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A further innovation is the display of the max-
imum and minimum engine oil levels in the
measured value block after the most recent
service operation.
The adaptation of the mileage/kilometre read-
ing after replacement of the dash panel
insert, is possible (several attempts) up to a
recorded distance of 5 km after installation. The dash panel insert checks the plausibility
– of both fuel gauge senders in quattro
vehicles
– as well as the terminal 15 input signal.
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.
Control unit with
display unit in
dash panel insert J285
Control unit for steering
column electronics J527
Ignition lock D Convenience data
bus
Terminal 15
Diagnostics
SSP254_138
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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:
– 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 multi-
function 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 electri-
cal system control unit J519.
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.
Cruise control
system E45
Ignition
steering lock Steering column
electronics J527
Turn signal
switch E2
SSP254_105
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Steering angle sender G85
The determination of steering angle is per-
formed via optical elements in the steering
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.
The steering column switch module
must always be coded.
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
data bus via the central convenience electron-
ics J393, as no separate K wire is connected
to the steering column electronics.. (see
graphic 254 018 on Page 57)
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".
Wiper
switch E
Steering angle
sensor G85
Steering column electronics
module J453 with operating
unit E221
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 elec-
tronics J527 via conventional wiring. The
switch positions of the ignition lock are pre-
pared by the electronics, supplied to the con-
venience CAN bus and then transmitted via
the gateway to the drive and infotainment
CAN bus systems.
Coil spring
RT
SSP254_014
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Auxiliary signals
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
13 Ignition lock terminal P
X
Y Connection within the functional
diagram
Z
Electrical system
Functional diagram
Steering column switch
module
(maximum equipment)
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
Colour coding
= Input signal
= Output signal
= Positive power supply
= Earth
= CAN-BUS
{
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5 V/Div.=10 ms/Div.
0 T
Electrical system
In the "highline" version of the vehicle electri-
cal 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.
In vehicles with the "highline" version, national
lighting regulations can be adapted via
coding.For non-plausible condition of the rotary
light control, the side lights and low beam
are switched on automatically by the vehi-
cle electrical system control unit in the
"highline" version.
SSP254_080
Measuring equipment
DSORecorder operation
Photo
Channel A
Channel B
Measuring
mode
Cursor 1
Cursor 2
Multimeter
Help Print
PositionTime/Div.
Trigger mode
Skip
Brake not actuatedBrake actuated
Rear lights on:
5 V/Div.=2 s/Div.
0
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.
Measuring equipment
DSORecorder operation
Photo
Channel A
Channel B
Measuring
mode
Cursor 1
Cursor 2
Multimeter
Help Print Ve h i c l e
self-diagnosis
Position Time/Div.
Reversing lamp on:
1 - bulb illuminates
2 - bulb failure
3 - clock frequency of power output
1
2
3
SSP254_052
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The hazard warning flasher signal is control-
led 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.
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 elec-
tronics and transmitted via the convenience
data bus to the vehicle electrical system con-
trol unit, which then executes the "com-
mands".
The signal for turn signal flashing or motor-
way flashing is output via the steering column
switch module and executed by the vehicle
electrical system control unit.
For active hazard warning flasher with
ignition OFF, the flasher bulbs are actu-
ated for a shorter period in order to mini-
mise current consumption.
Motorway flashing is detected by the vehicle
electrical system control unit when the turn
signal lever is pressed and this triggers a tri-
ple turn signal flash.
Turn signal light, right
Turn signal light, left
Turn signal light, right
Turn signal light, left
SSP254_077
SSP254_078
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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.
In the case of faulty communication
between the control unit for trailer recog-
nition and the vehicle electrical system
control unit, the rear lights are actuated
as a warning signal.
RT
Address word 09 - vehicle electrical system/
Central convenience
electronics
Communication takes place by means of the
convenience data bus via the central conven-
ience electronics, as no separate K-wire
leads to the vehicle electrical system control
unit. For this reason, intact central conven-
ience electronics are essential for perform-
ing self-diagnosis.
K wireCAN
BUS
Central convenience
electronics J393
SSP254_018J389
J388J387
J386
Door control units
Control unit for vehicle
electrical system J519
Control unit for trailer
recognition J345
09 – Electronic central electrics
8E0907279B
int. load module RDW 0811
Code 101
Dealership No. 6803
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
Measuring
equipmentSkip PrintHelp
Steering column
switch module J527
Vehicle self-diagnosis
Steering wheel
electronics
module J453
SSP254_016
VAS 5051
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In the basic version without rear electric win-
dow lifters, central locking control of the rear
doors is assumed by the central convenience
electronics.
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.
Electrical system
Central convenience unit J393
Door control unit,
passenger’s side J387 Door control,
driver’s side unit
J386
Door control unit,
rear right J389
(optional) Door control unit,
rear left J388
(optional)
SSP254_132