2003 AUDI A8 ECO mode

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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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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.
SSP282_090
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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An optional feature for the Audi A8 ´03 is
4-zone climate control, enabling both driver
and all passengers to make individual
settings independently of the climate control
level selected for the other occupants.
Design and operation
The air conditioning system represents a
more advanced version of the concept
employed in the Audi A8 predecessor model
with 2-zone climate control and features fully
automatic regulation.
Heating/Air Conditioner
The following components are new features
as compared to the systems previously fitted
in the Audi A8:
– Humidity sender G355
– Evaporator outflow temperature sender
G263
– Two versions: 2-zone front climate control
with 12 control motors and 4-zone front
and rear climate control with 15 control
motors
– Rear climate control with electric rear
additional heater as additional equipment
("4-zone system") – rear left and rear right
footwell heater element Z42 and Z43
– Second control and display unit with
4-zone climate control, Climatronic control
unit J255, rear Climatronic control and
display unit E265– Climate control menu in MMI (Multimedia
Interface) for display of climate control set
values and basic settings
– Front and rear seat heating and seat
ventilation
– Heated windscreen Z2
– Energy management control unit J644
The interaction of these components in
coordination with the entire air conditioning
system forms a control loop and permits
comfortable front and rear climate control to
suit all requirements.
SSP282_098

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A distinction is made between two air
conditioner unit versions
– 2-zone front and rear climate
control
– 4-zone front and rear climate
control
and three types of control and
display unit
– Air conditioner control panel with
no seat heating/ventilation
– Air conditioner control panel with
seat heating
– Air conditioner control panel with
seat heating and seat ventilation
(identified by part number index).
SSP282_099
Self-diagnosis
Fault diagnosis and measured value blocks
for air conditioner and seat heating system
can be read out by way of address words 08
"Air conditioner/heater electronics" and 28
"Rear climate control". The functions of and
exact procedure for self-diagnosis and
assisted fault-finding with VAS 5051 can be
found in the Heating/Air Conditioner
Workshop Manual for the relevant vehicle
model.
Operating principle
When the ignition is switched on, the
Climatronic control unit J255 starts up with
the same temperature, air distribution and
fresh-air blower speed settings etc. as were
applicable the last time the ignition was
switched off by way of the appropriate key or
using fingerprint recognition.
If fingerprint recognition has been
implemented, this has priority over key
recognition (refer also to SSP 287 – Audi A8 ´03
Electrical Components).
Personalised settings
The following settings can be made for each
climate control zone (front left, right and,
optionally, with 4-zone climate control rear left
and right):
– Left/right temperature
– Air flow
– Left/right air distribution
– Left/right seat heating
– Left/right seat ventilation
– Operating modes (AUTO for driver and front
passenger, temperature-adjustable centre
vents, automatically controlled
recirculated-air mode, ECON)
The heated windscreen can be activated by
way of the air conditioner defrost button or
the air conditioner control unit automatically
switches on the electric heated windscreen if
the appropriate conditions are satisfied
(windscreen defrost or automatic mode on
cold starting).
The Climatronic J255 and heated windscreen
J505 control units communicate by way of the
LIN bus. The Climatronic control unit transmits
the specified windscreen heating power to the
heated windscreen control unit on the LIN bus.
Heating/Air Conditioner
Key recognition takes place in the case of
remote control (radio or key transponder),
with the driver identification control unit
providing the Climatronic control unit J255
with the appropriate information by way of
the CAN bus.
The electrically heated windscreen is only
supplied with the amount of power which can
currently be drawn from the electrical system
without draining the battery. This is
monitored by the energy management
control unit J644.
As is the case with the Audi A4, the
windscreen is heated by applying voltage to a
metallic foil fitted in the glass (refer to
SSP 213).
As in the Audi A4, the air conditioner
compressor is regulated as a function of load
and controlled externally by way of the
compressor regulating valve (refer to
SSP 240). The Climatronic control unit J255 is
connected to the convenience CAN, via
which diagnosis is also performed.
A manual air conditioning system is not
available.

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3
36
Auto
21,5° C
63
3
The current air conditioner settings are stored
automatically and assigned to the
appropriate remote control key. On vehicles
with Audi one-touch memory (optional), the
current setting is also assigned to the
corresponding fingerprint. Air conditioning system control via MMI
All air conditioning system set values and
basic settings (setup) can be displayed by
way of the MMI. This applies both to the
Climatronic control unit button functions and
to setup.
If the air conditioning system is activated
with the MMI switched on, the air conditioner
function settings can be called up and altered
by way of the multimedia control panel. The
functions indicated in the corners of the
displayed mask are activated using the
softkeys.
Basic setting (setup)
The basic air conditioner settings can only be
altered when the MMI is active. This involves
pressing the SETUP button on the Climatronic
control unit.
The following functions can be selected:
– ECON ON/OFF
– Automatic air recirculation active/inactive
– Synchronisation active/inactive
– Centre vent (temperature-adjustable)
settings between - 3 and + 3
– Auxiliary heater active/inactive
– Auxiliary ventilation active/inactive
– Auxiliary heater/ventilation operating time
15 min./30 min./45 min./60 min.
– Auxiliary heater/ventilation timer status for
timers T1, T2, T3 ON/OFF
– Solar mode active/inactive (solar cells
C20)
– Rear control ON/OFF
The desired settings can be called up and
altered with the driver's/front passenger's
control knob on the Climatronic control unit.
SSP282_112
SSP282_113
low high
Econ
Distribution Seat ventilation
Blower Seat heatingAC - driver
Blower Seat heatingAC setup
Distribution Seat ventilation
Off
Autom. air recirculationOff
Synchron.Off
Centre vent