2003 AUDI A8 Audi a3 8p

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Passenger Protection
Up-front sensors
For the first time, use is made in the
Audi A8 ´03 of so-called up-front sensors.
SSP282_072
Lateral acceleration sensors
Further acceleration sensors are
located at the B and C-pillars.
SSP282_073
Detection of rear-end collision
Rear-end collisions are detected by way of a
sensor in the airbag control unit J234 and a
plausibility function involving the driver's and
front passenger's front airbag crash sensors
G283 and G284.
These take the form of two additional front-
end acceleration sensors on the right and left
beneath the corresponding headlight.
C-pillar sensor B-pillar sensor

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Active head restraints
The front seats of the Audi A8 ´03 are provided
with active head restraints.
With this system, the head restraints move
forwards in the event of a rear-end collision to
shorten the distance between head and
restraint.
SSP282_082
The danger of cervical vertebrae injury is
greatly diminished by reducing the relative
acceleration between shoulder and head.
In head-on collision situations, the mechanics
of centrifugal weight are neutralised.
Belt tensioners
Five belt tensioners are fitted as standard.
There is no centre belt tensioner if the rear
seats are electrically adjustable.

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Two different versions are available:
– 420 Nm for the V8 5V 4.2 l or
3.7 l engine and
– 600 Nm for the V8 TDI 4.0 l or
6.0 l W12 engine To satisfy high comfort requirements, the
Audi A8 ´03 features a new 6-speed automatic
gearbox capable of handling a high engine
torque of max. 600 Nm.
Gearbox
Design and operation of the 09E gearbox
are described in SSP 283 (Part 1) and
SSP 284 (Part 2).
SSP282_043
Technical data
Designation: 09E
Factory
designation: AL 600-6Q
ZF
designation: 6HP-26 A61
Type: 6-speed planetary
gearbox, featuring electro-
hydraulic control
with hydrodynamic
torque converter and
slip-controlled lock-
up clutch
Control: Via mechatronic system
(integration of hydraulic
control unit and
electronic control
to form one unit)Max. torque
transmission: 420 Nm for
V8 5V 4.2 l /3.7 l engine
600 Nm for
V8 TDI 4.0 l /W12
6.0 l engine
Front/rear axle
torque distribution: 50/50
Gear oil capacity
(total): 10.4 litres ATF
Gear oil capacity
(replacement): 10 litres ATF
Total weight: approx. 138 kg
(420 Nm version)
approx. 142 kg
(600 Nm version)

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Selector lever/button kinematics
To prevent inadvertent shifting into selector
lever position "S", a change has been made to
the selector lever kinematics such that
switching to "S" involves pressing the button
in the gearstick knob.
A small gear mechanism is provided in the
gearstick knob to reduce the required button
operating force.
The locking rod is actuated by the application
of pressure, which means changes have also
been made to kinematics and gearstick knob
assembly (refer to Workshop Manual).
In terms of the following functions, there are
interesting new aspects to the shift
mechanism in the new Audi A8 '03:
– Shift mechanism kinematics
– Ignition key removal lock
– Selector lever lock
– Selector lever lock emergency release
– Selector lever/lock button kinematics
Ignition key removal lock
Major modifications have been made to
operation of the ignition key removal lock and
selector lever lock (shiftlock). On account of
the new entry and start authorisation switch
E415, there is no mechanical link between the
shift mechanism and ignition lock (locking
cable).
Selector lever lock emergency release
This modification means that the selector lever
remains locked in position "P" in the event of
malfunctions or power supply failure
(e.g. battery flat).
Selector lever lock emergency release is
provided to enable the vehicle to be moved
(e.g. towed) in such situations.
Gearbox
SSP282_048 SSP282_049

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All axle components are new on account of
the geometric and kinematic modifications as
compared to the predecessor model, the air
suspension and the weight reductions
achieved.
Front axle
The familiar four-link front axle was retained
for the Audi A8 '03.
A significant new feature is the air
suspension in combination with
electronically controlled dampers (refer to
Section on air suspension).
Front axle highlights
– Subframe
– Auxiliary frame
– Anti-roll bar
– Wheel bearing housing
– Wheel bearing with wheel speed sensing
– Mounting bracket for damper unit
Front axle design and operation are
described in SSP 285.
SSP282_050
Running Gear

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All axle components are new on account of
the geometric and kinematic modifications as
compared to the predecessor model, the air
suspension and the weight reductions
achieved.
Rear axle highlights
– Use of air suspension in conjunction with
electronically controlled damping
– Aluminium subframe to help
reduce weight
– Connection of anti-roll bar to trapezium
link
– Use of shorter track rod to reduce change
in toe on compression and extension of
suspension
– Use of ball studs to connect wheel bearing
housing and track rod, thus reducing
secondary spring rate
– Use of slotted bonded rubber bushes in
upper transverse link and connection
between trapezium link and subframe
Rear axle design and operation are
described in SSP 285.
Rear axle
The rear axle is a more advanced version of
the familiar Audi A8 trapezium-link axle.
Running Gear
SSP282_051

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4-level air suspension
The introduction of the Audi A8 ´03 is
accompanied by a system featuring new
technical details and functions. The major
differences with respect to the familiar Audi
allroad quattro
® system are as follows:
EDC instead of PDC damping
The control system makes allowance for the
currently applicable driving status. Wheel
movement (unsprung masses) and body
movement (sprung masses) are detected.
Various damping characteristic curves are
implemented within the scope of three
selectable programs (modes) and each
damper can be controlled individually.
Control concept
Integration into the MMI makes for
convenient, logical and easy to remember
control action.
Extended range of sensors
Use is made of three acceleration sensors to
detect body movement.
External air springs
The air spring not only replaces the steel
spring, it also offers major advantages (refer
to SSP 242). The new external routing of the
air spring through an aluminium cylinder
permits the use of thinner-walled bellows.
This results in an even more sensitive
response to road surface irregularities.
SSP282_052
SSP282_053
Optimal comfort and road safety are thus
always guaranteed whichever mode is set
(comfort or sports).
The term "mode" thus describes a
coordinated combination of adaptive
suspension program and damping map.

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Bus topology
Electrical System
The increasing demand for additional
functions and convenience in the vehicle calls
for the use of ever more wide ranging
electronics.
The increased use of electronics also requires
a new approach to data transfer between the
individual control units. This also applies to
the Audi A8 ´03, in which more than 70 control
units have to communicate.
Distance regulation
control unit J428
Electric park and
handbrake control
unit J540Headlight range
control unit
J431Airbag control unit
J234ABS with EDL
control unit
J104
Engine control unit
J623Adaptive
suspension control
unit J197 Engine control
unit 2 J624Automatic gearbox
control unit
J217
Anti-theft/
tilt system control
unit J529
Boot lid control unit
J605Wiper motor control
unit J400Garage door
operation control
unit J530 Multifunction
steering wheel
E221
Convenenience
system central
control unit J393On-board power
supply control unit
J519
On-board power
supply control unit 2
J520Steering column
electronics control
unit J527Steering angle
sender G85
Driver side door
control unit J386Front passenger
side door
control unit J387Rear left door
control unit J388Rear right door
control unit J389Seat adjustment
control unit
J136Front passenger
seat adjustment
control unit J521 Control unit with
display in dash panel
insert J285
Diagnostic connection T16
Dash panel insert CAN
Drive system CAN
Diagnosis CAN
Convenience CAN
Internal bus link
LIN
Adaptive cruise control
CAN