992203_2002_NewTechnology

NewTechnology 2002Design and Function

Self-Study ProgramCourse Number 992203

Audi of America, Inc.3800 Hamlin RoadAuburn Hills, MI 48326Printed in U.S.A.February 2002

Audi of America, Inc.Service TrainingPrinted in U.S.A.Printed 2/2002Course Number 992203

2002 Audi of America, Inc.

All rights reserved. All information containedin this manual is based on the latestinformation available at the time of printing andis subject to the copyright and other intellectualproperty rights of Audi of America, Inc., itsaffiliated companies and its licensors. All rightsare reserved to make changes at any timewithout notice. No part of this document maybe reproduced, stored in a retrieval system,or transmitted in any form or by anymeans, electronic, mechanical, photocopying,recording or otherwise, nor may thesematerials be modified or reposted to other siteswithout the prior expressed written permissionof the publisher.

All requests for permission to copy andredistribute information should be referred toAudi of America, Inc.

Always check Technical Bulletins and theAudi Worldwide Repair Information Systemfor information that may supersede anyinformation included in this booklet.

Trademarks: All brand names and productnames used in this manual are trade names,service marks, trademarks, or registeredtrademarks; and are the property of theirrespective owners.

iTable of Contents

The Self-Study Program provides you with informationregarding designs and functions.

The Self-Study Program is not a Repair Manual.For maintenance and repair work, always refer to thecurrent technical literature.

Important/Note!

New !

Introduction ................................................................................................... 1Audi New Technology 2002

Engine Valve Train Variable Valve Timing .............................................. 2The Task of Variable Valve Timing, Operation of Variable ValveTiming, Intake Camshaft, Exhaust Camshaft, Oil System,Engine Management for Variable Valve Timing

Engine Cooling Electronically Controlled............................................. 16Electronically Controlled Cooling System Overview,The Coolant Temperature Level, Coolant Thermostat Housingwith Map Controlled Engine Cooling Thermostat F265, TheCoolant Temperature Set Points, Engine Coolant Temperature(ECT) Sensor G62 and Engine Coolant Temperature (ECT) Sensor(On Radiator) G83, Map Controlled Engine Cooling ThermostatF265, Coolant Fan V7 and Coolant Fan -2- V177

Fuel Supply 1.8T ..................................................................................... 25Pressure-Regulated Fuel Filter

Exhaust System Exhaust Flap ............................................................... 26Exhaust Flap 3.0-Liter V6, Exhaust Flap VacuumSystem Overview, Exhaust Flap Functional Diagram

Suspension Pneumatic Damping Control ............................................ 31Pneumatic Damping Control Shock Absorbers

Tires Tire Pressure Monitoring .............................................................. 36The Tire Pressure Monitoring System, System Components,System Functions, Tire Pressure Monitoring Functional Diagram

Steering Servotronic II ........................................................................... 66Servotronic II Variable Effort Power Steering,Servotronic II System Overview

Electrical System......................................................................................... 68CAN Data Bus, Compass, Bi-Xenon Headlights, Audi Telematicsby OnStar, Audi Digital Phone by Motorola, Symphony II RadioTransport Mode

Knowledge Assessment ............................................................................. 81

Introduction

1

Audi New Technology 2002

In keeping with the Audi tradition ofproducing the best-engineered and mostappealing cars in the world, Audi isintroducing technical innovations andimprovements in many vehicle systems forthe 2002 model year. From performanceand handling to convenience, comfort, andsafety; from social responsibility to thesheer fun of driving; Audi continues to earnits reputation as a manufacturer of world-class cars with a technical edge.

Some of the latest Audi technologies beingintroduced to the North American marketfor 2002 include:

Variable valve timing

Electronically controlled engine cooling

1.8T engine fuel delivery modifications

Exhaust system noise reduction

Pneumatic damping control shockabsorbers

Tire pressure monitoring

Servotronic II variable effort steering

CAN data bus

Electronic compass

Bi-xenon headlights

Audi Telematics by OnStar

Digital phone by Motorola

Symphony II radio transport mode

This Self-Study Program describes thedesign and function of these technicalinnovations.

SSP248/067

SSP222/035a

SSP242/051

78500018

Engine Valve Train Variable Valve Timing

2

The Task of Variable Valve Timing

The valve timing illustrated hereis intended to demonstrate thebasic principle and the effects ofvariable valve timing. Each engineapplication has valve timingadapted to its own mechanicsand engine management system.The quantity and appearance ofcomponents will vary from oneapplication to another.

Variable valve timing sets the mostadvantageous valve timing for the engine ineach operating mode: idle, maximumpower, and torque; as well as for exhaustgas recirculation.

Idle

At idle, the intake camshaft is set so thatthe intake valves open and close late. Theexhaust camshaft is set so that exhaustvalves close well before top dead center(TDC). Because there are only smallamounts of residual gases fromcombustion, engine idle is smooth.

Power

To achieve good power at high enginespeeds, the exhaust valves are openedlate. This allows the expanding burninggases to act against the pistons longer.

The intake valves open after top deadcenter and close well before bottom deadcenter (BDC). This enables the dynamicself-charging effect of the entering air, andincreases power output.

TDC

BDC

IC

IO

EO

TDCEC

IO

IC

BDCEO

SSP246-001

SSP246-002

EC

Intake IO Intake Opens

Compression IC Intake Closes

Power EO Exhaust Opens

Exhaust EC Exhaust Closes

Idle

Power


3

Torque

To achieve maximum torque, goodvolumetric efficiency is needed. Thisrequires that the intake valves be openedearly. Because the intake valves open early,they close early as well. This keeps thefresh gases from being pushed back outthe intake valve port.

The exhaust camshaft closes the exhaustvalves just before top dead center.

Exhaust Gas Recirculation

Internal exhaust gas recirculation can beachieved by adjusting the intake andexhaust camshafts for a period of valveoverlap, when both the intake and exhaustvalves are open. The amount of overlapdetermines the amount of recirculatedexhaust gas.

The intake camshaft is set so that it opensthe intake valves well before top deadcenter. The exhaust camshaft does notclose the exhaust valves until just beforetop dead center. As a result, both valves areopen and some of the exhaust gas isrecirculated in the cylinder for reburningduring the next power stroke.

The advantage of internal exhaust gasrecirculation over external exhaust gasrecirculation is the fast reaction of thesystem and very even distribution of therecirculated exhaust gases.

TDCEC

BDC EO

IC

IO

SSP246-003

TDC

EC

IO

IC

BDC EO

SSP246-004

Intake IO Intake Opens

Compression IC Intake Closes

Power EO Exhaust Opens

Exhaust EC Exhaust Closes

Torque

Exhaust GasRecirculation


4

Operation of Variable Valve Timing

The Motronic Engine Control Module J220controls the variable valve timing. To dothis, it requires information from varioussensors about engine speed, engine loadand temperature, and the positions of thecrankshaft and the camshafts.

To adjust the camshafts on the cylinderbank shown, the Motronic Engine ControlModule J220 actuates Valve 1 for CamshaftAdjustment N205 and Camshaft

Adjustment Valve 1 (Exhaust) N318. They inturn open oil galleries in the controlhousing. Engine oil flows through thecontrol housing and camshafts into thecamshaft adjusters. The inner rotors (pivotmotor rotors) rotate and adjust the intakeand exhaust camshaft positions inaccordance with the specificationsprogrammed into the Motronic EngineControl Module J220.

SSP246-012

Camshaft Position(CMP) Sensor G40

Camshaft Position(CMP) Sensor 2 G163

Intake Camshaft

Exhaust Camshaft

Valve 1 for CamshaftAdjustment N205

CamshaftAdjustment Valve 1(Exhaust) N318

Oil Pump

Engine Speed

Air Mass and Air Temperature (Engine Load)

Coolant Temperature

MotronicEngine ControlModule J220 One cyllinder bank

of W12 engine shown.


5

Intake Camshaft

Intake Camshaft Adjustment

Each intake camshaft is regulated by theMotronic Engine Control Module J220 overthe entire speed range of the engine. Themaximum amount of adjustment possible isthrough 52 degrees of crankshaft angle.Adjustment is determined by a control mapstored in the Motronic Engine ControlModule J220.

As used here, map refers toan electronic database thatsets up the relationship betweenincoming sensor informationand outgoing control signals.Maps are also referred to aslook-up tables.

Intake Camshaft Adjuster Design

The adjusting mechanism of each intakecamshaft adjuster consists of:

A combined housing and outer rotorconnected directly to the timing chainor belt.

An inner rotor (pivot motor rotor)attached to the end of the camshaft.

The adjusters are locked mechanicallyuntil the necessary engine oil pressure hasbuilt up.

Using a mechanical detent device, a spring-loaded differential pressure pin preventsthe camshaft from being adjusted duringthe engine start cycle.

The adjuster is designed to move to theretard position and remain locked therewhenever the engine is turned off.

The rising engine oil pressure unlocks thespring-loaded differential pressure pins.

Outer RotorInner Rotor(Pivot Motor Rotor)

Oil GalleriesSSP246-155

Intake Camshaft Adjuster

Camshaft AdjusterInner Rotor withConnection toCamshaft

SSP255/021

MechanicalDetent


6

How the Intake Camshaft is Advanced

For exhaust gas recirculation and increasingtorque, each intake camshaft must be setso that the intake valves open well beforetop dead center.

To advance valve timing on the cylinderbank shown, the Motronic Engine ControlModule J220 actuates Valve 1 for CamshaftAdjustment N205 which adjusts theposition of the control piston in the controlhousing.

The control housing oil gallery for timingadvance is opened up in accordance withthe new position of the control piston.

With the oil gallery opened, engine oilunder pressure flows through the controlhousing and into the forward ring channel inthe intake camshaft.

From there the pressurized oil flowsthrough five passages drilled through to thefront face of the camshaft and into the fiveadvance chambers of the camshaftadjuster, where it presses against thevanes of the inner and outer rotors. Thiscauses the inner rotor (pivot motor rotor) torotate to an advanced position within theouter rotor.

Since the camshaft is fixed to the innerrotor (pivot motor rotor) and the crankshaftis mechanically linked to the outer rotor,this effectively rotates the intake camshaftin the direction of crankshaft rotation andthe intake valves open sooner.

If the variable valve timingfunction fails, the camshaftadjuster will be set by engineoil pressure to the basicretarded position.

Engine OilPressure

Oil Return

Oil Return

Control Piston Valve 1 for CamshaftAdjustment N205

FrontDrilledPassage

Ring ChannelsControl Housing

Timing AdvanceOil Gallery

SSP246-150

Inner Rotor(Pivot MotorRotor)

One cylinderbank shown.


7

How the Intake Camshaft is Retarded

When the engine is idling or when a lot ofpower is required from the engine, eachintake camshaft is rotated so that the intakevalves open late after top dead center.

To retard the intake camshaft on thecylinder bank shown, the Motronic EngineControl Module J220 actuates Valve 1 forCamshaft Adjustment N205, which opensthe gallery for timing retardation by movingthe control piston.

Engine oil under pressure flows through thecontrol housing into the rearward ringchannel of the camshaft.

From there the pressurized oil flowsthrough drilled passages in the camshaft tothe pocket hole of the securing bolt for thecamshaft adjuster.

The pressurized oil then flows through fivedrilled passages in the camshaft adjusterand into the oil chamber for timingretardation where it presses against thevanes of the inner and outer rotors. Thiscauses the inner rotor (pivot motor rotor) torotate to a retarded position within theouter rotor.

This movement effectively rotates theintake camshaft in the opposite directionfrom crankshaft rotation and the intakevalves open later.

At the same time that the oil gallery fortiming retardation is opened, the controlpiston opens the oil return for the galleryfor timing advance, relieving the pressurethere. The rotation of the inner rotor (pivotmotor rotor) in the retard direction pushesthe oil out of the timing advance chamberthrough the timing advance oil gallery.

Engine OilPressure Oil Return

Control Piston

Oil Return

TimingRetardationOil Gallery

Pocket Hole forSecuring Bolt

Control HousingRing Channels

FrontDrilledPassage

Inner Rotor(Pivot MotorRotor)


SSP246-151



8

How Regulation Works

Regulation enables continuous variation ofthe position of each intake camshaftbetween advanced and retarded through amaximum adjustment range of 52 degreesof crankshaft angle. On the cylinder bankshown, the Camshaft Position (CMP)Sensor G40 provides a signal to theMotronic Engine Control Module J220which allows it to monitor the exactposition of the intake camshaft at any givenmoment. The control map in the MotronicEngine Control Module J220 determinesthe intake camshaft adjustment using thiscamshaft position information as well asengine load, speed, and coolanttemperature readings.

When the control map calls for advancedtiming, the Motronic Engine ControlModule J220 activates the Valve 1 for

Camshaft Adjustment N205, which movesthe control piston in the advance timingdirection. Pressurized oil is diverted throughthe control housing and drilled passages inthe camshaft into the camshaft adjusterand moves the camshaft into an advancedposition. Moving the control piston in theadvanced direction simultaneously opensthe oil return through the oil channel forretarding timing.

When the desired angle of adjustment isattained, the control map initiatesmovement of the control piston to aposition that maintains equal pressure inboth camshaft adjuster chambers tomaintain the adjustment angle.

To move the camshaft in the retard timingdirection, the regulation process is similarbut pressurized oil flow is reversed.


SSP246-150a

Pressure to Advance Timing Equalized Pressureto Maintain Adjustment


SSP246-152One cylinderbank shown.


9

Exhaust Camshaft

Exhaust Camshaft Adjustment

In contrast to the intake camshaftadjustment which is continuously variableover the entire range of 52 degrees ofcrankshaft angle, the adjustment of eachexhaust camshaft is essentially on oroff to advance the exhaust camshafttiming or return it to normal. Theadjustment variation between these twopositions is 22 degrees of crankshaft angle.

Outer Rotor

Oil Galleries

Wider Vanes

Inner Rotor(Pivot Motor Rotor)

SSP246-156

Exhaust Camshaft Adjuster

Exhaust Camshaft Adjuster Design

The adjusting mechanism of the exhaustcamshaft adjuster is nearly identical to thedesign of the intake camshaft adjuster:

A combined housing and outer rotorconnected directly to the timing chainor belt.

An inner rotor (pivot motor rotor)attached to the end of the camshaft.

The vanes of the inner rotor (pivot motorrotor) are wider to limit adjustment travelto the smaller 22 degrees of crankshaftangle required of the exhaust camshaft.


10

Exhaust Camshaft Normal Position

Each exhaust camshaft is in its normalposition when the engine is being startedand at engine speeds above idle. In thenormal position, the exhaust valves closejust before top dead center. Each exhaustcamshaft is in the normal position in theengine operating modes for maximumpower and torque; as well as for exhaustgas recirculation. Under these conditions,on the cylinder bank shown the CamshaftAdjustment Valve 1 (Exhaust) N318 is notactuated.

How the Normal Position Works

In the normal position, the exhaustcamshaft is positioned so that the exhaustvalves close shortly before top dead center.The Camshaft Adjustment Valve 1 (Exhaust)N318 on the cylinder bank shown is notactuated by the Motronic Engine ControlModule J220.

In the normal position, the oil gallery fortiming retardation is open. Through thisoil gallery, engine oil under pressurereaches the rearward ring channel in theexhaust camshaft.

From there the pressurized oil flowsthrough drilled passages in the camshaft tothe pocket hole of the securing bolt for thecamshaft adjuster.

The pressurized oil then flows through fivedrilled passages in the camshaft adjusterand into the oil chamber for normal positionwhere it presses against the vanes of theinner and outer rotors. This causes theinner rotor (pivot motor rotor) to rotate tothe stops at the normal position within theouter rotor, rotating the camshaft alongwith it.

The exhaust camshaft on the cylinder bankshown remains in this position as long asthe Camshaft Adjustment Valve 1 (Exhaust)N318 solenoid is not actuated.

At the same time that the oil gallery fortiming retardation pressure is open, the oilreturn for the gallery for timing advance isopen, relieving the pressure there. Therotation of the inner rotor (pivot motor rotor)in the retard direction pushes the oil out ofthe timing advance chamber through the oilgallery for timing advance.


11


OuterRotor


Control Piston

Oil ReturnEngine OilPressure

Oil Return

Oil Gallery forTiming Retardation


Oil Gallery forTiming Advance

ControlHousing

Ring Channel

FrontDrilledPassage

SSP246-157


Exhaust Camshaft Advanced Position

Each exhaust camshaft is set to theadvanced position at engine speeds fromidle to about 1,200 rpm.

How the Exhaust Camshaft is Advanced

To advance exhaust valve timing on thecylinder bank shown, the Motronic EngineControl Module J220 actuates theCamshaft Adjustment Valve 1 (Exhaust)N318, which adjusts the position of thecontrol piston in the control housing.

The control housing oil gallery for timingadvance is opened up in accordance withthe new position of the control piston.

With the oil gallery opened, engine oilunder pressure flows through the controlhousing and into the forward ring channel inthe exhaust camshaft.

From there the pressurized oil flowsthrough five passages drilled through to thefront face of the camshaft and into the fiveadvance chambers of the camshaftadjuster, where it presses against thevanes of the inner and outer rotors.This causes the inner rotor (pivot motorrotor) to rotate to an advanced positionwithin the outer rotor.

Since the camshaft is fixed to the innerrotor (pivot motor rotor) and the crankshaftis mechanically linked to the outer rotor,this effectively rotates the intake camshaftin the direction of crankshaft rotation andthe exhaust valves open and close earlier.

At the same time that the oil gallery fortiming advance pressure is open, the oilreturn for the gallery for timing retardationis open, relieving the pressure there. Therotation of the inner rotor (pivot motor rotor)in the advance direction pushes the oil outof the timing retard chamber through the oilgallery for timing retardation.

If the variable valve timingfunction fails, the exhaustcamshaft adjuster will remainin the normal position, theexhaust valves close justbefore top dead center.

Oil System

The variable valve timing system operatesat an oil pressure of 10.2 psi (70 kPa) andabove. Oil flow through the exhaust andintake camshafts is virtually identical.


12


13

Control Piston

Oil ReturnEngine OilPressure

Oil Return

Oil Galleryfor TimingRetardation

Oil Gallery forTiming Advance


ControlHousing

Ring Channels

Front DrilledPassage


Outer Rotor


SSP246-156a


Engine Management forVariable Valve Timing

Typical System Overviewfor V6 Engines

Motronic EngineControl Module J220


Camshaft AdjustmentValve 1 (Exhaust) N318

Data LinkConnector (DLC)Wire Connector TV14

Camshaft Position (CMP)Sensor G40

Camshaft Position (CMP)Sensor 2 G163

Engine Speed (RPM)Sensor G28

Mass Air Flow (MAF)Sensor G70 (In SomeApplications Combinedwith Intake Air Temperature(IAT) Sensor G42)

Engine CoolantTemperature (ECT)Sensor G62

SSP246-029


14




Camshaft AdjustmentValve 2 (Exhaust) N319


15

Learning Ability of the System

The entire variable valve timing systemis adaptive. This adaptability compensatesfor component and assembly tolerancesand wear.

The Motronic Engine Control Module J220initiates adaptation when the engine isidling and the coolant temperature isgreater than 140F (60C).

During adaptation, the Motronic EngineControl Module J220 uses signals from the

Engine Speed (RPM) Sensor G28, theCamshaft Position (CMP) Sensor G40,the Camshaft Position (CMP) Sensor 2G163, the Camshaft Position (CMP)Sensor 3 G300, and the Camshaft Position(CMP) Sensor 4 G301, to check the idlesettings for the intake and exhaustcamshafts. If the actual value does notagree with the control map specificationstored in the Motronic Engine ControlModule J220, the camshaft positions areadjusted to match the specification.

Adaptation Value

Actual Value

Specification

TDC

BDC SSP246-009

Electronically Controlled CoolingSystem Overview

The aim of developing an electronicallycontrolled cooling system was to be ableto set the operating temperature of theengine to a specified value based on theload state.

An optimal operating temperature is setaccording to maps stored in the MotronicEngine Control Module J220 by heating thethermostat electrically and adjusting theradiator fan settings.

Cooling can thus be adapted to the enginesoverall performance and load state.

As used here, map refersto an electronic databasethat sets up the relationshipbetween incoming sensorinformation and outgoingcontrol signals. Maps are alsoreferred to as look-up tables.

Advantages

The advantages of adapting the coolanttemperature to the current operating stateof the engine are:

Lower fuel consumption in the part-throttle range.

Reduced raw CO and HC emissions.

Changes to the conventional coolingcircuit include:

Integration in the cooling circuit throughminimal design modifications.

The coolant distributor housing andthermostat are combined to form a singlemodule.

There is no longer any need for a coolantthermostat on the cylinder head.

Motronic Engine Control Module J220contains the maps of the electronicallycontrolled cooling system.

Electronically controlled cooling isonly used on the 1.8T AMBengine at the time of printing.Other engines will be added inthe future.

16

Engine Cooling Electronically Controlled


17

The Coolant Temperature Level

Engine performance is dependent onproper engine cooling.

In the electronically controlled coolingsystem, the coolant temperatures rangefrom 203F to 230F (95C to 110C)in the part-throttle range and from185F to 203F (85C to 95C) in thefull-throttle range.

Engine load and cooling shouldalways be considered together.

Engi

ne L

oad

Engine Speed

Part-Throttle Range203F to 230F (95C to 110C)

Full-Throttle Range185F to 203F (85C to 95C)

SSP222-013

Coolant Temperature Level as a Functionof Engine Load with Mapped Cooling

Higher temperatures in the part-throttlerange improve efficiency, which in turnreduces fuel consumption and pollutantsin the exhaust gases.

Lower temperatures in the full-throttlerange increase power output. Theinducted air is heated to a lesser degree,boosting performance.


18

Coolant Thermostat Housing withMap Controlled Engine CoolingThermostat F265

The Functional Components

An expansion-element thermostat with awax thermocouple (Map ControlledEngine Cooling Thermostat F265).

Resistance heating in the waxthermocouple.

Pressure springs for mechanicallyclosing the coolant ducts.

One large valve disc and one smallvalve disc.

Function

The Map Controlled Engine CoolingThermostat F265 in the coolant distributorhousing is always immersed in coolant.The wax thermocouple regulates thethermostat opening temperature unheatedas before, but is rated for a differentopening temperature.

The coolant temperature causes the wax toliquefy and expand, producing a liftingmovement of the lifting pin.

This normally happens in accordance withthe new coolant temperature profile of230F (110C) at the engine cylinder headoutlet, without the application of voltage tothe heating resistor integrated into the waxthermocouple.When voltage is applied to the heatingresistor, it heats the wax thermocoupleabove the temperature of the surroundingcoolant. The adjustment of the lifting pinstroke is then determined not only by thecoolant temperature, but also as specifiedby the map stored in the Motronic EngineControl Module J220.

Lifting Pin

Map Controlled EngineCooling Thermostat F265

Small Valve Discfor Closing the SmallCoolant Circuit

Pressure Spring

Electrical Connectionfor Heating Thermostat

Large Valve Discfor Closing theLarge Coolant Circuit

Heating Resistor

SSP222-035


19

The Coolant TemperatureSet Points

Activation of the Map Controlled EngineCooling Thermostat F265 is regulatedby maps to distribute the coolantflow volume between the large and smallcooling circuits.The relevant temperature set points arestored in these maps.The pre-control pulse duty factorinformation is stored in a map.This map is required to determine thecoolant temperature set point when thevehicle is at rest with the engine running.The information required for this purposeis obtained by comparing the actualtemperature and the specified temperatureas factors of engine speed.A temperature constant between 185Fand 230F (85C and 110C) can then beset for the Map Controlled Engine CoolingThermostat F265 based on engine speedand coolant temperature.In the specified coolant temperature 1 mapthe temperature setting is calculated from theengine load (determined by measured intakeair mass) and engine speed.The specified coolant temperature 2setting is calculated from temperature setpoints that are stored based on road speedand intake air temperature in a second map.By comparing maps 1 and 2, the lowervalue is used by the Motronic EngineControl Module J220 as the set point andthe Map Controlled Engine CoolingThermostat F265 is set accordingly.The Map Controlled Engine CoolingThermostat F265 is not activated until atemperature threshold has been exceededand the coolant temperature is just belowthe set point.

Specified Temperature

Engine Speed

Pre

-Con

trol

Pul

seD

uty

Fact

or

SSP222-018

Map Pre-Control Pulse Duty Factor

Nom

inal

Tem

pera

ture

Engine Load(Intake Air Mass)194F

(90C)

Engine Speed

SSP222-016

SSP222-017

Road Speed185F(85C)

Nom

inal

Tem

pera

ture

Intake Air Temperature

Map Specified Coolant Temperature 1

Map Specified Coolant Temperature 2


20

Engine Coolant Temperature (ECT)Sensor G62 and Engine CoolantTemperature (ECT) Sensor(On Radiator) G83

These sensors both operate as negativetemperature coefficient (NTC) sensors. Thecoolant temperature set points are stored inthe Motronic Engine Control Module J220in the form of maps.

The actual coolant temperature valuesare registered at two different points inthe cooling circuit and indicated to theMotronic Engine Control Module J220 inthe form of a voltage signal.

Coolant actual value 1 is measured atthe cylinder head coolant outlet byEngine Coolant Temperature (ECT)Sensor G62 located in the upper level ofthe coolant distributor housing.

Coolant actual value 2 is measured atthe radiator by Engine CoolantTemperature (ECT) Sensor (On Radiator)G83 before the radiator coolant outlet.

SSP222-023

SSP222-003

SSP222-024

Engine Coolant Temperature (ECT)Sensor G62 (At engine outlet determines coolantactual value 1)

Engine Coolant TemperatureSensor (On Radiator) G83(At radiator outlet determines coolant actualvalue 2)

Coolant circuit shown isfor example only.

G62 G83

J220

SSP222-030

Signal Utilization

Comparison of the specified temperaturesstored in the maps with the coolant actualvalue 1 temperature gives the pulse-width-modulated signal for the application ofvoltage to the heating resistor in the MapControlled Engine Cooling Thermostat F265.

Comparison of the coolant actual values1 and 2 is the basis for activation ofthe electric Coolant Fan V7 and CoolantFan -2- V177.

Effects of Failure

If Engine Coolant Temperature (ECT)Sensor G62 fails, a defined substitute valueof 203F (95C) is used for coolanttemperature control and the first fan speedstays activated.

If Engine Coolant Temperature (ECT)Sensor (On Radiator) G83 fails, the controlfunction remains active and the first fanspeed stays activated.

If a certain temperature threshold isexceeded, the second fan speed isactivated.

If both sensors fail, maximum voltage isapplied to the heating resistor in the MapControlled Engine Cooling Thermostat F265and the second fan speed stays activated.


21

Map Controlled EngineCooling Thermostat F265

The Map Controlled Engine CoolingThermostat F265 is the coolant controlactuator.

A standard expansion-element thermostatwithout the benefit of electric heating isdesigned to regulate engine outlet coolantat a specific temperature. The MapControlled Engine Cooling Thermostat F265sets the coolant temperature at a design-defined point in much the same way, butthe defined set point can be changed tomeet the cooling needs of the engine usingthe available control maps.

A heating resistor is integrated into thewax thermocouple expansion element ofthe Map Controlled Engine CoolingThermostat F265.

Without the application of voltage to theheating resistor, the surrounding coolanttemperature causes the wax in theexpansion element to liquefy and expandat 230F (110C).

With an application of voltage, the heatingresistor heats the wax above thetemperature of the surrounding coolant.The heating wax expands causing the liftingpin to extend in accordance with the map(stroke X in the illustration). The positionsof the coolant thermostat large and smallvalve discs are mechanically adjusted bythe movement of the lifting pin.

The purpose of the thermostatheating system is not to heat thecoolant. It heats the expansionelement in a controlled manner inorder to open the large coolingcircuit.

x

Wax Thermocouple

Lifting Pin

HeatingResistor

SSP222-006

Map Controlled Engine CoolingThermostat F265


22


23

Thermostat heating resistor heating iscontrolled by the Motronic Engine ControlModule J220 in accordance with the mapby a pulse-width-modulated (PWM) signal.

The extent of heating varies depending onpulse width and time.

No voltage is applied when thevehicle is at rest with the engineidling or during the enginestarting cycle.

Rule:

PWM low (without voltage) =high coolant temperature

PWM high (with voltage) =low coolant temperature

Effects of Failure

If there is no operating voltage present:

Thermostat control takes place only bymeans of the wax thermocoupleexpansion element.

The first fan speed is continuouslyactivated.

J220 Motronic Engine Control ModuleJ293 Coolant Fan Control Module

V7 Coolant FanV177 Coolant Fan -2-

J293

3131

V7

M

V177

M

J220

SSP222-025


24

Coolant Fan V7 andCoolant Fan -2- V177

The full-throttle low coolant temperaturemode makes heavy demands on thecooling system.To increase its cooling capacity, theMotronic Engine Control Module J220 caninitiate one of two speed settings forCoolant Fan V7 and Coolant Fan -2- V177.Fan control is based on the differencebetween the coolant temperaturesmeasured at the engine outlet and at theradiator outlet.The Motronic Engine Control Module J220stores the control conditions for the fans intwo maps: Temperature difference for fan, first

speed. Temperature difference for fan, second

speed.Both maps are similar to the oneshown here, and both are dependent onengine load (intake air mass) and enginespeed (rpm).There are three fan operating modes: Off. On, first speed. On, second speed.

Run-On

Run-on of Coolant Fan V7 and CoolantFan -2- V177 after the engine is turned offis time and temperature dependent.

Effects of Failure

If a fault occurs in the circuit for the first fanoutput stage, the second stage is activated.If a fault occurs in the circuit for second fanoutput stage, the Map Controlled EngineCooling Thermostat F265 is fully energizedas a safety precaution.

SSP222-026

Engine Load (Intake Air Mass)

Tem

pera

ture

Diff

eren

ce

Engine Speed

Map 1 Temperature Difference forFan First Speed

Electrical Circuit Compenents

25

Fuel Supply 1.8T

Pressure-Regulated Fuel Filter

For the 1.8T engine, the fuel supply isrouted through a pressure-regulated filter.This new design eliminates the need for afuel return line from the engine fuel rail.Fuel in the tank is pressurized by the in-tankfuel pump and supplied through port VLto the filter. The pressurized fuel fills thechamber, flowing through the paper filterelement and out through the port labeledMOTOR to supply the engine fuel rail.

If the fuel pressure in the filter exceeds thefilter pressure regulator threshold, theregulator valve opens and routes fuelthrough the plastic center tube and out atport RL to return to the tank.Fuel filter port E vents the pressureregulator to atmospheric pressure throughthe evaporative emission (EVAP) canister.

When the pressure-regulatedfuel filter is installed, the arrowsprinted on the filter must point inthe direction of fuel flow.

78500005

EvaporativeEmission(EVAP)Canister

PressureRegulator

Filter PressureRegulator Ventto EVAP Canister

Port E

Engine

Fuel Supplyto Engine

PortMOTOR

Fuel Filter

Tank Vent toEVAP Canister

Port RL

Fuel Returnto Tank

Port VL

Fuel Supplyfrom Tank

Fuel Tank

Exhaust Flap 3.0-Liter V6

Front-wheel drive vehicles equipped with3.0L V6 engines have an exhaust flapinstalled at one of the rear silencer outlets.This design ensures that legal restrictionson noise are met at engine idle and lowengine speeds.

78500006

Cross Section A

78500007

A

Exhaust Flap

26

Exhaust System Exhaust Flap


27

Exhaust Flap Operation

Exhaust flap operation is controlled by theMotronic Engine Control Module J220.When vehicle speed is above 3.1 mph(5 km/h) and engine speed is above2000 rpm, there is no signal to the Valvefor Exhaust Flap N220 and the flap is opento allow maximum flow of exhaust gases.

When vehicle speed is below 3.1 mph(5 km/h) or the engine speed drops below1800 rpm, the Motronic Engine ControlModule J220 sends a signal to activate theValve for Exhaust Flap N220 and the flap isclosed to reduce exhaust noise to anacceptable level.

Effect of Failure

In the event of exhaust flap system failure,the default position is with the flap open.

Open

Closed

6500

6000

5500

5000

4500

4000

3500

3000

2500

2000

1500

1000

500

0

0 50 100 150 200 250 km/h0 31 62 93 124 155 mph

Vehicle Speed

En

gin

e S

pee

d (

RP

M)

3.1 mph(5 km/h)

Acceleration Deceleration

78500008

3.0 V6 220 hp (162 kW)Switching Diagram of the Exhaust Flap

78500009

Atmospheric Pressure

Vacuum

The system applies vacuumand the flap is closed.

MotronicEngine ControlModule J220

Valve forExhaust FlapN220

VacuumCheck Valve

IntakeManifold

Flap is open.

OtherConsumers

VacuumReservoir

ExhaustFlap Open

OtherConsumers

ExhaustFlap Closed


MotronicEngine ControlModule J220

VacuumCheck Valve

IntakeManifold

VacuumReservoir


28


29

Exhaust Flap VacuumSystem Overview

78500010

Vacuum Unit for IntakeManifold Change-Over

Change-Over Valve forIntake Manifold Flap N239


Secondary AirInjection (AIR)Solenoid ValveN112

EvaporativeEmission (EVAP)Canister PurgeRegulator ValveN80

DiagnosticsPump forFuel System

Exhaust Flap

Combination Valvefor SecondaryAir Injection

BrakeBooster

SuctionJet Pump

VacuumCheckValve

EvaporativeEmission(EVAP)CharcoalCanister

FuelDistributionRail withPressureControl Valve

VacuumReservoir

VacuumReservoir

Combination Valvefor SecondaryAir Injection

Exhaust FlapFunctional Diagram

Components

G6 Fuel PumpG21 SpeedometerG22 Speedometer Vehicle Speed Sensor (VSS)G28 Engine Speed (RPM) SensorG186 Throttle Drive (Power Accelerator Actuation)G187 Angle Sensor 1 for Throttle DriveG188 Angle Sensor 2 for Throttle Drive

S3415A

J271

S2820A

96

M

N220

15

31

30

CAN-H

CAN-L

G188G187G186

+-J338

M

J220

G28

J218 G21

G22

In Out

S710A

J218 Instrument Cluster Combination ProcessorJ220 Motronic Engine Control ModuleJ271 Motronic Engine Control Module Power

Supply Relay

N220 Valve for Exhaust Flap

S7 FuseS28 Fog Light FuseS34 Terminal 50 Fuse

78500011


30

Suspension Pneumatic Damping Control

31

Pneumatic Damping ControlShock Absorbers

Rear Axle Variable LoadRecognition System

The Audi allroad quattro four-level airsuspension employs a continuously variableload recognition system at the rear axle.This system enhances vehicle handling bymaintaining suspension damping at aconstant level whether the vehicle ispartially or fully loaded.

The use of air springs in combination withthe natural vibration frequency of the bodystructure maintains virtually constantvibration characteristics regardless of theload on the system.

The system adjusts to provide acomfortable ride with a light load andsufficiently firm damping under a heavyload.

The pneumatic damping control (PDC)shock absorbers provide this capability. InPDC shock absorbers, the damping force isvaried as a direct result of the amount of airpressure present in the air springs at anygiven moment.

SSP242/043

Hose

Coaxial Arrangement ofAir Spring and PDC Shock Absorber

SSP242/057

1.0 1.2 1.4Body Weight Ratio

Deg

ree

of D

ampi

ng

PDC Shock Absorbers Conventional Shock Absorers

1.6 1.8 2.0

Air Spring

PDC Valve

The damping force is altered by a PDCvalve integrated into the shock absorber.The PDC valve is connected to air spring airchamber pressure by a pneumatic hose.

A variable throttle valve in the PDC valve iscontrolled by the internal air pressure in theair spring. This provides a continuouslyvariable control of damping in directproportion to the load on the suspensionsystem. The movement of the throttlevalve changes the resistance to hydraulicfluid flow in the shock absorber and thusthe damping force during both compressionand rebound.

The air connector in the PDC valve includesa restricting orifice between the air springside and the valve piston side. This airrestriction reduces the influence of thedynamic pressure changes in the air springon the shock absorber during compressionand rebound.

SSP242/042

SSP242/087

Separate Arrangement of Air Springand PDC Shock Absorber

00 0.43 0.85 1.28 1.71 2.13 2.56 2.99 3.41 ft/s

0 0.13 0.26 0.39 0.52 0.65 0.78 0.91 1.04 m/s

0

200

400

600

800

1000

1200

1400

1600

45

90

135

180

225

270

315

360Nlb

Piston Speed

Compression

Rebound

Dam

ping

For

ce

138 psi (950 kPa)116 psi (800 kPa)94 psi (650 kPa)

Air SpringHose PDC Valve


32


33

Design and Function

The PDC valve affects the resistance tohydraulic fluid flow in the working cylinderon the piston rod side.

The hydraulic fluid in the piston rod side ofthe working cylinder is routed to the PDCvalve through holes in the side of thecylinder near the top and a jacket thatencases the cylinder. The flow resistance ofthe PDC valve is directly proportional to theair spring air pressure. The PDC valve has alow flow resistance when the air spring airpressure is relatively low; when the vehicleis lightly loaded. Some of the hydraulic fluidgets past the PDC valve throttle valve,effectively reducing the damping force inthe shock absorber.

The total damping force in the shockabsorber for compression or rebounddamping is determined by the flowresistance of the piston valve, the bottomvalve, and the PDC valve.

SSP242/033

Working Cylinder

Piston Valvewith SealingCollar

Holes

GasCharge

Bottom ValveThrottleValve

PDCValve

RestrictingOrifice inAir Connector

PistonRod Sideof WorkingCylinder Rebound

Stop

CylinderJacket

Function during compressionat low air spring air pressure

During compression, the piston is pusheddownward in the shock absorber workingcylinder. Some of the hydraulic fluid flow isthrough the piston valve. Most of the fluidflows through the bottom valve, with aproportional amount flowing through theopen PDC valve, the cylinder jacket, andthrough the holes in the side of the cylinderinto the cylinder behind the moving piston.Since the air spring air pressure is low, theflow resistance at the PDC valve is low.More fluid can get past the PDC valve andthe damping force is reduced.

Function during compressionat high air spring pressure

Since the controlling air spring air pressureis high, the flow resistance at the PDCvalve is high. Depending upon the controlpressure, little or no fluid gets past the PDCvalve. Most of the fluid must flow throughthe piston valve, and the damping force isincreased.

Low Air SpringAir Pressure

PDC Valve Closed

SSP242/069

SSP242/070

PDC Valve Open

High Air SpringAir Pressure

34


35


Low Air SpringAir Pressure

SSP242/051

High Air SpringAir Pressure

SSP242/052

PDC Valve Open

PDC Valve Closed

Function during reboundat low air spring air pressure

During rebound, the piston is drawnupward. Part of the fluid flows through thepiston valve, some flows through thebottom valve, and the rest flows throughthe holes in the side of the cylinder andthrough the cylinder jacket to the PDCvalve. Since the air spring air pressure islow, the flow resistance at the PDC valve islow. More fluid can get past the PDC valveand the damping force is reduced.

Function during reboundat high air spring air pressure

Since the air spring air pressure is high, theflow resistance at the PDC valve is high.Depending upon the control pressure, littleor no fluid gets past the PDC valve. Most ofthe fluid must flow through the pistonvalve, and the damping force is increased.

The Tire PressureMonitoring System

The tire pressure monitoring system usedby Audi is a four-wheel system. Althoughthe spare wheel is monitored andmanaged by the Tire Pressure MonitoringControl Module J502, it is excluded fromthe system status messages. (For furtherdetails, refer to Spare Wheel.)Data transfer from the sensors at eachwheel to the Tire Pressure MonitoringControl Module J502 is by radio-frequency(RF) transmission. Information exchangebetween the peripheral components in thevehicle takes place via the convenienceCAN data bus.A measuring and transmitter modulemounted on the tire valve sends a radiosignal at regular time intervals to theantenna for tire pressure monitoringintegrated in the wheel housing. This signalis then relayed to the Tire PressureMonitoring Control Module J502.The Tire Pressure Monitoring ControlModule J502 evaluates the tire pressuresand any pressure changes and sendscorresponding system status messages tothe Instrument Cluster CombinationProcessor J218. These messages areindicated to the driver on the display of theDriver Information System (DIS).The tire pressure monitoring system offersthe following advantages: Increased safety through early low tire

pressure warnings. More convenience through the

elimination of regular tire pressuremonitoring. The tire pressure need onlybe corrected when this is indicated.

SSP219/012

Longer service life of tires. A pressuredeficit of 4.4 psi (30 kPa) can reduce theservice life of tires by up to 25%.

Lower fuel consumption through correcttire pressure.

36

Tires Tire Pressure Monitoring

Tire pressure monitoring differentiatesbetween the following situations: Slow loss of pressure. Sudden loss of pressure. Flat tire when the vehicle is stationary.A slow loss of pressure is indicated to thedriver at an early stage so the driver cancheck the tires or correct the tire pressure.If a sudden loss of pressure occurs(blowout, flat tire) while travelling, thedriver is alerted immediately. The driver willnormally notice this anyway by the way thevehicle reacts.The tire pressure monitoring systemindicates the loss of pressure to the driverat an early stage so that he or she can takeappropriate action.The system indicates a flat tire when thevehicle is stationary to the driver directlyafter turning on the ignition.

37


System Components

Vehicle Overview

The tire pressure monitoring systemincludes the following components:

Five tire pressure sensors Four Antennas for Tire Pressure Check

Sensor forTire Pressure,Rear Right G225

MENUE

RETURN

INFO

Antenna forTire PressureCheck, RearRight R62

Function SelectorSwitch II E272

Instrument ClusterCombinationProcessor J218

Tire PressureMonitoring ControlModule J502

Sensor forTire Pressure,Front RightG223

SSP219/026

Antenna forTire PressureCheck, FrontRight R60

Sensor forTire Pressure,Spare Tire G226

Antenna forTire PressureCheck,Rear Left R61

Sensor forTire Pressure,Rear Left G224

Antenna for TirePressure Check,Front Left R59

Sensor forTire Pressure,Front Left G222

Tire Pressure Monitoring ControlModule J502

Instrument Cluster CombinationProcessor J218

Function Selector Switch II E272

Metal Tire Inflation Valves

The tire inflation valves have beenredesigned for use with the tire pressuremonitoring system. Metal valves arenow used in place of the rubber valvesused previously.

Metal valve bodies are reusable. Wheninstalling a new tire on a used rim, only thevalve insert need be replaced (refer toRepair Manual).

38


SSP219/030

Metal Valve Body

Sealing Ring

Valve InsertPlain Washer

Cap Nut

Cap

SSP219/008

39


Sensors for Tire Pressure:Front Left G222Front Right G223Rear Left G224Rear Right G225Spare Tire G226

The Sensors for Tire Pressure are attachedto the metal tire inflation valves by screwsand can be reused after replacing the tiresor wheels.

The following components are integrated ineach Sensor for Tire Pressure:

Transmitter antenna. Pressure sensor. Temperature sensor. Measuring and control electronics. Battery.

The pressure sensor, temperature sensor,and measuring and control electronicsintegrated into each, result in anintelligent sensor.

The pressure sensor records themomentary tire pressure (absolute pressuremeasurement) and sends the measureddata to the Tire Pressure Monitoring ControlModule J502 for evaluation purposes.

The temperature sensor has twofunctions:

To compensate for the temperature-dependent changes in tire pressure.

For diagnostic purposes.

If a defined temperature threshold isexceeded, the temperature sensor stopsradio transmission. (For further details, referto Temperature Cut-Out.)

Temperature compensation is controlledby the Tire Pressure Monitoring ControlModule J502. The measured tire pressuresare normalized to a temperature of68F (20C).

Sensor forTire Pressure

Front Left G222Front Right G223Rear Left G224Rear Right G225Spare Tire G226

Metal Valve Body

SSP219/009

SSP219/029

Depending upon the vehicle marketingarea, two different carrier frequencies areused for radio transmission: The carrier frequency of 433 MHz is

permitted in most countries. A 315 MHz carrier frequency is used in

the United States and Canada and in afew other countries.

The carrier frequency is printed on thesensors, antennas and control units. It canalso be identified by the part number.The tire pressure monitoring system onlyworks with system components with thesame carrier frequency.The air pressure in a closed systemchanges in proportion to temperature.In normal circumstances, a temperaturechange of 18F (10C) results in a pressurechange of 1.45 psi (10 kPa).

To avoid inaccurate settings,special care must be taken toensure that the tire pressures arechecked, corrected, and storedwhen the tires are cold.

40


Explanatory notes:

Atmospheric pressure is the term used todescribe the air pressure at the earthssurface. At mean sea level, this pressureaverages about 14.7 psi (101.3 kPa), alsocommonly referred to as 1 atmosphere or1 bar for practical applications (moreprecisely, 1 bar is equivalent to 0.98697atmosphere, or 14.51 psi (100kPa)).Relative pressure indicates a pressureusing atmospheric pressure as thestarting point.Absolute pressure is the pressure usingzero pressure as the starting point.

41


SSP219/011

SSP219/046

The transmitter antenna of each Sensorfor Tire Pressure sends the followinginformation:

Individual ID number (ID code).

Momentary tire pressure(absolute pressure).

Momentary tire air temperature.

Condition of integrated battery.

Status, synchronization, andcontrol information required for safedata transfer.

This information is contained in a datamessage 12 bytes in length. The datatransfer is frequency-modulated and thetransfer time is approximately 10 ms.

Each tire pressure sensor has anindividual ID number (ID code)which is used for the purpose ofown wheel recognition.

You can find more information inthe descriptions of the TirePressure Monitoring ControlModule J502, and Own WheelRecognition.

Temperature cut-out

Electronic components aresensitive to high temperature.This can cause components tomalfunction or fail.

In order to avoid generating erroneousinformation, no further radio signals (datamessages) are sent when the Sensor forTire Pressure registers a temperature ofapproximately 248F (120C).

Shortly before the Sensor for Tire Pressureturns off the transmitting electronics, theTire Pressure Monitoring Control ModuleJ502 is informed that a temperature cut-out is imminent. A fault message to thiseffect is then stored in the fault memory.

If the temperature drops below adefined limit, the sensor will again enterradio mode.

If a temperature cut-out is activated for oneor more sensors, the yellow messagesymbol appears.

The power supply to theSensors for Tire Pressure

The measuring, control and transmittingelectronics in the Sensors for Tire Pressurereceive their power supply from anintegrated lithium battery.

To prolong the service life of the Sensorsfor Tire Pressure for as long as possible, thecontrol electronics include an ingeniousenergy management system.

42


SSP219/045

6

730

5040

20SSP219/040

43


The energy management system

Relatively few measured-datatransmissions are needed for the tirepressure measurements. However, a lossof pressure must be detected immediatelyand indicated to the Tire PressureMonitoring Control Module J502.

The energy management system candifferentiate between the normal transfermode and the high-speed transfer mode,because there are differing measuring andtransfer intervals for each mode.

When the tire pressure readings areconstant, the Sensors for Tire Pressure arein normal transfer mode.

If a loss of pressure of more than 2.9 psi(20 kPa) per minute occurs, the Sensor forTire Pressure immediately is switched to ahigh-speed transfer mode.

In this way, the energy managementsystem keeps the load on the sensorbattery as small as possible and ensureshigh-reliability monitoring at the same time.

A theoretical battery service life of up to 7years is therefore possible.

The batteries are an integralpart of the Sensors for TirePressure. When a sensorbattery looses its charge, thesensor must be replaced.

The theoretical battery servicelife can be interrogated usingthe self-diagnosis (refer to theRepair Manual).

SSP219/010

SSP219/018

NormalTransfer Mode

High-SpeedTransfer Mode

MeasuringInterval

TransferInterval

3.5 Seconds

0.8 Second

55 Seconds

Time

Time

Approximately 7 Years

Time (Years)

Volta

ge (V

)

Antennas for Tire Pressure Check:Front Left R59Front Right R60Rear Left R61Rear Right R62

The Antennas for Tire Pressure Checkreceive the radio signals from the Sensorsfor Tire Pressure and transfer them to theTire Pressure Monitoring Control ModuleJ502 for further processing.

The tire pressure monitoring system usesfour Antennas for Tire Pressure Checkwhich are installed in the wheel housings atthe front left, front right, rear left and rearright behind the wheel housing liners.They are connected to the Tire PressureMonitoring Control Module J502 byshielded high-frequency antenna wires inaccordance with their installed locations.

The antennas receive all the radio signalswithin their reception range and frequencyband. Each antenna receives the radiosignals from all the Sensors for TirePressure located in its range.

The radio signals are filtered and selected inthe Tire Pressure Monitoring ControlModule J502 to ensure that the correctdata are processed.

The tire pressure monitoringsystem only works with systemcomponents which have thesame carrier frequency (refer toSensors for Tire Pressure). Thecarrier frequency is printed onthe antennas and can also beidentified by the part number.

There is no separate antennafor the spare wheel (refer toSpare Wheel).

44


SSP219/011

SSP219/016

45


To avoid interference with thetransmission of signals, defectiveantenna wiring must not berepaired while a high frequencytransmission is in progress!

If an antenna wire is damaged,the cable set must be replaced.

Self-diagnosis

The Antennas for Tire Pressure Check arecurrently not monitored by the self-diagnosis. If no signal is recorded in thefault memory for a Sensor for Tire Pressure,either the antenna or the antenna wiring forthat sensor may be affected. A provisionhas been made for antenna diagnosis at alater date. You will find informationregarding this in the relevant Repair Manualwhen it becomes available.

Tire Pressure MonitoringControl Module J502

The Tire Pressure Monitoring ControlModule J502 evaluates the radio signalsfrom the Antennas for Tire Pressure Check,

prioritizes these signals and transfers therelevant information to the instrumentcluster. Where corresponding relevantwarnings are issued by the driverinformation system (DIS) display.

If Save pressures! is activated,the Tire Pressure MonitoringControl Module J502 is asked notonly to store the new tirepressures but also to readapt tothe previously stored sensors andtheir positions. You will find moredetailed information under OwnWheel Recognition.

Communication with the peripheral tirepressure monitoring components in thevehicle takes place via the convenienceCAN data bus. The system statusmessages are prioritized by evaluatingdifferent limit values, as well as thepressure drop, as a function of time (thepressure drop gradient).

SSP219/013

46

For this purpose, two independently storedtire pressures are saved to the TirePressure Monitoring Control Module J502:

The first of these are the encoded tirepressures for the partly loaded conditionand the fully loaded condition programmedinto the Tire Pressure Monitoring ControlModule J502 (refer to Repair Manualfor more information about encodingthe module).

These pressures refer to the data on thesticker affixed to the fuel filler door and areentered with the help of the coding table. Alower pressure limit is calculated using thepressure for the partly loaded (condition)as the starting point (refer to description ofsystem messages).

The second tire pressure stored is set bythe driver using the menu item Savepressures! on the Driver InformationSystem (DIS) display (refer to the vehicleOwners Manual).

Using the DIS menu, the driver can storehis individual tire pressures (e.g. for fullyloaded condition or winter tires).

The pressures stored using themenu have priority over theencoded tire pressures unlessthey are set below the encodedlower pressure limit.


Example:

Coding 2 0 3 2 9

(1bar is equivalent to 0.98697 atmosphere, or14.51 psi (100kPa))

2.2 bar(31.9 psi(220 kPa))partly loadedcondition

2.9 bar(42.1 psi(290 kPa))fully loadedcondition

47

System Functions

Operation

The tire pressure monitoring system can beturned off and on with the Function SelectorSwitch II E272. The current tire pressures canbe stored in the Tire pressure submenu.

Storing the tire pressures

Check, correct, and store the tirepressures when the tires are coldto avoid inaccurate settings.

Check and correct the inflation ofall the tires on the vehicle at thesame time using the same tiregauge and air supply.

Execute the Save pressures!function from the DIS menu afterchecking or correcting the tirepressures to avoid generatingfaulty signals.

Ignoring these precautions and monitoringor correcting the tire pressures of differenttires using a different air supply or tiregauge will lead to premature or delayedsystem status messages depending uponthe differences in the temperature andquality of the air supply and the tolerancesof the tire gauges.

This also applies if the tire pressures arecorrected when their temperatures aredifferent (such as when including the sparein the tire rotation sequence), or if sometire pressures are corrected at differentambient temperatures than others (some insummer and others in winter), and thepressures are not stored each timepressure corrections are made.

The desired menu option can be selectedwith the rotary switch/pushbutton of theFunction Selector Switch II E272 (refer tooperating instructions).


MENU

RETURN

INFO

6

730

5040

20

SSP219/007

Display mode

Menu OFFInterrogate

Set

Help

Settings

ComputerClock

Tire pressureRadio displaySpeed warning

BACK

Tire pressure

3 ON

o Save

Pressures!

Back

Tire pressure

The momentarytire pressureshave beenstored

Back

48


Turning the system off and on

The system can be turned off and on by thedriver using the DIS menu. The yellowstatus message symbol for tire pressuremonitoring system off is displayed brieflywhenever the ignition is turned on and thesystem is off.

6

730

5040

20SSP219/038

OFF

Status Messages

System status messages are divided intotwo priority levels depending on their effecton vehicle handling and performance.Priority 1 messages have highsignificance and are intended for systemstates in which driving safety is no longerassured. Priority 1 status messages areindicated by red warning symbols on theDIS display and by acoustic chime signals.The driver is asked to check the conditionof the tires immediately.Priority 2 messages have lowsignificance and are intended for systemstates which are non-critical with regard todriving safety. The driver is informed aboutthe condition of the system by yellowsymbols on the DIS display.As a rule, priority 1 and 2 statusmessages are each further subdividedinto two categories: no position andposition-related.No position means that the systemcannot give exact information regarding thefault location, or that there are several faultlocations which lead to the status messageno position.Position-related means that the systemcan determine the fault location exactly andonly this location can be responsible forcausing the fault.Priority 1 Messages

are displayed under the following conditions: The actual tire pressure drops below

alarm threshold 2. The actual tire pressure drops below

alarm threshold 3. The pressure loss gradient is greater than

0.2 bar per minute (2.9 psi per minute(20 kPa per minute)).

Whenever Save pressures! is executed,the tire pressure monitoring system isturned on automatically.

49


Priority 1 messages aredisplayed immediately after anevaluation has been made bythe system.

A priority 1 message isalways displayed as fromalarm threshold 3!

Specified tire pressure stored using theDIS menu.

Actual tire pressure.

Alarm threshold 1 . . . . . . is 0.2 bar (2.9 psi (20 kPa)) below thespecified tire pressure stored using theDIS menu.


20 4 6 8 10 12 14

SSP219/021

Pre

ssu

re

2 bar(29.02 psi(200 kPa))

1 bar(14.51 psi(100 kPa))

Time in Seconds

Case 2Rapid pressure loss gradient > 0.2 bar/min (2.9 psi/min(20 kPa/min)), [Tire pressure loss gradient in the example is0.4 bar/min (5.80 psi/min (40 kPa/min)).]

Case 1Sudden rapid pressure loss.

2.3 bar (33.37 psi (230 kPa))

2.1 bar (30.47 psi (210 kPa))

1.9 bar (27.57 psi (190 kPa))

1.7 bar (24.67 psi (170 kPa))

Alarm threshold 3 . . .. . . is the lower pressure limit calculatedfrom the encoded tire pressure for thepartly loaded condition.

For example, according to the codingtable for an Audi A8 under partial load, thelower pressure limit is 1.7 bar (24.67 psi(170 kPa)) at a specified inflation pressureof 2.2 bar (31.91 psi (220 kPa)).

Color Coding

Rapid loss of pressure priority 1

50


The following priority 1messages can be displayed:

This priority 1, no position status messageappears when at least one of the conditionsfor priority 1 is fulfilled and a definite wheelposition cannot be assigned.

One or more wheels may be affected.

This status message may also pertain tothe spare wheel in certain conditions (formore detailed information, please refer toSpare Wheel).

6

730

5040

20

Check

tire pressure

SSP219/031

This priority 1, position-related statusmessage includes the wheel position of thefault as determined by the system.

6

730

5040

20

Tire pressure,

front left

Tire pressure,

front right

Tire pressure,

rear left

Tire pressure,

rear right

SSP219/032

51


This message is displayed when theCheck key is pressed while a priority 1status message is indicated.

If the navigation system is active, allpriority 1 messages are indicated by thissmaller symbol at the top of the DIS displayafter an initial short-term full-screen displayso that route guidance can continue.

The priority 1 messages are cancelled if:

all Sensors for Tire Pressure receive atire pressure over alarm threshold 1 0.2 bar (2.9 psi (20 kPa)) under the storedspecified tire pressure, and

the tire pressures are stored again usingthe DIS menu.

6

730

5040

20

Check tirepressures

SSP219/033

6

730

5040

20SSP219/034

52

Slow loss of pressure priority 1,wrong pressure setting storedusing the DIS menu


SSP219/022

Color Coding



Alarm threshold 3 . . . . . . is the lower pressure limit calculatedfrom the encoded tire pressure for thepartly loaded condition.

For example, according to the codingtable for an Audi A8 under partial load, thelower pressure limit is 1.7 bar(24.67 psi (170 kPa)) at a specified inflationpressure of 2.2 bar (31.91 psi (220 kPa)).

X X X0

Normal lossof pressure(through diffusion)

1.9 bar (27.57 psi (190 kPa))

Filling Filling

Pre

ssu

re

Time in Months

2 bar(29.02 psi(200 kPa))

1 bar(14.51 psi(100 kPa))

1.7 bar (24.67 psi (170 kPa))

A priority 1 message isalways displayed as fromalarm threshold 3!

This diagram shows a wrong pressuresetting stored using the DIS menu. Alarmthreshold 3 is established by the encodedtire pressure for the partly loaded condition.In this example, a priority 1 message isdisplayed when the tire pressure dropsbelow the lower pressure limit of 1.7 bar(24.67 psi (170 kPa)).

53


Priority 2 Messages

are displayed under any of the followingconditions:

The actual tire pressure drops belowalarm threshold 1.

The pressure differential at the wheelson the same axle is greater than 0.4 bar(5.80 psi (40 kPa)).




Alarm threshold 2 . . .. . . is 0.4 bar (5.80 psi (40 kPa)) below thespecified tire pressure stored using theDIS menu.

Slow loss of pressure priority 2

The system is turned off or unavailabledue to faults.

If position recognition has notbeen performed by the system,no priority 2 messagesregistering actual pressure dropor pressure differential will bedisplayed.

Alarm threshold 3 . . .. . . is the lower pressure limit calculatedfrom the encoded tire pressure for thepartly loaded condition.

For example, according to the codingtable for an Audi A8 under partial load, thelower pressure limit is 1.7 bar (24.67 psi(170 kPa)) at a specified inflation pressureof 2.2 bar (31.91 psi (220 kPa)).

X0 X XTime in Months

Normal lossof pressure(through diffusion)

Pre

ssu

re 2.3 bar (33.37 psi (230 kPa))

2.1 bar (30.47 psi (210 kPa))

1.9 bar (27.57 psi (190 kPa))

1.7 bar (24.67 psi (170 kPa))

Filling Filling

SSP219/020

2 bar(29.02 psi(200 kPa))

1 bar(14.51 psi(100 kPa))

Color Coding

54

Priority 2 messages displayedwhen the actual tire pressure dropsbelow alarm threshold 1

These messages are displayed when theactual tire pressure in a wheel is 0.2 bar(2.9 psi (20 kPa)) less than the specified tirepressure stored using the DIS menu (alarmthreshold 1).

At the same time, the Tire PressureMonitoring Control Module J502 mustknow the positions of the Sensors for TirePressure (priority 2, position-related).

In addition, a difference of more than0.1 bar (1.45 psi (10 kPa)) between actualtire pressure and the stored specified tirepressure must not be received from any ofthe other three Sensors for Tire Pressure.


6

730

5040

20

6

730

5040

20

Front left

Front right

Rear left

Rear right

Front left Front right

Rear left Rear right

SSP219/035

SSP219/036

If a wheel reaches alarm threshold 1 and ifone or more of the other wheels is 0.1 bar(1.45 psi (10 kPa)) below the storedspecified tire pressure, the DIS displays theyellow status message symbol and all fourpositions. No single position is isolated asthe location of the fault.

In this way, the driver is prompted to checkthe tire pressures of all the wheels andcorrect them as needed.

This ensures optimum tire pressuremaintenance and reduces the number ofsystem alarms.

55

Further conditions relatingto actual tire pressure dropsbelow alarm threshold 1

The temperature value transferred by theSensors for Tire Pressure must not be morethan 27F (15 C) above the ambienttemperature when the ignition is turned on.If this temperature threshold is exceeded,the alarm message is suppressed.

The alarm messages concerningactual tire pressure drops belowalarm threshold 1 are notdisplayed until the ignition isturned on again.

The alarm messages concerning actual tirepressure drops below alarm threshold 1 arecancelled if:

a tire pressure which deviates from thestored specified tire pressure by lessthan 0.1 bar (1.45 psi (10 kPa)) isreceived from all Sensors for TirePressure, and

the pressures are stored again using theDIS menu.

Priority 2 messages displayed whenthe pressure differential betweenwheels on the same axle is greaterthan 0.4 bar (5.80 psi (40 kPa))

These messages are displayed whenthe pressure differential betweenthe wheels on an axle (front axle, rear axleor on both axles) is greater than 0.4 bar(5.80 psi (40 kPa)).

This can occur if tire pressure correction isnot performed properly, such as if a wheelhas been omitted from the checking andcorrection routine.

If this happens, the driver must recheckand correct the tire pressures and repeatthe Save pressures! function using theDIS menu.


The alarm messages concerningthe condition that the pressuredifferential between wheels onthe same axle is greater than 0.4bar (5.80 psi (40 kPa)) aredisplayed immediately after theevaluation is performed.

6

730

5040

20

SSP219/037





56

Further conditions relatingto the pressure differentialbetween wheels

The temperature values determined by theSensors for Tire Pressure must not be morethan 54F (30C) above the ambienttemperature. The alarm message issuppressed when this temperaturethreshold is exceeded.

The alarm messages concerning thecondition that the pressure differentialbetween wheels on the same axle isgreater than 0.4 bar (5.80 psi (40 kPa)) arecancelled if the pressures are stored againusing the DIS menu.

Priority 2 messages displayed whenthe system is turned off or unavailabledue to faults

The tire pressure monitoring system canbe deactivated by the driver using theDIS menu.

This is expedient when wheels withSensors for Tire Pressure are transported inthe luggage compartment or when wheelswithout Sensors for Tire Pressure aremounted (winter wheels with snow tiresfor example).

This status message is displayed briefly asinformation for the driver whenever theignition is turned on.


6

730

5040

20SSP219/038

OFF

57

If the system is not available due toradio frequency interference, theseyellow status message symbols willappear on the DIS display.

This can occur when the Antennas for TirePressure Check receive no data messagesdue to interference from electromagneticfields. Possible interference factors includestray ignition shorts to ground (spark plugwire not installed correctly) or the use ofinfrared headphones.

The message is cancelled when the radiofrequency interference is no longer presentand the data messages from the Sensorsfor Tire Pressure have been received.

This message is onlyindicated at vehicleroad speeds greaterthan 3.1 mph (5 km/h).

This yellow status message symbolappears on the DIS display in the event ofother system disturbances, indicating thatthe tire pressure monitoring system is notavailable. (See also Temperature cut-out.)

Examples of other system disturbancesinclude:

Fault in the system such as an opencircuit, defective Tire PressureMonitoring Control Module J502, etc.

No radio signals are received from theSensors for Tire Pressure such asafter installing snow chains or wheelswithout Sensors for Tire Pressure.

The own wheel recognition andposition recognition operations werenot completed by the system within adriving time of 30 minutes.


6

730

5040

20

6

730

5040

20

SSP219/039

SSP219/040

If data messages are received frommore than five Sensors for TirePressure while travelling such asduring the transportation of wheelswith Sensors for Tire Pressure in theluggage compartment.

If the Tire Pressure Monitoring ControlModule J502 has detected an erroneouscode or is not properly encoded.

58

Own Wheel Recognition

Each of the Sensors for Tire Pressure hasits own ID code in the form of a 10-digitnumber. The ID codes are included in thedata messages from the Sensors for TirePressure and are transferred continuouslyto the Tire Pressure Monitoring ControlModule J502.

The Tire Pressure Monitoring ControlModule J502 defines and stores theID codes for the Sensors for Tire Pressurebelonging to the vehicle underspecific conditions.

This process is referred to as own wheelrecognition.

Up to five Sensors for Tire Pressure can bemanaged by the system (including theSensor for Tire Pressure, Spare Tire G226).The ID codes received are comparedcontinuously with the ID codes stored inthe memory, and only the data messagesof the stored sensors are processed.

This ensures that signals from non-systemsensors located within radio receptionrange do not affect the system.

The own wheel recognition system is anadaptive system. The Tire PressureMonitoring Control Module J502 recognizeswhen wheels with different Sensors forTire Pressure are mounted. The newSensors for Tire Pressure are recognizedand stored under specific conditionsthrough algorithmic evaluation.


Sensors for Tire Pressure are only adaptedto the system while the vehicle is moving.This protects the system againstinterference from the tire pressuremonitoring systems of other vehiclesparked in the vicinity, for example.

When the function Savepressures! is invoked fromthe DIS menu, the Tire PressureMonitoring Control Module J502is requested to repeat theown wheel recognition andposition assignment processesin addition to storing the newtire pressures.

Transporting wheels withSensors for Tire Pressure insidethe vehicle is a source of RFinterference and may causethe system to generateerroneous information.

The ID codes of the individualSensors for Tire Pressurecan be displayed under variousdisplay groups with theVehicle Diagnosis, Test andInformation System VAS 5051,using function 08 Readmeasured value block.

59


SSP219/041

List of own wheels (ID code)1 ... 00005781002 ... 00005972003 ... 00005981004 ... 00006023005 ... 0000755100

List of wheel positions (ID code)Left Front ... 0000755100Right Front ... 0000597200Left Rear... 0000602300Right Rear ... 0000578100Spare ... 0000598100

ID codes

MENUE

RETURN

INFO

Tire Pressure Monitoring Control Module J502

0000602300

0000597200

0000755100

0000578100

0000598100

60


Position Recognition

To be able to display position-related alarmmessages to the driver, the Tire PressureMonitoring Control Module J502 mustknow the locations of the Sensors for TirePressure on the vehicle.

Position recognition is an additional functionperformed by the Tire Pressure MonitoringControl Module J502. It assigns theSensors for Tire Pressure automatically andindependently to the installed locations ofthe wheels on the vehicle at the front left,front right, rear left and rear right, as well asthe spare wheel.

This is made possible by the use of fourreceiver Antennas for Tire Pressure Checkand evaluating the reception signals ofvarying strength from the individualSensors for Tire Pressure.

The Tire Pressure Monitoring ControlModule J502 determines the theoreticalpositions of the Sensors for Tire Pressure(installed locations of the wheels at thefront left, front right, rear left and rear right,as well as the spare wheel) usingalgorithmic calculations and statistics.

Because of the many factorsthat can affect signal strengthin radio transmission (e.g.shielding by metal parts,distance from transmitter toantenna, environmentalinfluences etc.), the systemcannot always determinethe position of each Sensorfor Tire Pressure with 100%certainty. Therefore, the termtheoretical position is used.

Monitoring function whenthe vehicle is stationary

To ensure that the monitoring function alsoworks when the vehicle is stationary, theTire Pressure Monitoring Control ModuleJ502 remains active after the ignition hasbeen turned off. The Tire PressureMonitoring Control Module J502 entersenergy-saving mode. It self-activates atregular intervals shortly before the datamessages are transmitted by the Sensorsfor Tire Pressure at each wheel.

This function helps to preserve the vehiclebattery charge and ensures that a flat tire isindicated on the DIS display before thevehicle is moved.

MENUE

RETURN

INFO

0000602300

0000597200

0000755100

0000578100

0000598100

61


Tire Pressure Monitoring Control Module J502

List of own wheels (ID code)1 ... 00005781002 ... 00005972003 ... 00005981004 ... 00006023005 ... 0000755100

List of wheel positions (ID code)Left Front ... 0000755100Right Front ... 0000597200Left Rear... 0000602300Right Rear ... 0000578100Spare ... 0000598100

ID codes

SSP219/042

62

Spare Wheel

The spare wheel has a special status inthe tire pressure monitoring system.It is equipped with a Sensor for TirePressure, Spare Tire G226. Unlike theother wheels, the tire pressure monitoringsystem does not have a separate Antennafor Tire Pressure Check for spare tirepressure monitoring.

The Antennas for Tire Pressure Check ateach of the four wheel housings receivethe data message radio signals from theSensor for Tire Pressure, Spare Tire G226,and send these signals to the Tire PressureMonitoring Control Module J502. The ownwheel and position recognition functionsidentify the fifth wheel as a spare wheel,and it is registered as such in the TirePressure Monitoring Control Module J502.


The tire pressure in the sparewheel can be monitored usingthe Vehicle Diagnosis, Test andInformation System VAS 5051,using Address Word 65,Function 08, Read measuredvalue block, Display group 13.

The prerequisite for this is thatthe position recognition processhas been completed.

This is the case when 015is displayed under Displaygroup 19.

Although the Tire Pressure MonitoringControl Module J502 manages the sparewheel, system alarm messages pertainingto the spare wheel are suppressed andnot indicated.

A priority 1, no position statusmessage may be caused by thespare wheel if the tire inflationpressure is below alarmthreshold 3 and positionrecognition has not yet beenperformed by the system.This could occur after Savepressures! has been initiatedusing the DIS menu or aftera wheel change, but before thevehicle has been driven longenough for the systemto complete the own wheelrecognition and positionassignment processes.

The message is cancelledonce position recognition hasbeen completed by the systemand the spare wheel isrecognized as such.

SSP219/043

63

Convenience CAN Data Bus Interface

Information interchange between theTire Pressure Monitoring Control ModuleJ502 and the vehicle is performed bythe Instrument Cluster CombinationProcessor J218 through the convenienceCAN data bus.

Information received by the Tire PressureMonitoring Control Module J502


3

2

1

45

6

0

710

30

5070 100 140

180

220

260

20

40

60

80

160

200

240

120

1/21/1

R

00 890

C

50 120280

- +

10:0218.01.1999

0.012.345

km

SSP219/025

SSP219/013

Instrument ClusterCombination Processor J218

Ignition onFor requesting that available messages besent immediately, and for the diagnosis ofterminal 15.

Engine speedFor suppressing the voltage diagnosis functionat engine speeds below 500 rpm.

System controlsFor activating the tire pressure monitoringfunction.

Save pressures! requestInitiated by the driver from the DIS menu.

Road speedFor enabling the own wheel recognition andposition recognition functions.

Ambient temperatureFor filtering the messages.

Tire Pressure MonitoringControl Module J502

System activeInformation for the self-diagnosis.

Signal statusFor displaying the various system messages.

System stateAnswer to system conditions.

ConvenienceCAN Data Bus

Information sent by the Tire PressureMonitoring Control Module J502

64

Tire Pressure MonitoringFunctional Diagram


15+

30+

31

G222 G223 G224 G225 G226

TV14

CAN-HIGH

CAN-LOW

S S

J502

R62R61R60R59

INFO

65


SSP219/019

Input Signal

Output Signal

Positive

Ground

Convenience CAN Data Bus

Components

E272 Function Selector Switch IIG222 Sensor for Tire Pressure, Front LeftG223 Sensor for Tire Pressure, Front RightG224 Sensor for Tire Pressure, Rear LeftG225 Sensor for Tire Pressure, Rear RightG226 Sensor for Tire Pressure, Spare TireJ218 Instrument Cluster Combination ProcessorJ502 Tire Pressure Monitoring Control ModuleR59 Antenna for Tire Pressure Check,

Front LeftR60 Antenna for Tire Pressure Check,

Front RightR61 Antenna for Tire Pressure Check,

Rear LeftR62 Antenna for Tire Pressure Check,

Rear RightTV14 Data Link Connector (DLC) Wire ConnectorX Terminal 58s

Gold Contact

Color Codes

3

2

1

45

6

0

710

30

5070 100 140

180

220

260

20

40

60

80

160

200

240

120

1/21/1R0

0 890

C

50 120280

- +

10:0218.01.1999

0.012.345

km

30+

15+

X

S S

J218

E272

0 1

S

MENUE

RETURN

66

Steering Servotronic II

Servotronic II VariableEffort Power Steering

The Servotronic II variable effort powersteering system uses the proven basicsteering valve design and the sameprinciples to vary the steering wheel effort,but incorporates several improvements inthe feedback mechanism over theprevious design.

The basic valve is a rotary steering valvewith a roller bearing encased in asteering box.

The principles used to vary the steeringwheel effort still include active hydraulicfeedback from the feedback mechanism:

Valve resistance increases with vehiclespeed. Therefore, the effort required tomove the steering wheel is increased toenhance straight-line stability at higherspeeds.

Power steering assist to the mechanismat the steering gear is not limited at highvehicle speeds.

Feedback Mechanism

The feedback mechanism converts therotation of the steering valve into axialfeedback piston movement.

The ball screw feedback mechanism usedin t

992203_2002_NewTechnology

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