D3 1

The design and operation of the Audi A8 ´03 are described in the following Self Study Programmes:

SSP 283 – 6-speed automatic gearbox 09E in the Audi A8 '03 - Part 1SSP 284 – 6-speed automatic gearbox 09E in the Audi A8 '03 - Part 2SSP 285 – Running gear in the Audi A8 '03

SSP 286 – New data bus systems - LIN, MOST, BluetoothTMSSP 287 – Audi A8 '03 - Electrical componentsSSP 288 – Audi A8 '03 - Distributed functions

SSP 289 – Adaptive cruise control in the Audi A8 '03SSP 292 – Adaptive air suspension in the Audi A8 '03SSP 293 – Audi A8 '03 - Infotainment

Other helpful information on the

Audi A8 ´03 can be found on the adjacent CD ROMs.

Electrical system

CAN data bus 2

ContentsPageIntroduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Passenger Protection

System layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Block diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Safety systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Engine, Mechanics

Technical data of V8 4.2 l 5V engine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Technical data of V8 3.7 l 5V engine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25System layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30Electrohydraulic torque reaction support . . . . . . . . . . . . . . . . . . . . . . . . . 32Exhaust system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Fuel tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Automatically controlled starting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Gearbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45Running Gear

Front axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Rear axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504-level air suspension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51System layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Electric parking brake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Adaptive cruise control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Electrical System

Bus topology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Convenience and security electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64Lighting system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Heating/Air Conditioner

Design and operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72Operating principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74Blower unit/air routing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76System layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Block diagram for front air conditioner . . . . . . . . . . . . . . . . . . . . . . . . . . . 86Block diagram for rear air conditioner. . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

The Self Study Programme contains information on design New

Attentionfeatures and functions.

Note

The Self Study Programme is not intended as a Workshop Manual. Values given are only intended to help explain the

subject matter and relate to the software version applicable at the time of SSP compilation.

Use should always be made of the latest technical publications when performing maintenance and repair work.

3

IntroductionIntroductionThe new Audi A8 is designed to replace its predecessor of the same name which achieved a total production figure of 105,092 since its introduction in June 1994. This was the first standard saloon with aluminium body and epitomised a new philosophy in the luxury vehicle sector.

The weight-saving Audi Space Frame ASF

represented a major breakthrough in terms of enhanced vehicle dynamics, whilst at the same time solving the problem of increasing weight.

Active head restraintsfor front seatsConvenience/infotainment controlvia multimedia interface (MMI)This body concept was further perfected in the Audi A2 and the design of the Audi A8 ´03 reflects the experience gained from both projects.

The aim when developing the Audi A8 ´03 was not merely to surpass its predecessor in terms of technical features and details.

3.7 or 4.2 l V8 enginewith intake manifold changeover functionAdaptive cruise control (ACC)with radar sensorin front bumper

4

Headlight with adaptive light functionAs the Audi flagship, the new Audi A8 is

An uncompromising sporty character, clear-intended to symbolise the product identity of cut design, innovative technological systems the next Audi generation.

and the highest possible quality level

combine to provide an unforgettable driving experience.In other words:

Automatic boot lid opening and closing functionAudi at its proverbial best.

(optional)

LED-type tail lights4-level air suspensionElectric parking brake\"Advanced Key\" entry and start authorisation systemSSP282_025

6-speed automatic gearbox 09E5

BodyBrief outline16291894144497616152028971125294450511136SSP282_026Kerb weightTurning circleTank capacity6

1,780 kg12 mapprox. 90 litresGross weightLuggage compartment volumeDrag coefficient2,380 kgapprox. 500 l0.27 Cd714Body

The Audi A8 ´03 sets new standards in its Based on the findings obtained from these class by combining lightweight construction vehicles, it was possible to further reduce the with outstanding stability. This is achieved number of body components and through the use of innovative Audi Space significantly increase the level of automation Frame technology for the body design of the in the production process as compared to the Audi A8.

Audi A8 predecessor model.

The technical progress reflected by the unique body concept stems from the

consistent implementation of experience gained from the aluminium Audi A8 and A2 models.

SSP282_027

The static torsional rigidity of the new Audi A8 Characteristic features of the new structure:body is 60 % higher than that of the previous Audi A8 body.

– Large castings with numerous integrated A crucial contribution is made to the functions and a high degree of joint increased rigidity level by the advanced strength

Audi Space Frame structure.

– IHF* sections – optimum cross sections at all locations, for example at side of roof frame

– Sheet metal panels with high levels of local rigidity thanks to the use of special

technologies designed to achieve differing functional cross sections and structures

*IHF = Internal high-pressure forming

7

BodyA-pillarThe A-pillar is made of two cast shells connected by rivets and welds. The shells enclose the sill panel at the bottom and the continuous roof frame at the top.SSP282_029

Sill panel

Use is made for the sill panel of a 3-piece extruded section.

The extruded section must be replaced in the event of sill panel damage.

Depending on the nature of the damage,

either the entire section has to be replaced or parts of it by way of three separating sleeves.

SSP282_030

8

Rear end

The rear end has been completely

redeveloped. The two large central castings are the one connecting the sill panel/longitudinal member and the C/D-pillar connecting element.

The sill panel/longitudinal member connecting element is the largest casting. It supports the entire rear sub-frame and links the rear longitudinal member to the sill panel. Its great rigidity is designed to protect the tank in between in the event of a rear-end collision.

SSP282_032

Large upper castings

Extruded sectionsThe C/D-pillar connecting element (large upper casting) accommodates the

suspension strut at the top and the seat belt at the front, in addition to forming the

terminating side section of the roof frame. The large upper and lower castings are interlinked by way of two straight extruded sections and form the framework for the air suspension strut holder.

Large lower castings

SSP282_0339

BodyBoot lidFoam encasingElectronic boot lid lockwith microswitchSSP282_035Motor for automatic closing aid

Bowden cable

Catch

A standard feature is an automatic closing aid, which is actuated by a Bowden cable separately from the catch. After the latch has closed, a mechanism pulls the catch downwards, overcoming the build-up of

pressure occurring. On locking, a microswitch in the boot lid lock transmits a signal to the control unit to activate the automatic closing aid.

The drive unit is only encased in foam and inserted between side panel and battery.

10

Automatic boot lid

Hinge mechanism(open)

Boot lid

control unit J605

Button in driver's doorButton on boot lidVehicle key

SSP282_036

Pressing the button in the driver's door or on In the event of manual boot lid actuation, the the boot lid, or remote control actuation, electric motor is disconnected by way of a effects release and motor-driven opening of magnetic coupling, thus permitting the boot the boot lid. Automatic boot lid closing can lid to be moved by hand. On closing the boot only be implemented by way of the boot lid lid, the drive is deactivated via a microswitch button.

at the latch and the automatic closing aid activated.

An electric motor flanged directly to the

swivel joint of the right boot lid hinge opens or closes the boot lid.

As a general rule, interruption of automatic actuation always causes the boot lid to be disconnected from the drive unit and thus set to manual mode.

11

BodyFront doorsThe doors are made up of a combination of aluminium panels, aluminium sections and aluminium castings. Optimised rib geometry and wall thickness in the hinge and lock mounting castings formed the basis for ideal implementation of the lightweight construction concept.

Door shell and door frame are connected at the door pre-assembly stage by means of fitted bolts to ensure the accurate

assignment of both components. Window lifter frame, window lifter motor/gear

mechanism, door control unit and speaker are pre-assembled on a base plate and boltedto the door subframe.

SSP282_039

Rear doors

Large, high-strength side impact members are integrated into the door to provide even load distribution in the event of side impact.

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Seats

Backrest adjustment –

The angle of the top 1/3 of the backrest can be adjusted by 15° Crash-active, electronic for enhanced shoulder comfort.head restraint with 70 mm height adjustmentLumbar support with massage function over a length of 60 mmThorax/pelvis side airbagBackrest fanSSP282_116Electric seat depth adjustment – As the structure moves forwards it pulls the padding with it and so extends the seat area by 50 mm.

Seat cushion fan

A new seat concept was developed for the Extra features of sports and comfort seats:Audi A8 ´03.

The basic seat features the following – Electric top 1/3 backrest adjustmentstandard functions:

– Electric seat depth adjustment– Electric seat length, height and angle Optional extras for comfort seat:adjustment

– Electric backrest angle adjustment

– Climate function (refer to Page 85)– Front crash-active head restraints (refer to – and/or massage function

Page 21)The massage function is implemented by way The basic seat can additionally be fitted withof rhythmic action of the electromechanical lumbar support, thus massaging and relaxing – Four-way lumbar support

the back muscles.

– Seat memory for driver and front passenger

The fixed rear seat bench versions correspond – Electrically adjustable head restraintsto those of the front seats, with the third head – Electric belt height adjusters

restraint being fully retractable. Electric

individual seats are however only available as \"Basic\" and \"Comfort\" versions.

13

Passenger ProtectionSystem layoutG 283G 284K145J623J285/K75AIRBAGAIRBAGOFFE224AUSEINT16J533N95/G85N131J234E24J526N199E25N200G179N153N154G180N201N202N251G 256N196N198N197N252G 257J393J65514

SSP282_068

Use is made in the Audi A8 ´03 of the 8.4E+ The wide range of sensors permits detection airbag system with the aim of attaining greater not only of head-on collision and side impact,occupant safety whilst reducing the impact. but also of rear-end collisions.This was achieved, for example, by way of two-stage front airbag triggering, active front head restraints and a battery cut-off element.

Key

E24Driver side belt switch

E25Front passenger side belt switchE224Airbag disabling key switch,

front passenger sideG85Steering angle senderG179Side airbag crash sensor,

driver side (B-pillar)

G180Side airbag crash sensor,

front passenger side (B-pillar)

G256Rear side airbag crash sensor,

driver side

G257Rear side airbag crash sensor,

front passenger side

G283Front airbag crash sensor,

driver side

G284Front airbag crash sensor,

front passenger sideJ234Airbag control unit

J285Control unit with display

in dash panel insert

J393Convenience system central

control unit

J526Telephone/telematics control unitJ533Data bus diagnostic interface

(gateway)

J623Engine control unitJ655Battery cut-off relay

K75Airbag warning lamp

K145Airbag disabled warning lamp,

front passenger sideN95Driver side airbag igniter

N131Airbag igniter 1, front passenger sideN153Belt tensioner igniter 1, driver sideN154Belt tensioner igniter 2, front passenger side

N196Rear belt tensioner igniter, driver side

N197Rear belt tensioner igniter, front passenger side

N198Rear belt tensioner igniter, centre

N199Side airbag igniter, driver sideN200Side airbag igniter, front passenger sideN201Rear side airbag igniter, driver side

N202Rear side airbag igniter, front passenger side

N251Curtain airbag igniter, driver sideN252

Curtain airbag igniter, front passenger sideT16

16-pin connector

(diagnostic connection)

15

Passenger ProtectionBlock diagram1513G283J655G284G179E2242J234F138N95N131N199N200N201N202Key

E24Driver side belt switch

E25Front passenger side belt switchE224Airbag disabling key switch,

front passenger sideF138Airbag coil connector/return spring

with slip ringG179Side airbag crash sensor,

driver side

G180Side airbag crash sensor,

front passenger side

G256Rear side airbag crash sensor,

driver side

G257Rear side airbag crash sensor,

front passenger side

G283Front airbag crash sensor,

driver side

G284Front airbag crash sensor,

front passenger side

J234Airbag control unitJ655Battery cut-off relayN95N131N153N154N196N197N198N199N200N201N202

Driver side airbag igniter

Airbag igniter 1, front passenger sideBelt tensioner igniter 1, driver sideBelt tensioner igniter 2, front passenger side

Rear belt tensioner igniter, driver sideRear belt tensioner igniter, front passenger side

Rear belt tensioner igniter, centreSide airbag igniter, driver sideSide airbag igniter, front passenger sideRear side airbag igniter, driver side

Rear side airbag igniter, front passenger side

16

G180G256G257E24E254567N251N252N153N154N196N198N197SSP282_069Additional signals

N251Curtain airbag igniter, driver side1Battery A (positive)

N252Curtain airbag igniter,

front passenger side

2

Positive connection to starter B and alternator C3Terminal 58s

4Drive system CAN (High)5

Drive system CAN (Low)Colour code

6

Crash signal

= Input signal= Output signal7

Airbag disabled warning lamp,front passenger side K145

= Positive supply= Earth

17

Passenger ProtectionSafety systems2-stage front airbagsThe 2-stage triggering of the front airbags provides optimum restraint in crash situations at around 30 km/h. There is a separate firing pellet for each stage in the driver's and front passenger's airbag. These ignite successively at specified time intervals.Ring airbag

SSP282_070

A so-called \"ring airbag\life belt, is used on the driver's side. This radial inflation method affords particular protection to drivers sitting very close to the steering wheel. The centre of the steering wheel does not move as the airbag unfolds and is inflated in the form of a ring. A

rectangular fabric layer is additionally sewn to three sides of the ring. One side is left free to allow the airbag to slide over the non-moving centre section of the steering wheel.

This airbag design satisfies the requirements of the latest American legislation and involves compliance with biomechanical values for so-called \"Out Of Position\" (OOP) driver posture. If the driver's head or upper part of the body is very close to the steering wheel at the time of airbag unfolding (OOP), this airbag concept can prevent serious injury.

18

Front passenger's airbag deactivationAn optional feature of the Audi A8 ´03 is a new airbag disabling key switch for the front passenger's side E224.

Two resistance paths are integrated into this switch to permit detection of individual faults. A fault in the key switch is indicated by

flashing of the front passenger's side airbag disabled warning lamp K145 located in the centre console next to the hazard warning switch.

SSP282_081Front knee airbags (USA)

SSP282_114

The USA version of the Audi A8 ´03 is fitted In this way, severe impact in the knee zone is with driver's and front passenger's knee avoided.

airbags as standard, thus optimising driver Knee airbags are required by legislation in the and front passenger movement in a crash USA.

situation.

19

Passenger ProtectionDetection of rear-end collisionRear-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.Up-front sensorsFor the first time, use is made in the

Audi A8 ´03 of so-called up-front sensors.

These take the form of two additional front-end acceleration sensors on the right and left beneath the corresponding headlight.

SSP282_072

Lateral acceleration sensorsFurther acceleration sensors are located at the B and C-pillars.

C-pillar sensorB-pillar sensor

SSP282_073

20

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 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.restraint.

Belt tensioners

Five belt tensioners are fitted as standard. There is no centre belt tensioner if the rear seats are electrically adjustable.

SSP282_082

21

Passenger ProtectionBattery cut-off relay J655The battery cut-off relay is a battery isolating element designed to disconnect starter and alternator power from the electrical system in the event of a crash.Terminal30, battery87Terminal 15Vehicle earthCrash signalDiagnosisPinAB1234Input/outputInput (screw connection)Output(screw connection)Input (plug connection)Input (plug connection)Input (plug connection)Input (plug connection)DescriptionUbat. term. 30/batteryOutputPositive power supply, interruptibleEarth fromairbag control unit J234Crash signal fromairbag control unit J234Diagnostic wire fromairbag control unit J234Block diagram

J644Energy management control unitJ655Battery cut-off relay

3015A+431J655-BJ644312SSP282_076

22

Fitting location

The battery cut-off relay is located in front of the battery.

Triggering

SSP282_083

The airbag control unit J234 provides the battery cut-off element with the triggering command via a discrete wire.

Triggering of this element by the airbag

control unit causes a white panel to appear in the element window instead of a copper coil. Following isolation, the battery cut-off

element can be manually reset by way of the yellow knob.

Control element test

The control element test in the airbag control unit also triggers the battery cut-off relay. It should be ensured that the relay is manually SSP282_079

reset, as otherwise the battery cannot be charged.

WindowReset knobSSP282_07723

Engine, MechanicsTechnical dataV8 4.2 l 5V engineEngine codeletters: BFMCapacity:Bore:Stroke:Compression ratio:Power:Torque:Camshaft adjustment range:Valves:Engine

management:Emissionstandard:Firingorder:Capacities:Consumption:

Acceleration0 - 100 km/h:

Fuel:

CS = Crankshaft

24

4,172 cm384.5 mm93.0 mm11 : 1246 kW (335 hp)at 6,500 rpm430 Nm at 3,500 rpm22° CS advance5 per cylinder

ME7.1.1

EU 4

1 - 5 - 4 - 8 - 6 - 3 - 7 - 2 7.5 l engine oil (incl. filter)Urban: 17.5 - 17.6 l/100 kmNon-urban: 8.7 - 8.8 l/100 km Average: 11.9 - 12.0 l/100 km

0 - 80 km/h – 4.8 s0 - 100 km/h – 6.3 sPremium Plus Unleaded 98/95 RON

460240440220420200400180]m380160]N[ 360140Wke[ur q340120erwTo320100Po300802806026040200040006000Engine speed [rpm]

SSP282_002

SSP282_012

V8 3.7 l 5V engineEngine code

letters: BFLCapacity:Bore:Stroke:Compression ratio:Power:

Torque:Camshaft adjustment range:Valves:Engine

management:Emissionstandard:Firingorder:Capacities:Consumption:

Acceleration0 - 100 km/h:

Fuel:

4602403,697 cm

344022084.5 mm

42020040018082.4 mm

]m380160]NW[ 360140ke[11 : 1

ur q340120erwTo206 kW (280 hp)

320100Poat 6,000 rpm3008028060360 Nm at 3,750 rpm

2604020004000600013° CS advanceEngine speed [rpm]

5 per cylinder

SSP282_001

ME7.1.1

EU 4

1 - 5 - 4 - 8 - 6 - 3 - 7 - 27.5 l engine oil (incl. filter) Urban: 17.1 - 17.3 l/100 kmNon-urban: 8.6 - 8.8 l/100 km Average: 11.7 - 11.9 l/100 km

0 - 80 km/h – 5.6 s0 - 100 km/h – 7.3 s

Premium Plus Unleaded 98/95 RON

SSP282_011

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Engine, MechanicsV8 5V 3.7 l/4.2 l engineThe 3.7 l and 4.2 l V8 engines were adopted from the predecessor model with certain modifications.These modifications relate to the intake and exhaust systems and are described in the following.Design and operation are described in SSP 217.Variable-intake manifold in 4.2 l engineThis takes the form of a 2-stage variable-intake manifold made of a die-cast magnesium alloy, bonded and bolted together in four sections.The two-stage design permits the use of two intake paths with large cross section.

The intake manifold must be replaced as a complete unit when performing repairs.SSP282_013

26

– Long intake path, 705 mm

– Changeover flap closed for high torque

Each of the two splined shafts is fitted with four flaps per cylinder bank.

The shape of the rubber-encased flaps ensures unimpeded air flow in the torque position and reliable power position sealing of the duct. This is a prerequisite for

utilisation of the gas-dynamic resonance effects. In the power position, the backs of the flaps take on the shape of the duct wall, thus allowing low-resistance intake air flow into the cylinders.

Mechanical couplings provide a link with the vacuum units for adjustment of the two shafts and thus the intake manifold flaps.

– Short intake path, 322 mm

– Changeover flap open for high power with high air throughputChangeover from long to short at 4,480 rpmChangeover from short to long at 4,320 rpm

SSP282_014SSP282_016

SSP282_015

27

Engine, MechanicsVariable-intake manifold in 3.7 l engineChangeover flap, stage 3Intake air (inlet)Vacuum unitChangeover flap, stage 3ic ntroece el valvmeFrorottlThtohrttleInjectormountsChangeover flap, stage 2(open)Vacuum unitChangeover flap, stage 2

Resonance tube, cyl. 5(inlet end)

SSP282_017

This is the same 3-stage variable-intake

manifold as previously fitted in the V8 engine.

Due to the piston stroke of only 82.4 mm, three resonance tube lengths are required to achieve resonance effects in the lower engine speed range.Changeover points:– Long to shortat 3,280 rpm– Short to longat 3,120 rpm– Short to shorterat 5,120 rpm– Shorter to shortat 4,920 rpm

Operation of the 3-stage variable-intake manifold is described in SSP 217.

28