the dash panel insert
illuminates when the CCS is in control mode.

The modified operation of the CCS Steering
column switch function is described in the
Owner's Manual.

44

Ignition
steering lock

SSP254_105

Wiper

switch E

Steering angle
sensor G85

Ignition lock registration

The signals from the terminals:

– P parking light
– 86s ignition key contact
– 75 Load-reduction relay
– 15 ignition ON
– 50 starter

are transmitted to the steering column elec­tronics J527 via conventional wiring. The
switch positions of the ignition lock are pre­pared by the electronics, supplied to the con­venience CAN bus and then transmitted via
the gateway to the drive and infotainment
CAN bus systems.

Steering angle sender G85

The determination of steering angle is per­formed via optical elements in the steering

Coil spring

column electronics J527 and is supplied to
the drive CAN BUS.
The current steering angle position is thus
made available to the ESP control unit.

For further information on the optical
steering angle sensor, please refer to
SSP 204.

Self-diagnosis

Communication between the diagnostic
tester and the steering column electronics
J527 is effected by means of the convenience

R

T

data bus via the central convenience electron­ics J393, as no separate K wire is connected
to the steering column electronics.. (see
graphic 254 018 on Page 57)

Steering column electronics
module J453 with operating
unit E221

The steering column switch module
must always be coded.

SSP254_014

The steering column electronics module with
operating unit for "tiptronic", multi-functions,
horn etc., is incorporated in the self-diagnosis.

Address word 16

After the addressing, the tester answers with
the text "steering column electronics".

45

Electrical system

Functional diagram
Steering column switch
module
(maximum equipment)

Colour coding

Components

E Windscreen wiper switch
E2 Turn signal switch
E45 CCS switch
E221 Operating unit in steering wheel
G85 Steering angle sender
H Horn actuation
J234 Airbag control unit
J453 Control unit for multi-function

steering wheel

J527 Control unit for steering column

electronics
S Fuse
Z36 Heated steering wheel

Auxiliary signals

= Input signal

= Output signal

= Positive power supply

= Earth

= CAN-BUS

1 CAN screen drive

2 Emergency vehicle distress radio

3 Emergency vehicle radio

4 Cruise control system on/off

5 CAN low convenience

6 CAN high convenience

7 CAN low drive

8 CAN high drive

9 Ignition lock terminal 75

10 Ignition lock S contact

11 Ignition lock terminal 15

12 Ignition lock terminal 50

46

13 Ignition lock terminal P

X

{

Y Connection within the functional

diagram

Z

S13/
10A

+

R/T

H

G85

Z36

J453

E221

1 2 3 4 5 6 7 8

Z

Y

J234

J527

Z

X

X

Y

31

10

9

E45

E

E2

in out

11

12 13

31

Electrical system

Control unit for vehicle
electrical system J519

The control unit for vehicle electrical system
J519 is the newly developed electronic central
electrics and comprises a comprehensive
self-diagnosis, which can be selected directly
with address word 09.

The control unit for vehicle electrical system
receives the input signals from the conven­ience CAN BUS via the steering column
switch module or the rotary light control.

Control unit for
speech entry J507

P
b

1

1

J

J

0

0

9

9

1

1

5

5

1

1

0

0

5

5

A

A

C

C

Power supply

Control unit for
vehicle electri­cal system J519

The power connections for the individual con­sumers are driven via semi-conductor ele­ments, e.g. transistors.
A separate supply is not required, as this is
provided by the internal electronics in the
event of a fault.

J4

Dual tone­horn H2/H4

Wiper system

Hazard warning lights switch E3

Rotary light control E1

Steering col­umn electron­ics J527

48

Lighting system

Relay for
X contact J18

Control unit for trailer
recognition J345

SSP254_068

Dash panel insert J285

There are three control unit versions:

– "lowline" for the standard version
– "lowline" for vehicles with headlight

washer system

– "highline" for vehicles with driver informa-

tion system

The following functions are available with the
"lowline" version:

– Wash/wipe control and interval
– Hazard warning and turn signal control
– Actuation of horn and load-reduction relay
– Parking light left/right
– Side light left/right
– Main beam left/right and headlight flasher
– Number plate light

Light control

In the highline version, light control is trans­mitted from the steering column switch
module or directly from the rotary light
control, via the convenience data bus, to the
vehicle electrical system control unit.

The "highline" version implements the driver
information system function and also
performs the following control functions:

– Driving light and dipped beam left/right,
– Fog lights and rear lights,
– Reversing lights,
– Brake lights

with separate outputs to each of the individ­ual consumers.

Side lights

Dipped beam

Control unit for
vehicle electrical
system J519

Fog lights

Rear fog lights

Parking lights

Main beam

Headlight flasher

*

In the "lowline" version, the components marked with
an asterisk are connected via conventional wiring and
fuses, directly to the lighting units.

*

*

*

49

Electrical system

Functional diagram
Control unit for vehicle
electrical system J519

"lowline" version

Components

V11 Pump for headlight washer

E1 Light switch
E3 Hazard warning light switch
F Brake light switch
F4 Reversing light switch
F216 Contact switch for switchable

rear fog lights
H2 Treble horn
H7 Bass horn
J4 Relay for dual tone horn
J59 Load-reduction relay for x contact
J345 Control unit for trailer recognition
J446 Control unit for parking aid
J519 Control unit for vehicle electrical

system
L22 Bulb for fog light, left
L23 Bulb for fog light, right
L46 Bulb for rear fog light, left
L47 Bulb for rear fog light, right
M1 Bulb for side light, left
M2 Bulb for rear light, right
M3 Bulb for side light, right
M4 Bulb for rear light, left
M5 Bulb for turn signal light, front left
M6 Bulb for turn signal light, rear left
M7 Bulb for turn signal light, front right
M8 Bulb for turn signal light, rear right
M9 Bulb for brake light, left
M10 Bulb for brake light, right
M16 Bulb for reversing light, left
M17 Bulb for reversing light, right
M18 Bulb for side turn signal light, left
M19 Bulb for side turn signal light, right
M25 Bulb for high-level brake light
M29 Bulb for dipped beam headlight, left
M30 Bulb for main beam headlight, left
M31 Bulb for dipped beam headlight, right
M32 Bulb for main beam headlight, right
S Fuses
U10 Socket for trailer operation
V Windscreen wiper motor
V5 Windscreen washer pump

V48 Servo motor for headlight range

V49 Servo motor for headlight range

X Number plate lights

Colour coding

Auxiliary signals

1 CAN high convenience

2 CAN low convenience

3 Terminal 75

4 not fitted with trailer coupling

5 only with trailer coupling

6 Automatic gearbox "multitronic"

7 Manual gearbox

A

U

X

conditioning system

control, left

control, right

= Input signal

= Output signal

= Positive power supply

= Earth

= CAN-BUS

{

Connection within the
functional diagram

50

Y

Z

30

X

S36
30A

S37
20A

J59

E1

S19
15A

1

0

2

58s

X

Z

Y

4

S14
10A

U

F

M25

L47 M17 M10 M2 M8 M19 M7 M3 M32 M31 V49

5

S20
15A

L22 L23

H2

S40
25A

H7

J4

Z

J519

X

S21
15A

15

S27
30A

30

S77
30A

15

A

5

6

Y

3

J446

1

2

A

5

J345

U

5

7

M M

F4XX VE3

L46 M16 M9 M4 M6 M18 M5 M1 M30 M29 V48 V5 V11

M

F216

U10

in out

Electrical system

Functional diagram
Control unit for vehicle
electrical system J519

"highline" version

Components

V11 Pump for headlight washer
E1 Light switch
E3 Hazard warning light switch
F Brake light switch
F216 Contact switch for switchable

rear fog lights
H2 Treble horn
H7 Bass horn
J4 Relay for dual tone horn
J59 Load-reduction relay for x contact
J345 Control unit for trailer recognition
J446 Control unit for parking aid
J519 Control unit for vehicle electrical

system
L22 Bulb for fog light, left
L23 Bulb for fog light, right
L46 Bulb for rear fog light, left
L47 Bulb for rear fog light, right
M1 Bulb for side light, left
M2 Bulb for rear light, right
M3 Bulb for side light, right
M4 Bulb for rear light, left
M5 Bulb for turn signal light, front left
M6 Bulb for turn signal light, rear left
M7 Bulb for turn signal light, front right
M8 Bulb for turn signal light, rear right
M9 Bulb for brake light, left
M10 Bulb for brake light, right
M16 Bulb for reversing light, left
M17 Bulb for reversing light, right
M18 Bulb for side turn signal light, left
M19 Bulb for side turn signal light, right
M25 Bulb for high-level brake light
M29 Bulb for dipped beam headlight, left
M30 Bulb for main beam headlight, left
M31 Bulb for dipped beam headlight, right
M32 Bulb for main beam headlight, right
S Fuses
U10 Socket for trailer operation
V Windscreen wiper motor
V5 Windscreen washer pump

V48 Servo motor for headlight range

V49 Servo motor for headlight range

X Number plate light

Colour coding

Auxiliary signals

1 CAN high convenience

2 CAN low convenience

3 Terminal 75

4 Terminal 31

U Connection within the functional

conditioning system

control, left

control, right

= Input signal

= Output signal

= Positive power supply

= Earth

= CAN-BUS

diagram

52

30

15

S36
30A

S37
20A

J59

E1

0

H2
S14
10A

S7
10A

S40
25A

H7

1

2

A

15

58s

F

M25

L47 M17 M10 M2 M8 M19 M7 M3 M32 M31 V49

M2

L22 L23

J4

U

3

J446

J519

30

S27

15

J345

2

1

30A

U

S77
30A

M M

M

4

XX VE3

L46 M16 M9 M4 M6 M18 M5 M1 M30 M29 V48 V5 V11

M4

F216

U10

in out

Electrical system

In the "highline" version of the vehicle electri­cal system control unit, only the 21 watt
filament of the two-phase bulb for the brake
and rear light is used.

With lights switched on and non-actuated
brakes, the power rating is reduced to 5 watts
by a pulse-width modulated signal via the
vehicle electrical system control unit J519.

Thus a self-diagnosis/driver information
system (FIS) is possible for the second rear
light.
A defective brake light would be indicated in
FIS.

Brake not actuated

In vehicles with the "highline" version, national
lighting regulations can be adapted via
coding.

Rear lights on:

Brake actuated

Measuring equipment
DSO

5 V/Div.= 10 ms/Div.

Position

T

Time/Div.

Skip

Recorder operation

Print

Help

Photo

Channel A

Channel B

Trigger mode

Measuring
mode

Cursor 1

0

Cursor 2

Multimeter

SSP254_080

For non-plausible condition of the rotary
light control, the side lights and low beam
are switched on automatically by the vehi­cle electrical system control unit in the
"highline" version.

Electrical fault finding

In certain lighting circuits, an open-circuit
voltage measurement using the Multimeter is
not possible, as the semi-conductor elements
are clocked until the circuit is again closed.

For defective bulbs which are operated via the
vehicle electrical system control unit J519, no
permanent fault storage is effected, but only
for the period of the fault.
This means that the fault memory must not
be erased after changing a defective bulb.

Reversing lamp on:

Measuring equipment
DSO

5 V/Div.= 2 s/Div.

1

2

Position Time/Div.

3

self-diagnosis

1 - bulb illuminates
2 - bulb failure
3 - clock frequency of power output

Recorder operation

Photo

Channel A

Channel B

Measuring
mode

Cursor 1

Cursor 2

0

Multimeter

HelpPrintVehic le

SSP254_052

54

Turn signal/hazard warning light control

The functions:

– Anti-theft alarm flasher
– Central locking system flasher when

opening/closing
– Key-learn flasher for key adaption
– Crash flasher
– Panic flasher (USA only)

are specified by the central convenience elec­tronics and transmitted via the convenience
data bus to the vehicle electrical system con­trol unit, which then executes the "com­mands".

The hazard warning flasher signal is control­led separately by the vehicle electrical system
control unit, via the hazard warning flasher
button.
If, during hazard warning flashing, the turn
signal flasher is actuated, e.g. during towing,
the hazard warning lights lose their priority
for this period.

The turn signal clicking is generated by an
integral acoustic relay in the dash panel
insert.

For active hazard warning flasher with
ignition OFF, the flasher bulbs are actu­ated for a shorter period in order to mini­mise current consumption.

Turn signal light, right

Turn signal light, left

The signal for turn signal flashing or motor­way flashing is output via the steering column
switch module and executed by the vehicle
electrical system control unit.

Turn signal light, right

Turn signal light, left

SSP254_077

Motorway flashing is detected by the vehicle
electrical system control unit when the turn
signal lever is pressed and this triggers a tri­ple turn signal flash.

SSP254_078

55

Electrical system

Wash/wipe system

The wash/wipe system is equipped with the

speed-dependent 4-stage interval system.

A new feature is the re-wipe function for the

windscreen washer system.

Re-wiping occurs automatically 5 seconds

after the wash procedure is completed.

Reservoir in engine
compartment

The windscreen wash/wipe relays are inte­grated into the vehicle electrical system
control unit J519.

The washer fluid reservoir is a two-part
design for easier removal and installation.
An additional sensor is fitted for vehicles with
headlight washer system (HWS). In the
"highline" version, this is also used for the
Check system.
The purpose of the sensor, is to switch off the
HWS pump via the vehicle electrical system
control unit.
This prevents the pump running dry.

Reservoir in front left
wheel housing

Windscreen and
rear screen washer
pump V58

Connected

Headlight washer sys­tem pump V11

Windscreen washer fluid
level sender G33

SSP254_024

56

Control unit for trailer recognition J345

A separate control unit is required for trailer
operation. This transmits the vehicle lighting
system convenience CAN messages from the
vehicle electrical system control unit to the
trailer lights. A parallel link from the trailer
socket to the vehicle wiring would result in
fault detection via the microprocessor in the
vehicle electrical system control unit.

The diagnostic function of the control unit for
trailer recognition is performed via the
vehicle electrical system control unit J519,
address word 09.

Address word 09 - vehicle electrical system/

Central convenience
electronics

Communication takes place by means of the
convenience data bus via the central conven­ience electronics, as no separate K-wire
leads to the vehicle electrical system control
unit. For this reason, intact central conven­ience electronics are essential for perform­ing self-diagnosis.

SSP254_016

In the case of faulty communication
between the control unit for trailer recog­nition and the vehicle electrical system
control unit, the rear lights are actuated
as a warning signal.

Vehicle self-diagnosis

02 - Interrogate fault memory
03 - Final control diagnosis
04 - Basic setting
05 - Erase fault memory
06 - End output
07 - Encoding control unit
08 - Read measured value block
09 - Read individual measured value
10 - Adaption
11 - Log-in procedure

VAS 5051

SSP254_018

09 – Electronic central electrics
8E0907279B
int. load module RDW 0811
Code 101
Dealership No. 6803

Measuring

equipment

Skip Print

Help

Central convenience
electronics J393

K wire

CAN
BUS

J386

J388

Control unit for vehicle
electrical system J519

Control unit for trailer
recognition J345

Steering column
switch module J527

J387

Door control units

J389

Steering wheel
electronics

R

T

module J453

Electrical system

Convenience system

The convenience system previously used in

the Audi A2 is also used in the Audi A4.

In the series version, the following additional

functions

– Door warning lights

– Radio remote control

and in the optional version, the following

functions

– Anti-theft alarm with interior monitor and

towing protection (new)
– Electric sliding/tilting/glass sun roof
– Footwell lights
– Exit lights
– Mirror fold-in function
– Mirror memory function

are included in the Audi A4.

Central convenience unit J393

In the basic version without rear electric win­dow lifters, central locking control of the rear
doors is assumed by the central convenience
electronics.

Door control,
driver’s side unit
J386

Door control unit,
rear left J388
(optional)

58

Door control unit,
passenger’s side J387

Door control unit,
rear right J389
(optional)

SSP254_132

Central convenience electronics (CCE)

The following information and functions
are processed in the central convenience
electronics:

Sensors Actuators

Crash signal

(from airbag control unit J234)

Handbrake switch F9

Tailgate release

– Button for release, tailgate lock

cylinder F248
– 3. Remote control button
– Switch for tailgate to F206
– Switch for central locking, tail-

gate F218

Anti-theft alarm (optional)

– Contact switch for bonnet F266
– Ultrasonic sensor for anti-theft

alarm G209

Aerial for remote control,
Central locking and anti-theft
alarm in multi-communication bar

Reversing lamp M17

When mechanical window lifters
fitted in rear

– Door contact signal
– Locking signal
– Safe signal
for rear doors

Fuel filler flap

– Motor for tank cap locking V155

Tailgate

– Motor for tailgate release V139

Anti-theft alarm (optional)

– Horn for anti-theft alarm H8

(sounder)

– Turn signal lights via data bus to

vehicle electrical system con­trol unit J519

Interior light control

– Dimming of interior lighting
– Footwell light switching

(optional)

– Luggage compartment lamp

switching

Automatic closing/opening

– Window lifters via door control

units

– Sun roof

When mechanical window lifters
fitted in rear

– Lock rear door lock motors
– Safe rear door lock motors
– Activation of rear entry lights

(optional)

– Activation of rear door warning

lights

Enabling of door control units and
sunroof

Gateway function for diagnosis

– Control unit for vehicle electrical

system J519

– Steering column switch module

J527

59

Electrical system

Door control units

The door control units integrated in the
window lifter motors process the following
signals:

Sensors Actuators

Window lifter switches

Enabling via the CCE

Door lock feedback signal

– Door contact signal
– Locked signal
– Safe signal

for driver’s door also

– Lock cylinder switch unlocking/

locking F241

– Interior central locking switch

F59

– Switch for childproof lock E254

(optional)
– Central window lifter operation
– Mirror adjustment switching E48
– Switch for mirror adjustment E43
– Switch for mirror fold-in function

(optional) E263
– Switch for unlocking luggage

compartment (USA) E164
– Switch for seat memory, driver’s

side (optional) E263
– Switch for interior monitor E183

(optional)
– Inclination sensor switch

(optional)

for front doors also

Door locking and unlocking

Safe activation and deactivation of
the doors

Activation of illumination in the
doors

– Entry lights (optional)
– Door opener illumination

(optional)
– Door warning lights
– Switch illumination

for front doors also

– Electric mirror adjustment
– Mirror heating
– Mirror fold-in function
– Mirror memory

for driver’s door also

– Control of indicator LED
– Inclination sensor LED switched

off (optional)
– LED, interior monitoring
– LED, childproof lock

additionally for passenger's door

– Mirror for reversing (optional)

60

– Mirror release switch (optional)
– Sender for mirror position for

mirror memory (optional)

Mirror functions

The mirror heating is switched on together
with the

– rear window heating
– at an outside temperature of below 20 °C

switches on automatically.

When the mirror heating is switched on, the
heating capacity is 100%. Then the heating is
activated intermittently in accordance with
the ambient temperature and vehicle speed.
The mirror glass is kept at a temperature of
around 20 °C.

SSP254_126

The mirror fold-in function (optional) returns
the mirrors to the normal position at a vehicle
speed of 15 km/h. The function is disabled at
the same time.

Passenger’s side mirror

Lowering of the mirror (optional) takes place
when the reverse gear is engaged.

The mirror is returned to its original position
by

– operating the mirror selector switch, or
– when the speed of 15 km/h is exceeded.

SSP254_127

SSP254_128

Diagnostics

The adjustment of various settings can be
performed via the control unit coding and
adaption functions of the convenience
system diagnosis.

Customer requirements relating to the
convenience opening and closing functions
can be taken into account via adaption
channel 62.

In order to account for the resistance of
normal or insulating windows with regard to
the excess force limitation function of the
electric window lifters, the relevant type of
glazing is set in adaption channel 63.

61

Electrical system

Anti-theft alarm with interior monitor

Door lock

TS

The Audi A4 convenience system is available
with

– Anti-theft alarm
– Ultrasonic interior monitor
– Shattered glass sensor (Avant)
– Towing protection

as optional extras.

Ignition steering
lock D

Convenience data bus

Central control unit for con­venience system J393

High and low pitched tones

- air horn (sounder)

SSP254_133

Deactivation is performed by

– opening the vehicle via the radio remote

control or

– opening the vehicle via the driver’s door

lock cylinder and switching on the ignition
within 15 seconds. If this time period is not
observed or if the key used is not stored in
the immobiliser, the alarm is triggered.

The anti-theft alarm is only activated when
the vehicle is locked via the radio remote con­trol and by closing the driver's door.

62

Data exchange between the immobiliser in
the dash panel insert and the central conven­ience electronics takes place via the conven­ience data bus.

An innovation in the anti-theft alarm is that a
sounder with an integrated battery is fitted in
place of the horn.

This enables the alarm to sound even when
the power supply has been interrupted.

SSP254_134

The ultrasonic interior monitor and the tow­ing protection can be switched off from
inside the passenger compartment by means
of a switch.

Diagnostics

The angles of the both the longitudinal and
transversal inclination of the inclination sen­sor are displayed in the measured value
block.

SSP254_135

63

Electrical system

Functional mechanism of inclination sender

Towing protection is achieved by means of
the inclination sender installed in the central
convenience electronics.

The functional mechanism of the inclination
sender is based on the determination of
resistance changes relating to the volumetric
fluctuation of a viscous electrically conduc­tive fluid.

Variously arranged electrodes project into
this fluid.
Alternating fields are applied to the elec­trodes of the sender, which is divided into
sub-compartments.
When a change in position occurs, the distri­bution of the fluid in the chambers also
changes.
As the level of the liquid in the sub-compart­ments changes, the resistance determined for
the sub-compartments via the electrodes also
changes.

Indicator
fluid

Electrode
connections

The resistance is stored at the moment of
activation of the anti-theft alarm.
Changes in the position of the inclination
sensor caused by one-sided lifting of the
vehicle alter the resistance. The alarm is trig­gered.
The angle of inclination can be displayed in
the measured value blocks.

SSP254_110

Ceramic
housing

Sub-com­partment

Electrodes

Operational
amplifier

64

SSP254_111

Radio chorus II, concert II and symphony II

AKT

AL AUDIO

In the new Audi A4, the new generation of
radios, chorus II, concert II and symphony II
are available as options.

The following functions have been optimised:

– AM has been extended to include long

wave.

– There are now 12 programmable stations

for AM and FM.

All three radio versions are compatible with
the external CD changer (optional).

The optional CD changer is now built into the
glove compartment.

The BOSE sound system can be ordered as an
optional extra for all radio systems of the new
generation.

The connection of the new generation of
radios to the data bus information system
enables the exchange of large volumes of
data with other systems.

This makes new functions such as e.g.
convenience radio coding possible.

OFF

AIRBAG

LOAD

COMPAKT

Audi cd charger

ON

DIGITAL AUDIO

SSP254_106

Thanks to the convenience radio coding, man­ual deactivation of the radio anti-theft lock
following a loss of the power supply is no
longer necessary.
A prerequisite is that the radio is built into the
same vehicle.

Sound quality is enhanced by the installation
of a central loudspeaker in the centre of the
dash panel as well as a sub-bass speaker
under the rear shelf.

65

M

Electrical system

Radio chorus II

New functions with respect to the predeces­sor model include:

– Skip title function
– Scan function
– Dolby noise suppression

in the cassette player as well as

– a sorting function within a radio station

family

in the convenience radio tuner search func­tion.

SSP254_009

Radio concert II

A single speed CD player is integrated in the
concert II radio.

The cassette player has been discontinued.

Radio concert II and symphony II

The improved radio traffic news memory in
the Radio concert II and symphony II allows
the driver to program the time for starting the
two-hour recording of traffic news announce­ments. Two timers are available, which can be
programmed individually.

Example:

The driver can set the starting time for the
recording of radio traffic news announce­ments for the drive to work in the morning
and for the drive back in the evening sepa­rately.

SSP254_007

In order to improve sound quality, acoustic
curves related to vehicle type are stored in the
concert II and symphony II radios.

The acoustic curves are set in the control unit
coding function of the radio systems.

In addition, the sound settings for the FM, AM
and CD modes are stored separately in the
concert II and symphony II radios. Conse­quently, the various level controls do not
require resetting each time the driver
changes modes.

Radio reception is improved in the concert II
and symphony II radios by the use of the

ulti C ommunication B ar (MCB) with inte-

grated aerial diversity.

For further information on the aerial module,
please refer to 72.

66

Radio symphony II

A 6x CD changer as well as a cassette player
are integrated in the symphony II radio.

Searching for alternative frequencies is
speeded up by the use of a second tuner. The
second tuner also allows for Traffic Message
Channel (TMC) evaluation in the background.

For further information, please refer to the
relevant operating instructions.

SSP254_006

CAN networking in the new generation of
radios

All three radio versions are connected to the
data bus information system.

Important signals via the data bus informa­tion system:

Inputs/source

– Ignition on/steering column-

electronics

– Ignition key inserted/steering

column electronics

– Switch illumination/dash panel

insert

– Display illumination/dash panel

insert
– Speed/dash panel insert
– Convenience coding/dash panel

insert
– Vehicle identification/dash

panel insert
– Prompt signal/data bus informa-

tion
– Data bus system information/

dash panel insert
– Time/dash panel insert
– Control signals from multi-func-

tion steering wheel/steering

column electronics

Outputs/receiver

– Display functions/dash panel

insert

– Sleep signal/data bus informa-

tion

– TMC data for symphony II/

navigation system

– Convenience coding request/

dash panel insert

67

Electrical system

Example:

If the radio is switched on with the ignition
key (S-contact) this requires the exchange of
data between three control units:

– Steering column electronics,
– dash panel insert (gateway) and
– radio.

If the radio does not switch on,

– the signal input in the steering column

electronics (terminal 86S),

– communication between the steering col-

umn electronics and the dash panel
(convenience data bus) and

– communication between the dash panel

and the radio
(data bus information system)

must be checked.

Diagnostics

For diagnosis of radio systems concert II and
symphony II, current consumption of aerial
diversity is monitored via the intermittent
frequency (IF) wiring.

Test mode

The new radio versions are equipped with a
test mode.

Activating field intensity measurement:

– Radio switched off
– Hold down key 1
– Switch on radio

Activating GALA display volume increase:

For further information on IF wiring,
please refer to SSP 213, Page 54.

FM 1 DOT + 88.9

34300033 TP AF

SSP254_119

Button 1

Field intensity ­mean value

– Radio switched off
– Hold down key 2
– Switch on radio

68

GALA 0dB

Button 2

Increase in dB

SSP254_120

Navigation IV and Navigation Plus-D

The new Navigation System IV and Navigation
System Plus-D are equipped with the dynamic
routing system.

The following traffic hold-ups are taken into
account during route planning:

– closed roads
– tailbacks and
– slow-moving traffic.

The system’s sources of information are the
traffic information from the radio stations via
the Travel Message Channel and from the
telematics

®

(optional) via the telephone

connection.

Once it is switched on, the navigation system
takes account of the traffic messages within a
radius of approx. 50 km around the vehicle.

If the route planning is activated, any hold­ups are taken into consideration.

New hold-ups which arise are immediately
accounted for in the routing and the driver is
re-routed.

Data transfer of the traffic data is by

SSP254_129

Selectivity area for traffic
messages, 50 km

major diversion

– Travel Message Channel data from the

radio

– Telephone data from the telematics control

unit J526

to the navigation system via the data bus
information system.

Tailback

SSP254_113

local diversion

69

.

Electrical system

Within the menu structure of the navigation
system, the driver is able to

– switch the dynamic routing on and off,
– select the source of traffic information,
– manually exclude route sections from the

route planning.

For further information, please refer to the
operating instructions.

TELE

Menu

Travel Message Channel (TMC)

The TMC is a component of the Radio Data
System (RDS), which is transmitted by the
radio stations.

The information in the TMC includes the loca­tion, type and duration of traffic hold-ups
reported by the police, automobile associa­tions and government authorities in a coded
form standard throughout Europe.

The TMC data is not currently transmitted by
all radio stations.
This requires the use of a second tuner in the
radio or in the interface of the Navigation
System Plus.

As only the symphony II radio is equipped
with a second tuner, the use of TMC data for
dynamic routing is only possible with this
version.

RETURN

NAV

1 Traffic information is available.
Source: Radio

Alternative route Traffic information

now automatic

for route section

for route from here

INFO

read

interrogate latest

Settings

Dynamic routing in conjunction with the
chorus II and concert II radios is only possible
by means of the traffic messages via tele­phone with telematics

Diagnostics

The navigation system diagnostics is interro­gated via the L-wire.

70

®

Tailback function Back with RETURN

SSP254_130

Interface for Navigation Plus (R94)

The interface of the Navigation System Plus
performs the following tasks:

– Exchange of data bus information -

Navigation System Plus internal data bus

– Transfer of TMC data to the Navigation

System Plus for dynamic route planning

In order to receive the TMC data, an interface
connects the aerial and radio.

SSP254_122

The following data is exchanged via the
interface:

Input from data bus
information/sender

Display request/instrument cluster

Traffic news/Telematics

Fault messages/card reader

Control signals/multi-function
steering wheel

Terminal 15/steering column
electronics

Output to data bus
information/receiver

Display/instrument cluster

Control signals data bus/data bus
information system

Vehicle data/card reader

71

Electrical system

Multi-communication bar (MCB)

The Audi A4 Saloon features the multi-com­munication bar in the top part of the rear win­dow for the first time.

The

– aerial module,
– aerial for navigation system (GPS),+
– and aerial for telephone (GSM)

are fitted in the MCB.

The

– aerial diversity,
– aerial amplifier for the four radio aerials

(FM1-4, AM),

– 4 aerial amplifiers for the TV aerials 1-4,
– aerial for radio remote control, central lock-

ing (RCL),

– and the aerial for the telestart function (TS)

of the auxiliary heating

are integrated in the aerial module.

The aerial conductor is located in the rear
window. The electrical connection between
the aerial amplifier and the conductor on the
rear window is made by means of spring
contacts.

Both the GPS and the GSM aerials are also
fitted in the top edge of the rear window, but
these are not connected by means of conduc­tors in the rear window.

Thanks to this compact arrangement, no
aerials are visible from outside.

GSM

GPS

Aerial module

TS

Normal glazing

TS

SSP254_109

The emergency aerial for the telematics is
located at the rear bumper.

72

Insulating glazing

SSP254_013

Television (TV) tuner

The image and sound quality of each individ­ual tuner is monitored in the TV tuner. The
tuner with the best reception is switched
through to the operating unit.

Thanks to the high speed, switching can be
performed within a single scanning line.

The control signals of the Navigation Plus ­operating unit are transmitted via the data
bus system of the navigation system.

Transfer of the image and sound data takes
place via the conventional wiring.

The TV tuner is not connected to the data bus
information system.

Self-diagnosis

Address word 57

The video standard for the relevant country
can be set via the coding function.

The TV aerials can be activated for reception
consecutively in the final control diagnosis,
enabling the detection of a faulty aerial.

The condition of the connections to the
aerials, navigation system and external video
inputs can be displayed via the measured
value blocks.

SSP254_137

73

Electrical system

The electronic logbook, Audi Logbook

The Audi Logbook is a fully automatic logbook
which allows the customer to calculate
business and private journeys in order to
determine costs, e.g. for tax purposes.

The Audi Logbook is only available in
conjunction with Navigation Plus or
Navigation IV.

SSP254_065

CAN bus information

+ -

The Audi Logbook System includes:

– Chip card reader R99,
– PC card reader,
– Software CD for installing the Audi

Logbook program on the PC,

– Chip card.

For initial operation of the Audi Logbook, the
chip card must be activated using a PC and
PC card reader (see Owner's manual).

74

SSP254_040

In the ”business journey” mode, data relating
to

– date
– time at start of journey
– position at start of journey
– position at end of journey
– time at end of journey
– kilometres driven

are stored in the Chip card reader R99.

The date and route driven are stored In the
”private journey” mode.

The ”continue journey” mode is used to pre­vent short breaks from being stored (e.g. refu­elling stops).

Operation and setting of the Audi Logbook is
via the navigation system menu.

The following options can be selected:

– Business journey
– Private journey
– Continue journey

Around 250 individual journeys can be stored
on the chip card.
Once 200 individual journeys have been
stored in the card reader, the driver is
requested by a message on the navigation
system display to store the data on the chip
card.

The card reader has the capability to store
around 2700 individual journeys.

Select purpose of journey:

Back

Business journey

Private journey

Continue, business

Continue, private

Memory occupancy 0 %

LOGBOOK Back with RETURN

SSP254_131

The Audi Logbook has no diagnostic
capability.

Fault messages are indicated via the naviga­tion system display.
The messages displayed are generated in the
chip card reader and communicated to the
navigation system as information via the data
bus.

In order to activate the Audi Logbook,
adaption of the navigation unit must be
performed. (see workshop manual).

75

Heater/AC

Design and function

The air conditioner represents a further devel­opment of the two-zone air conditioning
concept previously used in the A6.

Operating and display unit E87.

The redesigned system is based on the
performance data for top of the medium
range vehicles, taking account of low system
weight and energy consumption as well as, to
an increasing extent, recycling capability.

Innovations include:

– Individual temperature control for both

driver and front passenger

– Option of synchronising the temperature

zones for driver and front passenger by
pressing the ”Auto” button for approx.
three seconds.

Example:
If the same temperature is desired for the
passenger’s side as for the driver’s side,
the ”Auto” button should be pressed for at
least three seconds.
The same applies the other way round, for
making the driver’s side temperature the
same as that of the passenger’s side.

– The fault diagnosis and measured value

blocks for the seat heating system are read
out via address word 08 for the air condi­tioner.

– The system is encoded automatically via

the dash panel insert.

SSP254_032

– Integrated rotary control knob with poten-

tiometer for seat heating.
(this means the potentiometers cannot be
replaced individually)

– Intake blower V42 for passenger compart-

ment temperature sensor G56 is integrated
and cannot be replaced individually.

A distinction is made between eight different
versions, identified by means of the part
number index:

– with or without seat heating
– with or without navigation system,
– at a later date, with or without air quality

sensor.

The operating and display unit E87 is
connected to the convenience CAN bus.
Diagnosis takes place via the K-wire.

76

7-piston compressor

Two versions of externally controlled com­pressors are used in the Audi A4:

– the 6-piston compressor, which you have

already studied in detail in SSP 240,

– the 7-piston compressor, which differs in

the number of pistons and the resulting
increased displacement.

Depending on the country-specific vehicle
version, the 7-piston compressor with its
higher total output is used (e.g. in hot coun­tries).

Based on the engine version installed, a dis­tinction is made between the following com­pressor
types:

– 6 and 7 pistons for compressor fitted on

right side of engine,

– 6 and 7 pistons for compressor fitted on

left side of engine,

– 6 pistons for 6-cylinder TDI Diesel mechani-

cal units.

SSP254_033

Distinguishing features to identify the com­pressor fitted are:

– Lettering on the compressor identification

plate is 6SEU for the 6-cylinder or 7SEU for
the 7-cylinder compressor.

– the greater outer diameter of the

7-cylinder compressor (approx. 122 mm)
compared to the smaller outer diameter of
the 6-cylinder compressor
(approx. 113 mm)

Vehicles equipped with a 7-piston
compressor, are fitted with a radiator fan
which has a higher output.

77

Heater/AC

Air conditioner

Flaps for
centre vent

Defrost
flaps

Defrost flap control
motor V107

Central flap
control motor V70

Temperature
sensor - fresh air
intake channel G89

Temperature
flap (upper)

Left temperature
flap control
motor V158

Temperature
flap (lower)

Right tempera­ture flap control
motor V159

Sender for outlet
temperature,
evaporator G263

Fresh air/air­flow flap

Recircula­ted-air flap

Air recirculation
flap control
motor V113

Motor for air flow
flap V71

Flaps for footwell
vent

Footwell vent tempera­ture sender (left) G261

Vent temperature
sender
left right
G150 G151

Footwell vent tempera­ture sender (right) G262

SSP254_019

78

The basic functions of the air conditioner in
the Audi A4 are based on the Audi A6 system
and includes the following features:

– Air-side separation for driver’s and passen-

ger’s side.

– The heat exchanger can be replaced with-

out removing the air conditioner.

– The PTC additional heater element for die-

sel mechanical units can also be replaced
without removing the unit.

– All control motors and potentiometers are

easily accessible and replaceable.

– Connecting hose from air conditioner to

glove compartment for supplying the glove
compartment cooler (optional).
(in vehicles without glove compartment
cooling, the connection is sealed with a
rubber plug).

– Modified fresh air blower for passenger

compartment (description, see section:
Fresh air blower/electronically controlled
fresh air blower, on page 81).

Rotary valve

SSP254_015

Connecting hose to glove
compartment cooler

Glove compartment cooling

The cooler fills the entire space of the glove
compartment. It can, for instance, hold two
bottles with a volume of 0.25 and 0.7 litres.
The cold air supply is achieved via a connect­ing hose from the air conditioner unit.
The hose is fitted with a rotary slide for cold
air regulation.

Two examples give an impression of its per­formance:

– Cooling of the cooler contents from

approx. +30 °C to approx. +16 °C within one
hour and

– after switching off the cold air supply,

warming up by approx. +4 °C per hour at an
ambient temperature of approx.
+30 seconds and exposure to the sun.

SSP254_034

79

Heater/AC

Solar roof

Solar generator

Air conditioner
with control
system

Contacts

For the first time, the A4 can optionally be
equipped with the solar roof previously used
in the A8 and A6.
The fresh air blower is continually driven by
electricity obtained from solar radiation.
The output is proportional to the intensity of
the sunlight.

Modifications to the familiar models:

– Re-engineered fresh air blower
– The DC/DC transformer has been discontin-

ued, its function is now performed by the
fresh air blower control unit J126.

Ventilation

SSP254_035

Significant advantages in comparison with
vehicles without solar roof are:

– lowered temperature level in vehicles

parked in the sun (see chart),

– increased efficiency of the air conditioner

as the interior temperature set is achieved
more quickly,

– despite the reduced output of the system

during the winter, an air-drying effect
occurs which effectively dehumidifies the
vehicle, reducing fogging of the windows.

80

Temperature [°C]

Time [min]

Heating without solar

Heating with solar

Global radiation

]

2

Radiation [W/m

SSP254_036

Fresh air blower

Control technology has been integrated in the
new fresh air blower.

It includes the following features:

– Integrated control unit with diagnostic

capability via the operating and display
unit E87 (fault memory and measured
value block diagnosis-capable control

unit),
– optimised bearings for smoother running,
– separate solar input.

The required blower speed is calculated in the
operating and display unit E87, and requested
by the control unit for fresh air blower J126
via a PWM signal.

In the case of malfunctions, such as e.g. a stiff
or blocked blower, this is signalled to the
operating and display unit E87 by duty cycle
changes based on the altered frequency. The
relevant fault is set.

The blower bearings have been re-engineered
in order to optimise the effectiveness of the
system.
This particularly benefits solar operation.

The energy supplied by the solar roof is
utilised to drive the fresh air blower by means
of special electronics via the separate solar
input in the blower.

SSP254_037

81

Heater/AC

Actuators/sensors

Ambient temperature sensor
G17

Dash panel temperature
sensor G56
and
Temperature selection in the air condi­tioner operating and display unit E87

Sender for footwell vent temperature,
right, G262

N

O

C

E

F

F

O

Sender for footwell vent tempera­ture, left, G261

Vent temperature sender, right, G151

Vent temperature sender, left, G150

Fresh air intake temperature
sensor G89

Evaporator outlet temperature
sender G263

82

High-pressure sender G65

Sunlight penetration photo­sensor G107

Signals:
Terminal 31b from automatic wash/wipe interval system
Regulating valve for air conditioner compressor N280
Air quality sensor G238

Automatic gearbox
control unit J217

9:36

28.07.2000

153.9

km

5244

Diagnosis interface for data bus
J533 (gateway)

Motronic control unit J220

Control unit with display in dash
panel insert J285

Control unit
for air conditioner

Diagnosis connection

Radiator fan control unit J293

Radiator fan V7

Regulating valve for air con­ditioner compressor N280

Central flap control motor V70 and
potentiometer G112

Defrost flap control motor V107 with
potentiometer G135

Motor for air flow flap V71 with
potentiometer G113

Temperature flap positioning motor V158
(right) with potentiometer G221

SSP254_041

Air recirculation flap control motor V113
for potentiometer G143

Temperature flap control motor V158
(left) with potentiometer G220

Series resistor for fresh air blower N24,
control unit for fresh air blower J126 with
fresh air blower V2

Signals:
ECON signal
Engine speed increase
Air conditioner compressor

83

Heater/AC

Functional diagram

for fully automatic air

conditioner

Components

C20 Solar cells

E87 Operating and display unit for

air conditioner
G59 Driver’s seat temperature sensor
G60 Front passenger’s seat temperature

sensor
G65 High-pressure sender
G89 Temperature sensor - fresh air intake-

channel
G107 Sunlight penetration photosensor
G112 Potentiometer in positioning motor

for central flap
G113 Potentiometer in positioning motor

for air flow flap
G135 Potentiometer in central flap control

motor defrost flap
G143 Potentiometer in central flap control

motor recirculated-air flap
G150 Vent temperature sender, left
G151 Vent temperature sender, right
G220 Potentiometer, positioning motor for

temperature flap, left
G221 Potentiometer, positioning motor for

temperature flap, right
G238 Air quality sensor
G262 Vent temperature sender, footwell,

left
G262 Vent temperature sender, footwell,

right
G263 Vent temperature sender, evaporator
J9 Relay for heated windscreen and

rear window
J126 Blower control unit
N280 Regulating valve for compressor,

air conditioner
S Fuses
V2 Fresh air blower
V70 Central flap control motor
V71 Air flow flap control motor
V107 Defrost flap control motor
V113 Air recirculation flap control motor
V158 Temperature flap positioning motor,

left
V159 Temperature flap positioning motor,

right

Z1 Heated rear window
Z6 Heated driver’s seat
Z8 Heated front passenger’s seat

Colour coding

= Input signal

= Output signal

= Positive power supply

= Earth

= CAN-BUS

Auxiliary signals

CAN-high convenience

1

CAN-low convenience

2

Terminal 75

3

Windscreen heating Z2

4

K-diagnostic connection

CAN-H CONVENIENCE

CAN-L CONVENIENCE

{

Connection to
convenience data
bus

84

15

30

J9

N280

S6
5A

G238 G65 V2/J126

Z1

Z6 Z8

M

C20

E87

S25
30A

S1
5A

S26
30A

S44
30A

G107

G59 G150G60 G151

t° t° t° t°

31

G112 G113

M M

G135 G143

M

M

V113V107V71V70

G220 G221

M

M

V159V158

t° t° t° t°

G263G262G261G89

in out

21

43

31

Heater/AC

Additional heater

Control and heater
unit for heating
system J162

Heating system
heat exchanger

+-

K

Fuel pump

Combus­tion air

Fan
drive

Flame sensor

Fuel tank

Glow plug

Combustion chamber

Exhaust
gas

Diffuser

SSP254_023

The Audi A4 can optionally be equipped with
an additional heater for coolant.
Its mode of operation corresponds to the
systems in use previously.
The additional heater warms the heating­system heat exchanger in the air conditioner
unit via the cooling-water circuit.

The cut-in time is ”programmed” via the dash
panel insert.

86

SSP254_097

87

254

All rights reserved, including the
right to make technical changes.

AUDI AG
Dept. I/VK-5
D-85045 Ingolstadt
Fax [phone]

040.2810.73.00
Technical status 10/00
Printed in Germany