ESP AUDI A8 2003 D3 / 2.G Technical Features Manual (96 Pages)

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Seats
A new seat concept was developed for the
Audi A8 ´03.
The basic seat features the following
standard functions:
– Electric seat length, height and angle
adjustment
– Electric backrest angle adjustment
– Front crash-active head restraints (refer to
Page 21)
The basic seat can additionally be ﬁtted with
– Four-way lumbar support
– Seat memory for driver and front
passenger
– Electrically adjustable head restraints
– Electric belt height adjustersExtra features of sports and comfort seats:
– Electric top 1/3 backrest adjustment
– Electric seat depth adjustment
Optional extras for comfort seat:
– Climate function (refer to Page 85)
– and/or massage function
The massage function is implemented by way
of rhythmic action of the electromechanical
lumbar support, thus massaging and relaxing
the back muscles.
The ﬁxed rear seat bench versions correspond
to those of the front seats, with the third head
restraint being fully retractable. Electric
individual seats are however only available as
"Basic" and "Comfort" versions.
SSP282_116
Crash-active, electronic
head restraint with 70 mm height
adjustment
Thorax/pelvis
side airbag
Backrest fan
Seat cushion fan Electric seat depth adjustment – As the
structure moves forwards it pulls the
padding with it and so extends the seat
area by 50 mm. Backrest adjustment –
The angle of the top
1/3 of the
backrest can be adjusted by 15°
for enhanced shoulder comfort.
Lumbar support with massage
function over a length of 60 mm

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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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Hot-film air-mass meter G70
Engine speed sender G28
Hall sender G40 (bank 2) and
Hall sender 2 G163 (bank 1)
Lambda probe G39
(bank 1)
Lambda probe II G108
(bank 2)
Lambda probe after catalyst G130
(bank 1)
Lambda probe II after catalyst G131
(bank 2)
Throttle valve control
part J338 with
Throttle valve drive G186
(electric power control)
Throttle valve drive angle sender 1 G187
Throttle valve drive angle sender 2 G188
Coolant temperature sender G62
Knock sensor I G61 (bank 1) and
Knock sensor II G66 (bank 2)
Additional signals:
– Air conditioner requirement
– Cruise control switch
– Term. 50, stage 1
– Automatic gearbox selector lever positionEngine control unit J623
Steering
angle sender G85
ESP
control unit J104
Dash panel
insert CANAutomatic
gearbox
control unit J217
Airbag
control unit J234Intake manifold changeover valve
N156 and
Intake manifold changeover valve 2
N261
Left electrohydraulic engine mounting
solenoid valve N144 and
Right electrohydraulic engine mounting
solenoid valve N145
Torque rod valve N382
Lambda probe heater Z19
(bank 1) and
Lambda probe 2 heater Z28
(bank 2)
Lambda probe 1 heater
after catalyst Z29
Lambda probe 2 heater
after catalyst Z30
Additional signals:
– Starter relay term. 50, stage 2
– Tank leakage pump (USA only)
– Air conditioner compressor (out)Fuel pump relay J17
Fuel pump G6
Fuel pump II relay J49
Fuel pump G23
Injectors N30, N31, N32, N33 (bank 1)
Injectors N83, N84, N85, N86 (bank 2)
Ignition coils N (no. 1 cyl.), N128 (no. 2 cyl.),
N158 (no. 3 cyl.), N163 (no. 4 cyl.)
Ignition coils N164 (no. 5 cyl.), N189 (no. 6 cyl.),
N190 (no. 7 cyl.), N191 (no. 8 cyl.)
Activated charcoal filter system solenoid
valve 1 N80
Secondary-air pump relay J299 and
Secondary-air pump motor V101
Secondary air inlet valve N112
Throttle valve control part J338
With throttle valve drive G186
Inlet camshaft timing adjustment valve 1
N205 (bank 1)
and
N208 (bank 2) Pedal position sender/accelerator
pedal module with accelerator pedal
position sender G79 and accelerator
pedal position sender 2 G185
Brake light switch F and
Brake pedal switch F47
Clutch pedal switch F36
(manual gearbox only)
Control unit with display in dash
panel insert J285Data bus diagnostic
interface J533
Engine, Mechanics
System layout
Actuators/sensors
SSP282_091 Drive system CAN
Diagnosis CAN

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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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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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SSP282_061
Setting desired speed
The desired speed is the maximum speed to
be controlled by the ACC on an open road
(corresponds to cruise control system
function).
Pressing the SET button stores the current
speed as desired speed.
Running Gear
The set speed is displayed by a bright red LED
in the speedometer rim and the "ACC active"
symbol appears in the speedometer.
The "ACC active" status is indicated by faint red
illumination of all LEDs in the range between
30 and 200 km/h.
SSP282_060

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Setting desired distance
The desired distance from the vehicle in front
can be set by the driver in four stages. The
distance set by the ACC is governed by the
respective vehicle speed. The distance
increases with increasing vehicle speed.
The minimum setting ensures compliance
with the permissible safety distance when
travelling at a constant speed in trafﬁc.
The desired distance from the vehicle in front
is set by means of the sliding switch on the
stalk. Actuation of the switch increases or
reduces the distance by one stage each time.
The desired distance selected determines the
vehicle acceleration dynamics.
The chosen distance is brieﬂy indicated on
the info line in the speedometer centre
display.
The centre display is activated the ﬁrst time
the button is pressed.
The number of bars between the vehicles
displayed corresponds to the distance stage
selected in each case.
The distance stage can be set for each driver.
Design and operation of the ACC are
described in SSP 289 – Adaptive Cruise
Control.
Pay attention to operating instructions
and manuals.SSP282_062
SSP282_059

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Vehicle electrical system
A major factor in terms of vehicle reliability is
one which is never even seen: the electrical
system.
Use is made for the Audi A8 ´03 of a customer-
speciﬁc one-piece modular wiring harness.
"One-piece" means that power is supplied for
all essential electrical functions from a single
continuous wiring harness. The only isolating
points are at the doors, roof module and
engine.
"Customer-speciﬁc" means that each wiring
harness is designed to serve exactly the
equipment ordered by the customer. The
wiring harness is subdivided into individual
logic modules, each of which is responsible
for a clearly deﬁned range of functions.
SSP282_038
Design and operation of the optical ﬁbre
are described in SSP 286 – New data bus
systems. A plastic optical ﬁbre is ﬁtted for the
transmission of optical communication and
infotainment signals.
Its advantages as compared to a copper
conductor are its insusceptibility to
electromagnetic interference, a high
transmission capacity and less weight.
To achieve greater headroom, the wiring
harness to the roof module has been
extended to include the ﬂexible ﬂat cable
(FFC). This represents a new method of
solving the wiring problem in extremely
conﬁned spaces (max. 2 mm between
headliner and body outer skin).

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Electrical System
Convenience and security
electronics
"Advanced Key" entry and start
authorisation system
"Advanced Key" can be taken to mean an
"advanced locking and security system".
It takes the form of a non-contacting key
recognition system. With the "Advanced Key"
package, the "Vehicle unlocking" and "Vehicle
locking" functions by way of a mechanical or
remote control key are supplemented by the non-
contacting functions "Vehicle unlocking" and
"Vehicle locking".
Functions
Advanced Key "unlocking"
The key owner enters the key detection zone next
to the vehicle (less than 1.5 m from door handle)
and reaches into the recessed handle moulding.
aerial.
The key responds by way of radio waves and the
vehicle is unlocked if authorised.
Advanced Key "starting"
The driver presses the start button, which again
initiates a key scan via the passenger-
compartment aerials near the selector lever, at the
rear centre vents and at the rear centre armrest.
The remote control key provides conﬁrmation,
with the result that the ignition is switched on on
depressing the ﬁrst stage of the start button and
the engine started on depressing the second
stage. The engine is switched off with the STOP
button.
Advanced Key "locking"
If the vehicle is to be locked from the outside, it is
sufﬁcient to press the locking button in one of the
door handles. Actuation of the locking button
triggers a key scan via the door handle aerial and
the vehicle is locked on conﬁrmation of the remote
control key.In addition, the driver can start the engine
with the START/STOP button (START/STOP
function) without inserting the ignition key
in the electronic ignition lock.
SSP282_093
SSP282_094
SSP282_095
Design and operation are described in
SSP 287 – Audi A8 ´03 Electrical
Components.
A proximity sensor starts a key scan by way of an

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