AUDI A8 2003 D3 / 2.G Technical Features Manual

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Automatically controlled
starting
The automatic start control is integrated into
the engine control unit.
A new feature is that starter control is no
longer implemented by way of the ignition/
starter switch D (switching of terminal 50),
but rather it is performed automatically by
the engine control unit.
Release for starter actuation is always
transmitted by the entry and start
authorisation control unit J518 to the engine
control unit J623.
In addition to general release by the
immobilizer, the following start release
conditions also have to be satisfied:
– Start signal from entry and start
authorisation switch E415 or entry and
start authorisation button E408
– Clutch pedal pressed, signal from clutch
pedal switch F194 (manual gearbox only)
– Selector lever position P or N (automatic
gearbox control unit J217)
– In the event of start signal via entry and
start authorisation button E408, brake
must be pressed (signal from brake light
switch F via separate interface)
As a safeguard, P/N signal or signal from
clutch pedal switch F194 must be applied
to the separate interfaces of the two
control units (J623 and J518).
Additional safeguard, as entry and start
authorisation button E408 can be
actuated by front passenger.
1
2 1
1
2

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Engine, Mechanics
Sequence of operations
1 Entry and start authorisation switch E415/entry and start authorisation button E408
2 Entry and start authorisation control unit J518
The entry and start authorisation control
unit checks for authorisation – in the form
of information on selector slide position N
or P – from the automatic gearbox control
unit J217 and for brake application in the
case of a start signal from the entry and
start authorisation button E408.
3 Engine control unit J623 Application of selector slide position P/N or
"clutch pressed" information to the engine
control unit (separate interface) causes the
two starter relays J53 and J695 to be
actuated simultaneously. The relays then
switch terminal 50 for starter actuation.
The starter operates and cranks the engine.
On exceeding a defined engine speed, the
engine control unit J623 recognises that
the engine has started and the relays are
deenergised (thus terminating starting
process).
As a safeguard, two relays are connected in
series. In the event of fusion welding of the
make contacts (relay remains closed
following deenergisation), the engine
control unit J623 can thus interrupt the
circuit (terminal 50) by way of the other
relay in each case.
The two relays are deenergised alternately
in order to ensure even make contact wear
(break spark) in both relays. The
deenergisation sequence alternates. The driver triggers a brief start signal
(min. 20 ms) by turning the ignition key to
start position or by pressing the entry and
start authorisation button E408.
If the start prerequisites have been
satisfied, the entry and start authorisation
control unit J518 transmits a start request
– terminal 50 ON – to the engine control
unit J623.
The entry and start authorisation control unit J518 also controls the terminal 15 and
terminal 75x circuits.
Relay operation is monitored and faults diagnosed by evaluating the alternating
deenergisation with the aid of the terminal
50R interface.
The terminal 50R interface represents a link
with terminal 50 and provides the engine
control unit J623 with feedback for start
control/diagnosis.
Automatically controlled starting is not
permitted in the event of undervoltage or a
system fault.
The engine can however be started
manually by way of corresponding start
signal actuation.
To relieve the load on the starter and
battery, the relay actuation time is
limited to approx. 10 seconds per starting
operation (automatic or manual starting).

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D1
30
15
J329J53J695J694
75xE415
N376
6x
J623
J518
50R
50R
3
12
12
E408
STOP START
58s
210 210
D1 Inhibitor reading unit
E408 Entry and start authorisation button
E415 Entry and start authorisation switch
J53 Starter motor relay
J329 Terminal 15 voltage supply relay
J518 Entry and start authorisation
control unit Block diagram
SSP282_024
Colour code
= Input signal
= Output signal
= Positive supply
= Earth
J623 Engine control unit
J694 Terminal 75x voltage supply relay
J695 Starter relay 2
N376 Ignition key withdrawal lock magnet
Additional signals
F - Brake light switch
Manual gearbox -> F194
Clutch pedal switch
Automatic gearbox -> Selector lever
position from automatic gearbox
control unit J217
Terminal 50/starter
1
2
3

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Engine, Mechanics
Explanatory notes on internal control unit
sequence chart
Request for starting (terminal 50 ON from
entry and start authorisation control unit
J518) energises the two relays. Locking-in
takes place during the initialisation phase of
engine control unit J623.After initialisation, the engine control unit
assumes further starter control tasks as described
under item 3.
SSP282_064
Starting Engine running
Ignition on
Term. 15
Start request from
driver authorisation system
Engine start recognition
(engine speed)
Relay deenergisation by engine control unit
Term. 50R/diagnosis
Engine control unit initialisation
Engine control unit active Start request retained manually
Start request briefly activated Engine speed increases
Relay deenergisation
Starter speed
Starter operation feedback signal
Locking-in Engine control unit active

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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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Highlights of automatic gearbox 09E
The 6-speed planetary gearbox is based on the
Lepelletier principle.
This concept is characterised by harmonic
gear ratio steps and the implementation of six
forward gears and one reverse gear with only
five selector elements.
Use is made in this gearbox of a new internal
gear oil pump featuring a lower delivery
volume and reduced leakage.
In addition, it was possible to achieve
optimisation of the oil supply with lower
leakage rates in the hydraulic control system.
The "stationary disconnection" function
reduces engine output when the vehicle is
stopped with a gear engaged by interrupting
power transmission.
A particularly noteworthy feature of the 09E
automatic gearbox is the relocation of the
front-axle differential (flange shaft) to in front
of the torque converter.
The distance between flange shaft and engine
flange is now only 61 mm (01L = 164 mm).
Gearbox
SSP282_044
SSP282_045
(AL 600-6Q)

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The mechatronic system integrated into the
gearbox housing is a new development,
combining the hydraulic control unit,
sensors, actuators and electronic gearbox
control unit in a coordinated assembly.
SSP282_046
All data exchange with the vehicle periphery
takes place via the drive system CAN, thus
reducing the number of vehicle periphery
interfaces to a minimum (11 pins) and at the
same time enhancing operational reliability.

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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