2003 AUDI A8 Audi a3 8p

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Media Oriented Systems Transport
R
The name of this data bus system is derived
from "Media Oriented Systems Transport
(MOST) Cooperation". This is an association
formed by various motor vehicle
manufacturers, their suppliers and software
companies with a view to developing
a standard high-speed data transfer system. MOST bus
The term "Media Oriented Systems Transport"
signifies a network featuring media-oriented
data transport. This means that, in contrast to
the CAN data bus, address-oriented
messages are transmitted to a specific
receiver.
This technique is used in Audi vehicles for the
transfer of infotainment system data.
The infotainment system offers a wide range
of modern information and entertainment
media. In addition to the familiar CAN bus
systems, use has been made for the first time
in the Audi A8 ´03 of an optical data bus
system.
SSP282_034
Design and operation of the MOST bus
are described in SSP 286 – New data bus
systems.
System manager
Sound system
DisplayOperating unit

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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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Electrical System
Both in the modern business world and in the
private domain, mobile information and
entertainment are becoming ever more
important. In other words, vehicle occupants are becoming
increasingly interested in enjoying the benefits of
modern media.
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Infotainment
DVD - Video
TV reception
Minidisc/CD audio Internet
EmailTelephone
Telematics DAB - Digital radio
CD/DVD navigation Central display
and control

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SSP282_096
TP TMC
Tr. 12
10:56
D2 Private
With this in mind, the Audi A8 ´03 is fitted with
an infotainment system offering a wide range
of modern media.
Design and operation are described in
SSP 293 - Audi A8 ´03 Infotainment.
Memory SourceCD 1
Manual SoundDire Straits - Brothers in …
Forward

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Electrical System
The headlight in the Audi A8 ´03 combines both
design elements and innovative technology.
Headlight versions:
– Basic halogen version H7
Dynamic headlight range control is not
necessary with halogen headlights. The air
suspension provides compensation for static
load statuses and a thumbwheel is therefore
also not required.
– Bi-xenon version
– Bi-xenon version with integrated adaptive
light function
The headlight range control unit J431 is
responsible for providing static and dynamic
compensation for vehicle tilting as well as
actuation of the static adaptive light
function. The sensor signals of the 4-level air
suspension system are picked off by the
drive system CAN for control purposes. A
distinction is made between the two
gas-discharge lamp versions by way of
appropriate encoding (1 or 2) at the
headlight range control unit.
Lighting system
Front lights
SSP282_056
HPV stands for high-performance bulbs,
which are extremely compact and have a far
longer service life. They have a 25 % lower
power input than conventional bulbs. Such
bulbs cannot be replaced by customers.
Both bi-xenon versions feature an ellipsoid
module with a moving screen to achieve both
dipped beam and main beam with xenon light.
The automatic dynamic headlight range control
represents a more advanced version of the
standard automatic control system. It provides
headlight tilt compensation not only for various
load statuses but also as a dynamic function
reacting to differences in running gear
inclination caused by acceleration and
deceleration.
Dipped beam/main beam
(Bi-Xenon/D2S - gas-discharge lamp)Turn signal indicator
(2 x 16 W HPV bulb - yellow) Parking light
(W5W/5 W bulb)Adaptive light
(H8/35 W bulb)
Additional main beam
Headlight flasher
(H7/55 W bulb)Reflector
for adaptive light

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Light functions
SSP282_087
Adaptive light
The additional reflector with a 35 W H8
halogen bulb is actuated as the situation
requires to ensure earlier perception of other
road users or obstacles.
When reversing or parking, both adaptive
lights are activated to provide the driver with a
better overall view of the surrounding area.
Adaptive light
Control of the headlight functions is a complex
process.
It involves real time evaluation of several
signals (e.g. vehicle speed, steering angle and
turn signal indicator) by the headlight range
control unit J431.
SSP282_092
The optional headlights with adaptive light
function are a clearly visible innovative feature
in the Audi A8 ´03. To implement this function,
the headlights are provided with an additional
reflector between dipped beam and main
beam.

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Electrical System
Side lights
This is the first Audi vehicle to be fitted with
LED-type lights. The individual LEDs are fitted
in a graduated arrangement under a
transparent glass lens and give off a yellow
light when switched on. They appear neutral in
colour when switched off.
LED technology offers numerous advantages:
– Rapid attainment of full power
– Up to 50 % energy saving as compared to
bulbs
– Service life equal to that of the vehicle
– Shallow design
– Bright, distinct marking effect makes
vehicle more noticeable
SSP282_088
Assistant lighting system
This system adapts the vehicle lighting to the
prevailing light conditions. For this purpose
the light switch must be set to AUTO. The rain
and light detector sensor G397 establishes
the prevailing light conditions and activates
the vehicle lighting system if appropriate.
Assistant lighting applies to:
– Dipped beam
– Parking lights
– Tail lights
– Number plate light
Operation of the assistant lighting system is
described in SSP 288 – Audi A8 ´03
Distributed Functions.
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