Brake System Audi TT 8N

Scheme 1

The PR No. on the vehicle data sticker indicates the type of brakes installed in the vehicle.

1. Arrow 1 - Rear brake
2. Arrow 2 - Front brake

The vehicle data sticker is located in the spare wheel recess and in service booklet.

The PR No. can be used to identify the proper brake caliper/brake disc/brake pad combination.

Brakes

General

Wheels are driven by the test stand.

For the test, place shift lever in neutral for vehicles with manual transmission or place selector lever in driving position -N- for vehicles with automatic transmission.

Observe all safety precautions and operating instructions from manufacturer test stand during test.

Front-wheel drive vehicles

Brake test on a 1-axle dynamometer

We recommend a brake test stand with RPM regulation for the rollers and a maximum test speed of 6 Km/h.

Brakes may engage if these specifications are not met (EDL regulation).

If this occurs, switch engine and ignition off for test. To obtain sufficient vacuum for the brake test, let engine run briefly.

All wheel drive vehicles (Haldex clutch)

Brake test on a 1-axle test stand for All Wheel Drive (AWD) vehicles

The wheels on one axle are driven in opposite directions by the test stand so that the other axle is not driven.

We recommend a brake test stand with RPM regulation for the rollers and a maximum test speed of 6 Km/h.

Brakes may engage if these specifications are not met (EDL regulation).

If this occurs, switch engine and ignition off for the test. To obtain sufficient vacuum for the brake test, first let engine run briefly.

If there are no All Wheel Drive (AWD) test stands available, the test can also be performed on a conventional test stand.

1. Drive vehicle forward onto rollers.
2. Switch engine off and wait 2 seconds.
3. Carry out front axle brake test.
4. Start engine and let run for approx. 5 seconds until sufficient vacuum pressure has built up in brake booster.

1. Drive vehicle forward until rear wheels are on rollers.
2. Switch engine off and wait 2 seconds.
3. Carry out rear axle brake test.

Engine must not be running and ignition must not be switched on during test, otherwise the Haldex clutch will drive the rear axle.

General information

Brake fluid is hygroscopic, which means it absorbs moisture from the ambient air and must always be stored in air tight containers.

Scheme 2

An increase in the water content in the brake fluid causes its boiling point to drop. A reduced boiling point can cause vapor bubbles to develop as the fluid heats up under intense braking. In this condition the brake is likely to fail completely.

Brake fluid will take on a darker color after some time. This discoloration is the result of chemical reactions, and is NOT an indication of the fluid losing its properties. The effect appears after a relatively short time (few weeks), on vehicles installed with ABS even faster.

Even very small amounts of the above substances will transform structure and dimension of a sealing ring or sleeve enough to adversely affect brake function. The effects of a polluted brake system will not be noticed for several months until they have caused damage that requires extensive servicing, especially on vehicles installed with ABS.

Scheme 3

A = Sleeve - original size

B = Sleeve - swollen as a result of contact with mineral oil

The above mentioned points require special rules for handling

Always keep containers holding brake fluid tightly shut. Only this will safely keep oil, dirt or detergents as well as moisture in the atmosphere from entering and polluting the brake fluid.

Take extra care to store containers holding brake fluid separate from containers holding oil (including hydraulic fluid) or liquid detergents. This will prevent any chance of accidentally mixing these fluids or even filling the brake system with the wrong fluid.

General notes

Note. Before carrying out repairs to the ABS, determine the cause of the malfunction using On Board Diagnostic (OBD).

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. Only use parts in their original packaging.
2. Only unpack replacement parts immediately prior to installation.
3. Only use lint-free cloths.
4. Thoroughly clean all unions and the adjacent areas before loosening. Do not use aggressive cleaning agents such as brake cleaner, fuel, thinners or similar chemicals.

1. Do not unplug the connector on the hydraulic control unit unless the ignition is switched off.
2. Absolute cleanliness is required when working on the anti-lock brake system. Do not use any products which contain mineral oil, oils, grease and cleaning solvents.
3. Make sure that brake fluid does not enter harness connectors.
4. After finishing any work that required opening the brake hydraulic system, bleed the brake system: ABS/ESP Mark 20. Refer to «ABS/ESP ITT Mark 20, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) , ABS/ESP Mark 60. Refer to «ITT ABS/ESP Mark 60, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) (using brake filler and bleeder unit VAS 5234).

1. When working with brake fluid, observe relevant safety precautions and notes.
2. Place parts that have been removed on a clean surface and cover.
3. Carefully cover over opened components or seal, if repairs are not carried out immediately. (use sealing plugs from repair kit 1 H0 698 311 A)
4. Do not work with compressed air and do not move vehicle while the system is open.

1. When painting, electronic control module can be exposed to a maximum temperature of. 95 ° C only briefly, and to a maximum of 85 ° C for longer periods (approx. 2 hours).
2. Always check control module coding when installing a new hydraulic control unit.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Road test vehicle

1. Some DTCs are only recognized by On Board Diagnostic (OBD) while the vehicle is moving. You can check the system during a road test. During road test, drive at a speed of at least 60 km/h for 30 seconds. Check traffic conditions and perform an ABS regulated braking when appropriate. You will feel a pulsing in the brake pedal indicating the system is active.

Scheme 4

1 - Rotor for right rear ABS wheel speed sensor

1. Rotor is welded to wheel hub.
2. Checking rotor. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) or «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. Removing and installing

Refer to 42 REAR SUSPENSION

2 - Right rear ABS wheel speed sensor -G44

1. Removing and installing. Refer to «Speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__speed-sensor-removing-and-installing) or «Speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

3 - Left rear ABS wheel speed sensor -G46

1. Removing and installing. Refer to «Speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__speed-sensor-removing-and-installing) or «Speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

4 - Rotor for left rear ABS wheel speed sensor

1. Rotor is welded to wheel hub.
2. Checking rotor. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) or «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. Removing and installing

Refer to 42 REAR SUSPENSION

5 - Parking brake indicator light -K14

1. Installed position in instrument cluster

6 - ABS warning light -K47

1. Installed position in instrument cluster

7 - Warning light for brake system -K118-, malfunction symbol

1. Installed position in instrument cluster in Driver Information System (DIS)

8 - Traction control indicator light -K86

1. Installed position in instrument cluster

9 - Brake light disable relay (ESP) -J508

1. Installed position at fuse box
2. Only for vehicles with ESP

10 - Brake light switch -F

1. Removing and installing brake light switch. Refer to «Brake light switch (square housing), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-square-housing-removing) or «Brake light switch (round housing), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-round-housing-removing)

11 - Rotor for left front ABS wheel speed sensor

1. Rotor is welded to wheel hub.
2. Testing. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__rotor-checking)
3. Removing and installing

Refer to 40 FRONT SUSPENSION

12 - Left front ABS wheel speed sensor -G47

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__abs-wheel-speed-sensor-removing-and)

13 - ABS Hydraulic Unit -N55- with ABS control module (w/EDL) -J104

1. The hydraulic control unit consists of the ABS hydraulic pump -V64-, ABS hydraulic unit -N55-, and the ABS control module (w/EDL) -J104-.
2. Removing and installing. Refer to «ABS control module and hydraulic unit, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__abs-control-module-and-hydraulic-unit)

14 - Rotor for right front ABS wheel speed sensor

1. Rotor is welded to wheel hub.
2. Testing. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__rotor-checking)
3. Removing and installing

Refer to 40 FRONT SUSPENSION

15 - Right front ABS wheel speed sensor -G45

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__abs-wheel-speed-sensor-removing-and)

16 - Longitudinal acceleration sensor -G251

1. Only for vehicles with All Wheel Drive (AWD).
2. Installed position: A-pillar on passenger`s side
3. Removing and installing. Refer to «Longitudinal acceleration sensor -G251-, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__longitudinal-acceleration-sensor-g251-removing-and)

17 - Sender -2- for brake booster -G214

1. Removing and installing. Refer to «Brake pressure sensors, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pressure-sensors-removing-and-installing)

18 - Sender -1- for brake booster -G201

1. Removing and installing. Refer to «Brake pressure sensors, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pressure-sensors-removing-and-installing)

19 - Brake pressure release solenoid -F84

1. Brake booster assembly must be replaced if solenoid is defective

20 - Magnetic coil for brake pressure, in brake booster -N247

1. Brake booster assembly must be replaced if solenoid is defective

21 - Brake fluid level warning switch -F34

22 - Sensor for transverse acceleration -G200

1. Removing and installing. Refer to «Sensor for transverse acceleration -G200- and Sender for rotation rate -G202-, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__sensor-for-transverse-acceleration-g200-and)

23 - Sender for rotation rate -G202

1. Removing and installing. Refer to «Sensor for transverse acceleration -G200- and Sender for rotation rate -G202-, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__sensor-for-transverse-acceleration-g200-and)

24 - Anti-Slip control switch -E132

1. Installed position at center console

25 - Steering angle sensor -G85

1. Removing and installing. Refer to «Steering angle sensor -G85-, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__steering-angle-sensor-g85-removing-and)

26 - Parking brake warning light switch -F9

1. Installed position at parking brake assembly

Brake light switch (square housing), removing and installing

Note. To ensure a secure fit, the switch may only be installed once.

Removing

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

1. Unplug electrical connector.

Scheme 5

1. Remove brake light switch -1- by turning counter-clockwise through 90 °.

Installing

Install in reverse sequence; note the following points

1. Pull brake light switch plunger fully out.
2. Press brake pedal down as far as possible by hand.

Scheme 6

1. Guide switch through installation hole and secure by turning 90 ° clockwise -arrows-.
2. Release brake pedal.
3. Make sure proper function of brake lights when brake pedal is pressed and released.

Brake light switch (round housing), removing and installing

Note. To ensure a secure fit, the switch may only be installed once.

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

1. Unplug electrical connector.
2. Remove brake light switch by turning counter-clockwise 45 °.

Install in reverse sequence; note the following points

Scheme 7

1. Pull brake light switch plunger fully out (arrow).
2. Install retainer tabs -1- and -2- on switch into recesses of installation hole and secure by turning clockwise 45 °.

Note. When installing brake light switch, do not operate brake pedal. The plunger is adjusted automatically when the brake light switch is inserted.

1. Make sure proper function of brake lights when brake pedal is pressed and released.

Sensor for transverse acceleration -G200- and Sender for rotation rate -G202-, removing and installing

Work procedure

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

Scheme 8

1. Unplug electrical connectors (arrows) on senders -G200-/-G202-.
2. Remove bolt -1- and remove mounting bracket for senders --G200-/-G202-.

Removing and installing sender for rotation rate -G202

Scheme 9

1. Remove nuts -a- and remove sender for rotation rate -G202- -1-.
2. To install: insert sender for rotation rate -G202- into mounting bracket and align straight before tightening.

Note. The sender for rotation rate is sensitive to shocks or impact. Do not install a sender which has dropped to the ground otherwise proper operation is not ensured.

Removing and installing sensor for transverse acceleration -G200

Scheme 10

1. Use screwdriver to pry mount -1- off sensor for transverse acceleration -G200- -2- and remove sender.
2. To install: insert sensor for transverse acceleration -G200- -1- in holder.

Scheme 11

1. Installation position: sloping side (arrow) of sensor for transverse acceleration -G200- must face mount -2-.

1. Slip mount over sensor for transverse acceleration -G200- until it engages with a click.

Note. The sensor for transverse acceleration is not resistant to shocks or impact. Do not install a sender which has dropped to the ground otherwise proper operation is not ensured.

Installing

The remaining installation steps are carried out in the reverse sequence; note the following points

1. Initiate basic setting for sensor for transverse acceleration -G200- and sender for rotation rate -G202-.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Tightening torques

Longitudinal acceleration sensor -G251-, removing and installing

Removing

1. Remove glove box

Refer to 68 - INTERIOR EQUIPMENT

Scheme 12

1. Unplug electrical connector -2
2. Use a screwdriver to pry mount off longitudinal acceleration sensor -arrows- and remove sensor -G251- -1-.

Note. The longitudinal acceleration sensor is not resistant to shocks or impact. Do not install a sensor which has dropped to the ground otherwise proper operation is not ensured.

Installing

Install in reverse sequence; note the following points

1. Initiate basic setting for longitudinal acceleration sensor -G251-.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Steering angle sensor -G85-, removing and installing

Note. The coil connector with slip ring is enclosed in the housing of the steering angle sensor -G85-.

Removing

1. Turn wheels to straight ahead position.
2. Remove airbag unit and steering wheel.

Refer to 48 STEERING

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

Scheme 13

1. Remove bolts -1- and detach handle for steering column adjustment -5-.
2. Remove bolts -2- to -4-.
3. Remove upper and lower sections of steering column trim.

Scheme 14

1. Disconnect electrical connectors -1- and -2-.

Scheme 15

1. Carefully lift upper retainer tabs (arrows).
2. Carefully lift lower retainer tabs and pull off housing with coil connector, slip ring and steering angle sensor from steering column switch.

Installing

Install in reverse sequence; note the following points

1. Push on housing with coil connector, slip ring and steering angle sensor onto steering column switch until all retainer tabs engage with a click.
2. Break off transportation protection.

Scheme 16

1. Adjust steering angle sensor to center position

1. Yellow dot must be visible in hole (arrow -1-) and the two marks (arrows) must also be aligned.

1. Install airbag unit and steering column.

Refer to 48 STEERING

1. Initiate basic settings for steering angle sensor -G85-.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Brake pressure sensors, removing and installing

Special tools and equipment

Scheme 17

1. Brake filler and bleeder unit VAS 5234

Removing

Scheme 18

1. Remove forward left-hand cover panel (arrows).

Scheme 19

1. If installed, disconnect secondary air intake hose -1- from air cleaner.
2. Disconnect air hose -2- from mass air flow sensor.
3. Unplug connector -3- from mass air flow sensor.
4. Remove bolts -4- and -5-.

1. Remove air cleaner housing.
2. Lay out sufficient lint-free cloths in area below brake master cylinder to catch escaping brake fluid.
3. Draw off as much brake fluid as possible from brake fluid reservoir using brake filler and bleeder unit VAS 5234.

Scheme 20

1. Disconnect connector off relevant pressure sensor (the one to be removed) -arrows-.

a - Sender 1 for brake booster -G201- in primary piston circuit

b - Sensor -2- for brake pressure -G214- in secondary piston circuit

1. Remove brake pressure sensor.

Installing

Install in reverse sequence; note the following points

1. Bleed brake system. Refer to «ABS/ESP ITT Mark 20, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .
2. Bleed hydraulic system for clutch

Refer to 30 CLUTCH for 5 AND 6 SPD. MANUAL TRANSMISSION 02M, 02Y ALL WHEEL DRIVE or 30 CLUTCH for 5 SPD. MANUAL TRANSMISSION 02J FRONT WHEEL DRIVE

1. Initiate basic settings for brake pressure sensors.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Tightening torques

Scheme 21

1 - Self-locking hex nut, 20 Nm

1. Self-locking
2. Replace each time after removing

2 - Bracket

3 - Set bolt, 8 Nm

4 - Cap nut, 20 Nm

5 - ABS hydraulic unit -N55

1. Installed position: in engine compartment, left side
2. Connecting brake lines. See «Brake line connections at hydraulic unit»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

6 - Brake line

1. Master brake cylinder/secondary piston circuit to hydraulic unit

7 - Brake line

1. Brake master cylinder/primary piston circuit to hydraulic control unit

8 - ABS Control Module (w/EDL) -J104

1. Installed position: in engine compartment, left side
2. The control module is bolted to the hydraulic unit

9 - Connection for brake line

1. Hydraulic control unit to left front brake caliper

10 - Connection for brake line

1. Hydraulic control unit to right rear brake caliper

11 - Connection for brake line

1. Hydraulic control unit to left rear brake caliper

12 - Connection for brake line

1. Hydraulic control unit to right front brake caliper

Connection of brake lines from tandem master brake cylinder to hydraulic unit

Scheme 22

A - Secondary piston circuit

B - Primary piston circuit

1 - Hydraulic control unit to right front brake caliper

2 - Hydraulic control unit to left rear brake caliper

3 - Hydraulic control unit to right rear brake caliper

4 - Hydraulic control unit to left front brake caliper

1. After connecting brake lines to hydraulic unit, perform final control diagnosis.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Note. Final control diagnosis can be used to establish whether line connections have been interchanged.

ABS control module and hydraulic unit, removing and installing

Special tools and equipment

Scheme 23

1. Brake pedal depressor VAG 1869/2
2. Repair kit

Scheme 24

1 - Valve dome transportation protection (plastic foam)

2 - M10 sealing plugs for brake lines and threaded holes

3 - M12 sealing plugs for brake lines and threaded holes

After separating the control module from the hydraulic unit always install the valve dome transportation protection on the hydraulic unit.

Warranty claims for hydraulic units on which the valve dome transportation protection was not used, will not be accepted.

Removing

1. Remove screws (arrows).
2. Remove left-hand cover panel forward.

1. If installed, disconnect secondary air intake hose -1- from air cleaner.
2. Disconnect air hose -2- from mass air flow sensor.
3. Disconnect connector -3- from mass air flow sensor.
4. Remove bolts -4- and -5-.

1. Remove air cleaner housing.

Scheme 25

1. Insert brake pedal depressor VAG 1869/2 between brake pedal and driver's seat. Depress the brake pedal by at least 60 mm.
2. Connect hose of bleeder bottle to bleeder screws on left front and left rear brake calipers and open bleeder screws.

Note. This dissipates pressure in hydraulic unit.

1. Close left front and left rear bleeder screws.
2. Do not remove brake pedal depressor VAG 1869/2.

Scheme 26

1. Release control module connector (arrow -1-) and unplug (arrow -2-).

Note. Protect connector housing of control module against escaping brake fluid. Otherwise corroding contacts can cause a breakdown of the system. Carefully clean a moist or dirty connector housing with compressed air.

1. Lay out sufficient lint-free cloths in area below control module and hydraulic unit.
2. Mark brake lines.

Scheme 27

1. Disconnect brake lines from hydraulic unit to brake master cylinder (arrows) and tie up.
2. Disconnect remaining brake lines from hydraulic unit.

1. Seal brake lines and threaded holes with plugs from repair kit.

Scheme 28

1. Remove bolts on hydraulic unit bracket (arrows) and take out hydraulic unit and control module.

Removing control module from hydraulic unit

1. Disconnect connector for hydraulic pump motor from control module.

Scheme 29

1. Unscrew Torx head bolts -arrows- from control module and detach control module.

Scheme 30

1. When detaching control module, make sure valve domes of hydraulic unit do not catch on control module solenoids.
2. Cover control module solenoids with a lint free cloth.
3. Protect components against moisture.
4. Install transportation protection for valve domes (enclosed in repair kit) after separating control module and hydraulic unit.

Installing

Install in reverse sequence; note the following points

Note. Only remove sealing plugs on new hydraulic unit when the corresponding brake line is going to be installed. If the sealing plugs are removed too soon from the hydraulic unit, brake fluid may escape; it may no longer be possible to fill and bleed the unit properly.

1. When assembling control module and hydraulic unit, make sure valve domes of hydraulic unit do not catch on control module solenoids.

1. Connect lines as previously marked

A - Secondary piston circuit

B - Primary piston circuit

1 - To right front brake caliper

2 - To left rear brake caliper

3 - To right rear brake caliper

4 - To left front brake caliper

1. Install connector on hydraulic pump.
2. Bolt ABS control module to bracket.

Note. Do not fully tighten bolts. This facilitates attachment of individual brake lines to hydraulic unit.

1. After tightening brake lines, tighten hydraulic unit.
2. Bleed brake system. Refer to «ABS/ESP ITT Mark 20, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. If a new control module has been installed it must be coded.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. After connecting brake lines to hydraulic unit, perform final control diagnosis.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Note. Final control diagnosis can be used to establish whether line connections have been interchanged.

Tightening torques

1) Replace bolts

2) for M10-connections and M12-connections

Scheme 31

1 - ABS wheel speed sensor

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__abs-wheel-speed-sensor-removing-and)
2. Before installing speed sensor, clean inner surface of hole and coat speed sensor all around with lubricant paste G 000 650
3. Replacing speed sensor wire. Refer to «Wheel speed sensor wire, replacing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__wheel-speed-sensor-wire-replacing)

2 - Wheel bearing housing

3 - Hex socket-head screw 8 Nm

4 - Backing plate

5 - Hex bolt, 10 Nm

1. Tightening torque. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

6 - Wheel bearing

1. Removing and installing

Refer to 40 FRONT SUSPENSION

7 - Phillips-head screw

1. Tightening torque. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

8 - Brake disc

1. Application. Refer to «Application of PR Nos./brakes»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

9 - Wheel hub with rotor

1. Checking rotor. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__rotor-checking)
2. Only replace complete

Refer to 40 FRONT SUSPENSION

10 - Circlip

ABS wheel speed sensor, removing and installing

Removing

Scheme 32

1. Disconnect harness connector -1- from wheel speed sensor wire and wheel speed sensor.
2. Remove bolt -2- from wheel bearing housing.
3. Pull ABS wheel speed sensor out of wheel bearing housing.

Installing

Install in reverse sequence; note the following points

1. Before inserting wheel speed sensor, clean inner surface of bore hole and coat sensor completely with securing grease G 000 650
2. Turn wheels completely to left and right stop positions and check clearance to ABS wheel speed sensor wiring.

Tightening torque

Rotor, checking

1. Raise vehicle.
2. Remove wheel.
3. Check rotor for dirt and damage by rotating brake disc.
4. If rotor is damaged, wheel hub must be removed together with rotor and replaced.

Refer to 40 FRONT SUSPENSION

Checking rotor lateral run-out

Scheme 33

1. Turn wheel hub and check that gap -a- between rotor and speed sensor is uniform.

1. Distance a = 0.3 mm

1. If lateral run-out is out of tolerance, remove and replace wheel hub with rotor.

Refer to 40 FRONT SUSPENSION

Wheel speed sensor wire, replacing

Note. Always use repair kit VAS 1978 for repairs on wiring harnesses and connectors.

Special tools and equipment

1. Wiring harness repair kit VAS 1978

Removing

1. Remove screws (arrows).
2. Remove forward left-hand cover panel.

1. If installed, disconnect secondary air intake hose -1- from air cleaner.
2. Disconnect air hose -2- from mass air flow sensor.
3. Unplug connector -3- from mass air flow sensor.
4. Remove bolts -4- and -5-.

1. Remove air cleaner housing.

1. Release control module connector (arrow -1-) and unplug (arrow -2-).

Scheme 34

1. Loosen and remove cap of multi-pin connector using a screwdriver.

Scheme 35

1. Disengage secondary engagement device (violet) in direction of (arrow) using small screwdriver.

Scheme 36

Contact assignment of 47-pin connector on ABS control module (w/EDL) -J104

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations binder

Scheme 37

1. Using a suitable ejector tool from wiring repair kit VAS 1978, push out the relevant contacts.

Scheme 38

1. Unplug brake wear indicator connector -1- on left brake.
2. Unclip wiring from bracket -2-.
3. Release connector on wheel speed sensor and disconnect wiring.
4. Remove defective wiring for wheel speed sensor.

Installing

Install in reverse sequence; note the following points

1. Run in new wheel speed sensor wiring.

Scheme 39

1. Clip in speed sensor wiring (arrows).

Note. Make sure sensor wire is not twisted in wheel housing.

1. Guide contacts into connector housing.

Scheme 40

1. Push individual wiring seals in onto stop with an insertion tool from VAS 1978.
2. Secure contacts with secondary locking device and install multi-pin connector cover cap.

Tightening torque

Scheme 41

1 - Hex socket-head screw 8 Nm

2 - ABS wheel speed sensor

1. Removing and installing. Refer to «Speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__speed-sensor-removing-and-installing)
2. Before installing speed sensor, clean inner surface of hole and coat speed sensor all around with lubricant paste G 000 650
3. Replace speed sensor wire. Refer to «Speed sensor wire, replacing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__speed-sensor-wire-replacing)

3 - Stub axle

4 - Backing plate

5 - Wheel hub with wheel bearing and rotor

1. Checking rotor. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Replace only as complete unit
3. Removing and installing

Refer to 42 REAR SUSPENSION

6 - Self-locking 12-point nut

1. Tightening torque

Refer to 42 REAR SUSPENSION

7 - Cap

1. Removing and installing

Refer to 42 REAR SUSPENSION

8 - Brake disc

1. Application. Refer to «Application of PR Nos./brakes»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

9 - Phillips-head screw

1. Tightening torque. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

10 - Hex bolt, 60 Nm

1. With dished washer

11 - Axle beam

Speed sensor, removing and installing

Removing

1. Raise vehicle.

Scheme 42

1. Disconnect harness connector -1- from wheel speed sensor wire and wheel speed sensor.
2. Remove bolt -2- from stub axle.
3. Pull ABS wheel speed sensor out of stub axle.

Installing

Install in reverse sequence; note the following points

1. Before inserting wheel speed sensor, clean inner surface of bore hole and coat sensor completely with securing grease G 000 650

Tightening torque

1. Raise vehicle.
2. Remove wheel.

Scheme 43

1. Unscrew brake caliper housing -arrows- and hang to one side, securing it in position on vehicle with wire.

Note. Do not twist or kink brake hose/line.

Scheme 44

1. Rotate brake disc and check whether rotor -1- is damaged or dirty.
2. If rotor is damaged or in the event of excessive wheel bearing clearance, replace rotor together with wheel hub.

Refer to 42 REAR SUSPENSION

1. Install brake caliper housing. Refer to «Brake pads - vehicles with front-wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-vehicles-with-front-wheel) .

Speed sensor wire, replacing

Note. Always use repair kit VAS 1978 for repairs on wiring harnesses and connectors.

Special tools and equipment

Scheme 45

1. Wiring harness repair kit VAS 1978

Removing

1. Remove wheel housing liner.

Refer to 66 EXTERIOR EQUIPMENT

1. Release connector on wheel speed sensor and disconnect wiring.
2. Remove interior side panel trim.

Refer to 70 - INTERIOR TRIM

Scheme 46

1. Pull insulating grommet (arrow) off wiring connection.

Scheme 47

1. Cut speed sensor wiring with wire strippers VAS 1978/3 and remove defective wiring.

Installing

Install in reverse sequence; note the following points

Scheme 48

1. Strip 15 mm of insulation off the end of the wire using wire strippers from VAS 1978/3 and bend back the bare part of the wire over half its length.
2. Run in new wheel speed sensor wiring.

Scheme 49

1. Clip in speed sensor wiring (arrows).

Note. Make sure sensor wire is not twisted in wheel housing.

1. Cut 2-pin connector off new speed sensor wiring with wire stripper pliers.
2. Strip 15 mm of insulation from end of wire with wire strippers and bend back half.
3. Connect speed sensor wiring with aid of suitable crimp connector from wiring harness repair kit VAS 1978.

Note. The instructions supplied with wiring repair kit VAS 1978 normally do not permit repairs to the wiring of the ABS system. However, this only applies to the screened wiring in the system.

Scheme 50

1 - ABS wheel speed sensor

1. Removing and installing. Refer to «Speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Before installing speed sensor, clean inner surface of hole and coat speed sensor all around with lubricant paste G 000 650
3. Replacing speed sensor wire. Refer to «Speed sensor wire, replacing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

2 - Hex socket-head bolt 8 Nm

3 - Trailing arm

4 - Backing plate

5 - Hex bolt, 10 Nm

6 - Brake disc

1. Application. Refer to «Application of PR Nos./brakes»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

7 - Phillips-head screw

1. Tightening torque. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

8 - Wheel hub with rotor

1. Checking rotor. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Only replace complete
3. Removing and installing

Refer to 42 REAR SUSPENSION

9 - Snap ring

10 - Wheel bearing

1. Removing and installing

Refer to 42 REAR SUSPENSION

Removing

Scheme 51

1. Open cover -2- above connector for speed sensor.
2. Unplug electrical connector -1-.

Scheme 52

1. Remove bolt -1-.
2. Pull speed sensor out of trailing arm.

Installing

Install in reverse sequence; note the following points

1. Before inserting speed sensor, clean hole inner surface and coat speed sensor all-round with solid lubricant paste G 000 650.

Tightening torque

1. Remove bolt -1-.
2. Pull speed sensor out of trailing arm.
3. Remove wheel.
4. Rotate brake disc and check rotor for damage or dirt.

1. If rotor is damaged, remove wheel hub with rotor and replace.

Refer to 42 REAR SUSPENSION

1. Install speed sensor. Refer to «Speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .

Note. Always use repair kit VAS 1978 for repairs on wiring harnesses and connectors.

Special tools and equipment

1. Wiring harness repair kit VAS 1978

Removing

1. Open cover -2- above connector for speed sensor.
2. Unplug electrical connector -1-.
3. Remove interior side panel trim.

Refer to 70 - INTERIOR TRIM

1. Pull insulating grommet (arrow) off wire connection.

1. Cut speed sensor wiring with wire strippers VAS 1978/3 and remove defective wiring.

Installing

Install in reverse sequence; note the following points

1. Strip 15 mm of insulation off the end of the wire using wire strippers VAS 1978/3 and bend back the bare part of the wire over half its length.
2. Run in new wheel speed sensor wiring.

Scheme 53

1. Clip in speed sensor wiring -arrows-.

Note. Make sure sensor wire is not twisted in wheel housing.

1. Plug in electrical connector -1- and close cover -2-.
2. Cut 2-pin connector off new speed sensor wiring with wire stripper pliers.
3. Strip 15 mm of insulation from end of wire with wire strippers and bend back half.
4. Connect speed sensor wiring with aid of suitable crimp connector from wiring harness repair kit VAS 1978.

Note. The instructions supplied with wiring repair kit VAS 1978 normally do not permit repairs to the wiring of the ABS system. However, this only applies to the screened wiring in the system.

Scheme 54

1 - Right rear speed sensor rotor

1. Rotor is welded to wheel hub
2. Checking. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) and «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. Removing and installing

Refer to 42 REAR SUSPENSION

2 - Right rear ABS wheel speed sensor -G44

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) and «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

3 - Left rear ABS wheel speed sensor -G46

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) and «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

4 - Rotor for left rear speed sensor

1. Rotor is welded to wheel hub
2. Checking. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) and «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. Removing and installing

Refer to 42 REAR SUSPENSION

5 - Parking brake indicator light - K14

1. Installation location: in instrument cluster

6 - ABS warning light -K47

1. Installation location: in instrument cluster

7 - Warning light for brake system -K118

1. Installation location: in instrument cluster in driver information system (DIS)

8 - Traction control indicator light -K86

1. Installation location: in instrument cluster

9 - Brake light switch -F

1. Removing and installing. Refer to «Brake light switch, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-removing-and-installing)

10 - Rotor for left front ABS wheel speed sensor

1. Rotor is welded to wheel hub
2. Checking. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. Removing and installing

Refer to 40 FRONT SUSPENSION

11 - Left front ABS wheel speed sensor -G47

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

12 - ABS hydraulic unit -N55- with ABS Control Module (w/EDL) -J104

1. The hydraulic control unit comprises ABS hydraulic pump -V64-, hydraulic unit -N55- and ABS control module (w/EDL) -J104
2. Removing and installing. Refer to «Control module and hydraulic unit, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__control-module-and-hydraulic-unit-removing)

13 - Rotor for right front ABS wheel speed sensor

1. Rotor is welded to wheel hub
2. Checking. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. Removing and installing

Refer to 40 FRONT SUSPENSION

14 - Right front ABS wheel speed sensor -G45

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

15 - Longitudinal acceleration sensor -G251

1. Vehicles with all wheel drive only
2. Installation location: A-pillar on passenger`s side
3. Removing and installing. Refer to «Longitudinal acceleration sensor -G251- (vehicles up to approx. 08.01), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__longitudinal-acceleration-sensor-g251-vehicles-up)
4. Integrated into ESP sensor unit -G419- from approx. 09.01. See «ESP sensor unit -G419- from approx. 09.01»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

16 - Sensor -2- for brake pressure -G214

1. Removing and installing. Refer to «Brake pressure sensors, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

17 - Sender 1 for brake booster -1- -G201

1. Removing and installing. Refer to «Brake pressure sensors, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

18 - Brake fluid level warning switch -F34

19 - Sensor for transverse acceleration -G200

1. Removing and installing. Refer to «Sensor for transverse acceleration -G200- and Sender for rotation rate -G202- (vehicles up to approx. 08.01), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__sensor-for-transverse-acceleration-g200-and)
2. Integrated into ESP sensor unit -G419- from approx. 09.01. See «ESP sensor unit -G419- from approx. 09.01»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

20 - Sender for rotation rate -G202

1. Removing and installing. Refer to «Sensor for transverse acceleration -G200- and Sender for rotation rate -G202- (vehicles up to approx. 08.01), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__sensor-for-transverse-acceleration-g200-and)
2. Integrated into ESP sensor unit -G419- from approx. 09.01. See «ESP sensor unit -G419- from approx. 09.01»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

21 - Anti-Slip control switch -E132

1. Installation location: on center console

22 - ESP sensor unit -G419

1. From approx. 09.01. See «ESP sensor unit -G419- from approx. 09.01»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Removing and installing. Refer to «ESP sensor unit -G419-, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__esp-sensor-unit-g419-removing-and)

23 - Steering angle sensor -G85

1. Removing and installing. Refer to «Steering angle sensor -G85-, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

24 - Parking brake warning light switch -F9

1. Installation location: on parking brake lever module

Scheme 55

The ESP sensor unit -1- comprises of the senders listed below

1. Sensor for transverse acceleration -G200
2. Sender for rotation rate -G202
3. Longitudinal acceleration sensor -G251- (all wheel drive vehicles only)

ABS/ESP ITT Mark 60 system components

Note. The ESP road test ascertains the plausibility of the signals transmitted from sender 1 for brake booster -1- -G201-, sensor -2- for brake pressure -G214-, sensor for transverse acceleration -G200-, sender for rotation rate -G202- and the longitudinal acceleration sensor -G251- (vehicles with all wheel drive only). On vehicles from approx. 09.01 the three last-mentioned senders are integrated into the ESP sensor unit.

Brake light switch, removing and installing

Note. For a secure fit, the switch may only be installed once.

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

1. Unplug electrical connector.
2. Remove brake light switch by turning counter-clockwise 45 °.

Install in reverse sequence; note the following points

1. Pull brake light switch plunger fully out (arrow).
2. Install retainer tabs -1- and -2- on switch into recesses of installing hole and secure by turning clockwise 45 °.

Note. When installing brake light switch, do not operate brake pedal. The plunger is adjusted automatically when the brake light switch is inserted.

1. Make sure proper function of brake lights when brake pedal is pressed and released.

Sensor for transverse acceleration -G200- and Sender for rotation rate -G202- (vehicles up to approx. 08.01), removing and installing

Work procedure

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

1. Unplug electrical connectors (arrows) on sensors -G200-/-G202-.
2. Unscrew bolt -1- and remove mounting bracket for sensors -G200-/-G202-.

Removing and installing sender for rotation rate -G202

1. Unscrew nuts -a- and remove sender for rotation rate -G202- -1-.
2. To install: insert sender for rotation rate -G202- into mounting bracket and align straight before tightening.

Note. The sender for rotation rate is sensitive to shocks or impact. Do not install a sender which has dropped to the ground otherwise proper operation is not ensured.

Removing and installing sensor for transverse acceleration -G200

1. Use screwdriver to pry mount -1- off sensor for transverse acceleration -G200- -2- and remove sender.
2. To install insert sensor for transverse acceleration -G200- -1- in holder.

Scheme 56

1. Installation position: sloping side (arrow) of sensor for transverse acceleration -G200- must face mount -2-.

1. Slip mount over sensor for transverse acceleration -G200- until it engages with a click

Note. The lateral acceleration sender is not resistant to shocks or impact. Do not install a sender which has dropped to the ground otherwise proper operation is not ensured.

Installing

The remaining installation steps are carried out in the reverse sequence - note the following points

1. Initiate basic setting for sensor for transverse acceleration -G200- and sender for rotation rate -G202-.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. Perform ESP road test.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Tightening torques

Longitudinal acceleration sensor -G251- (vehicles up to approx. 08.01), removing and installing

Removing

1. Remove glove box

Refer to 68 - INTERIOR EQUIPMENT

1. Unplug electrical connector -2
2. Use a screwdriver to pry mount off longitudinal acceleration sensor -arrows- and remove sensor -G251- -1-.

Note. The longitudinal acceleration sensor is not resistant to shocks or impact. Do not install a sensor which has dropped to the ground otherwise proper operation is not ensured.

Installing

Install in reverse sequence; note the following points

1. Initiate basic setting for longitudinal acceleration sender -G251-.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. Perform ESP road test.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

ESP sensor unit -G419-, removing and installing

Removing

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

1. Remove bolts (arrows).
2. Pull ESP sensor unit -1- in direction of travel and out of holder.
3. Unplug electrical connector -2-.

Note. The ESP sensor unit is not resistant to shocks or impact. Do not install an ESP sensor which has dropped to the ground otherwise proper operation is not ensured.

Installing

Install in reverse sequence; note the following points

1. Initiate basic setting for the sensors in the ESP sensor unit.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. Perform ESP road test.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Tightening torque

Note. The coil connector with slip ring is enclosed in the housing of the steering angle sensor -G85-.

Removing

1. Turn wheels to straight ahead position.
2. Removing airbag unit and steering wheel.

Refer to 48 STEERING

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

1. Remove bolts -1- and detach handle for steering column adjustment -5-.
2. Remove bolts -2- to -4-.
3. Remove upper and lower sections of steering column trim.

1. Disconnect electrical connectors -1- and -2-.

1. Carefully lift upper retainer tabs -arrows-.
2. Carefully lift lower retainer tabs and pull off housing with coil connector, slip ring and steering angle sensor from steering column switch.

Installing

Install in reverse sequence; note the following points

1. Push on housing with coil connector, slip ring and steering angle sensor onto steering column switch until all retainer tabs engage with a click.
2. Break off transportation protection.

1. Adjust steering angle sensor to center position

1. Yellow dot must be visible in hole -arrow 1- and the two marks (arrows) must also be aligned.

1. Installing airbag unit and steering column.

Refer to 48 STEERING

1. Initiate basic settings for steering angle sender -G85-.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. Perform ESP road test.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Special tools and equipment

1. Brake filler and bleeder unit VAS 5234

Removing

1. Remove screws (arrows).

1. Remove forward left-hand cover panel.

1. If installed, disconnect secondary air intake hose -1- from air cleaner.
2. Disconnect air hose -2- from mass air flow sensor.
3. Unplug connector -3- from mass air flow sensor.
4. Unscrew bolts -4- and -5-.

1. Remove air cleaner housing.
2. Lay out sufficient lint-free cloths in area below brake master cylinder to catch escaping brake fluid.
3. Draw off as much brake fluid as possible from brake fluid reservoir using brake filler and bleeder unit VAS 5234.

1. Pull connector off relevant pressure sender (the one to be removed) -arrows-.

a - Sender 1 for brake booster -G201- in primary piston circuit

b - Sensor -2- for brake pressure -G214- in secondary piston circuit

1. Remove brake pressure sender.

Installing

Install in reverse sequence; note the following points

1. Bleed brake system. Refer to «ITT ABS/ESP Mark 60, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Bleed hydraulic system for clutch

Refer to 30 CLUTCH for 5 AND 6 SPD. MANUAL TRANSMISSION 02M, 02Y ALL WHEEL DRIVE or 30 CLUTCH for 5 SPD. MANUAL TRANSMISSION 02J FRONT WHEEL DRIVE

1. Initiate basic settings for brake pressure sensors.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. Perform ESP road test.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Tightening torques

Scheme 57

1. After connecting brake lines to hydraulic unit, perform final control diagnosis.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Note. Final control diagnosis can be performed to establish whether line connections have been interchanged.

1 - Cap nut - 20 Nm

2 - Torx socket head bolt - 4 Nm

3 - Brake line

1. Hydraulic unit to left rear brake caliper

4 - Torx socket head bolt - 4 Nm

5 - Brake line

1. Hydraulic unit to right rear brake caliper

6 - ABS hydraulic unit -N55

1. Installation location: in engine compartment, left side

7 - Brake line

1. Brake master cylinder/primary piston circuit to hydraulic unit

8 - Brake line

1. Hydraulic unit to left front brake caliper

9 - Brake line

1. Hydraulic unit to right front brake caliper

10 - Brake line

1. Brake master cylinder/secondary piston circuit to hydraulic unit

11 - ABS Control Module (w/EDL) -J104

1. Installed position in engine compartment, left side
2. The control module is bolted to the hydraulic unit

12 - Cap nut - 20 Nm

13 - Retainer

14 - Bolt - 8 Nm

Control module and hydraulic unit, removing and installing

Special tools and equipment

1. Brake pedal depressor VAG 1869/2
2. Repair kit

1 - Valve dome transportation protection (plastic foam)

2 - M10 sealing plugs for brake lines and threaded holes

3 - M12 sealing plugs for brake lines and threaded holes

After separating the control module from the hydraulic unit always install the valve dome transportation protection on the hydraulic unit.

Warranty claims for hydraulic units on which the valve dome transportation protection was not used, will not be accepted.

Removing

1. Remove screws (arrows).
2. Remove forward left-hand cover panel.

1. If installed, disconnect secondary air intake hose -1- from air cleaner.
2. Disconnect air hose -2- from mass air flow sensor.
3. Unplug connector -3- from mass air flow sensor.
4. Unscrew bolts -4- and -5-.

1. Remove air cleaner housing.

1. Insert brake pedal depressor VAG 1869/2 between brake pedal and driver's seat. Depress the brake pedal by at least 60 mm.
2. Connect hose of bleeder bottle to bleeder screws on left front and left rear brake calipers and open bleeder screws.

Note. This dissipates pressure in hydraulic unit.

1. Close left front and left rear bleeder screws.
2. Do not remove brake pedal depressor VAG 18169/2.

Scheme 58

1. Release control module connector -arrow 1- and unplug -arrow 2-.

Note. Protect connector housing of control module against escaping brake fluid. Otherwise corroding contacts can cause a breakdown of the system. Carefully clean a moist or dirty connector housing with compressed air.

1. Lay out sufficient lint-free cloths in area below control module and hydraulic unit.
2. Mark brake lines.

Scheme 59

1. Disconnect brake lines -1- from hydraulic unit to brake master cylinder and tie up.
2. Disconnect remaining brake lines from hydraulic unit.

1. Seal brake lines and threaded holes with plugs from repair set.
2. Unscrew bolts at hydraulic unit -arrows- and take out hydraulic unit and control module.

Removing control module from hydraulic unit

1. Place hydraulic unit with control module down on a clean flat surface.

Scheme 60

1. Remove Torx socket head bolts -arrows-.

1. Separate hydraulic unit with hydraulic pump from control module by lifting carefully off joint -1-.

Scheme 61

1. When detaching control module, make sure valve domes of hydraulic unit do not catch on control module solenoids.
2. Cover control unit solenoids with a lint free cloth.
3. Protect components against moisture.
4. Install transportation protection for valve domes (enclosed in repair kit) after separating control module and hydraulic unit.

Note. The valve dome -2- supplied as spare part with the control module can only be clipped in once. It is not possible to separate the connection afterward.

Installing

Install in reverse sequence; note the following points

Note. Only remove sealing plugs on new hydraulic unit when the corresponding brake line is going to be installed. If the sealing plugs are removed too soon from the hydraulic unit, brake fluid may escape, it may no longer be possible to fill and bleed the unit properly.

1. When assembling control module and hydraulic unit, make sure valve domes of hydraulic unit do not catch on control module solenoids.
2. Connect lines as previously marked. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .
3. Bolt ABS module to bracket.

Note. Do not fully tighten bolts. This facilitates attachment of individual brake lines to hydraulic unit.

1. After tightening brake lines, tighten hydraulic unit.
2. Bleed brake system. Refer to «ITT ABS/ESP Mark 60, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .
3. If a new control module has been installed it must be coded.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. After connecting brake lines to hydraulic unit, perform final control diagnosis.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Note. Final control diagnosis can be used to establish whether line connections have been interchanged.

Tightening torques

1) Replace bolts

2) For M10-connections and M12-connections

Exploded view

1 - ABS wheel speed sensor

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Before inserting sensor, clean installing hole inner surface and coat with lubricating paste G 000 650
3. Replacing speed sensor wire. Refer to «ABS wheel speed sensor wire, replacing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__abs-wheel-speed-sensor-wire-replacing)

2 - Wheel bearing housing

3 - Hex socket head bolt - 8 Nm

4 - Backing plate

5 - Bolt

1. Tightening torque. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

6 - Wheel bearing

1. Removing and installing

Refer to 40 FRONT SUSPENSION

7 - Phillips-head screw

1. Tightening torque. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) verify

8 - Brake disc

1. Application. Refer to «Application of PR Nos./brakes»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

9 - Wheel hub with rotor

1. Checking rotor. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Only replace complete

Refer to 40 FRONT SUSPENSION

10 - Circlip

Removing

1. Release connector -1- on wheel speed sensor and disconnect wiring.
2. Unscrew bolt -2-.
3. Pull speed sensor out of wheel bearing housing.

Installing

Install in reverse sequence; note the following points

1. Before inserting speed sensor, clean hole inner surface and coat speed sensor all-round with solid lubricant paste G 000 650.
2. Turn wheels fully onto left and right-hand lock and check clearance to speed sensor wiring.

Tightening torque

1. Remove wheel.
2. Rotate disc brake and check rotor for damage or dirt.
3. If rotor is damaged, remove and replace wheel hub with rotor.

Refer to 40 FRONT SUSPENSION

Checking rotor lateral run-out

1. Turn wheel hub and check that gap -a- between rotor and speed sensor is uniform.

1. Distance a = 0.3 mm

1. If lateral run-out is out of tolerance, remove and replace wheel hub with rotor.

Refer to 40 FRONT SUSPENSION

ABS wheel speed sensor wire, replacing

Note. Always use repair kit VAS 1978 for repairs on wiring harnesses and connectors.

Special tools and equipment

1. Wiring harness repair kit VAS 1978

Removing

1. Remove screws (arrows).
2. Remove forward left-hand cover panel (arrows).

1. If installed, disconnect secondary air intake hose -1- from air cleaner.
2. Disconnect air hose -2- from mass air flow sensor.
3. Unplug connector -3- from mass air flow sensor.
4. Unscrew bolts -4- and -5-.

1. Remove air cleaner housing.

1. Release control unit connector (arrow -1-) and unplug (arrow -2-).

1. Release cap on multi-pin connector with a screwdriver and remove.

1. Release secondary catch (violet) with a small screwdriver by pressing in direction indicated (arrow).

Scheme 62

Contact assignment of 47-pin connector on ABS Control Module (w/EDL) -J104

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations

1. Using a suitable ejector tool from wiring repair kit VAS 1978, push out the relevant contacts.

1. Unplug brake wear indicator connector -1- on left brake.
2. Unclip wiring from bracket -2-.
3. Release connector on wheel speed sensor and disconnect wiring.
4. Remove defective wiring for wheel speed sensor.

Installing

Install in reverse sequence; note the following points

1. Install new wheel speed sensor wiring.

1. Clip in speed sensor wiring (arrows).

Note. Make sure sensor wire is not twisted in wheel housing.

1. Guide contacts into connector housing.

1. Push individual wiring seals in onto stop with an insertion tool from VAS 1978.
2. Secure contacts with secondary locking device and install multi-pin connector cover cap.

Tightening torque

1 - Hex socket head bolt - 8 Nm

2 - ABS wheel speed sensor

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Before inserting sensor, clean inner surface of hole and coat speed sensor all around with lubricant paste G 000 650
3. Replacing speed sensor wire. Refer to «ABS wheel speed sensor wire, replacing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

3 - Stub axle

4 - Backing plate

5 - Wheel hub with wheel bearing and rotor

1. Checking rotor. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Only replace complete
3. Removing and installing

Refer to 42 REAR SUSPENSION

6 - 12-point nut

1. Tightening torque

Refer to 42 REAR SUSPENSION

7 - Grease cap

1. Removing and installing

Refer to 42 REAR SUSPENSION

8 - Brake disc

1. Application. Refer to «Application of PR Nos./brakes»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

9 - Cross-head screw

1. Tightening torque. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

10 - Bolt - 60 Nm

11 - Axle beam

Removing

1. Release connector -1- on wheel speed sensor and disconnect wiring.
2. Remove bolt -2-.
3. Pull speed sensor out of stub axle.

Installing

Install in reverse sequence; note the following points

1. Before inserting speed sensor, clean hole inner surface and coat speed sensor all-round with solid lubricant paste G 000 650.

Tightening torque

1. Remove wheel.

1. Remove brake caliper housing (arrows) and hang to one side securing it in position on vehicle with wire.

Note. Do not twist or kink brake hose/line.

1. Rotate brake disc and check whether rotor -1- is damaged or dirty.
2. If rotor is damaged or in the event of excessive wheel bearing clearance, replace rotor together with wheel hub.

Refer to 42 REAR SUSPENSION

1. Install brake caliper housing. Refer to «Brake pads - vehicles with front-wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-vehicles-with-front-wheel) .

Note. Always use repair kit VAS 1978 for repairs on wiring harnesses and connectors.

Special tools and equipment

1. Wiring harness repair kit VAS 1978

Removing

1. Remove wheel housing liner.

Refer to 66 EXTERIOR EQUIPMENT

1. Release connector on wheel speed sensor and disconnect wiring.
2. Remove interior side panel trim.

Refer to 70 - INTERIOR TRIM

1. Pull insulating grommet (arrow) off wiring connection.

1. Cut speed sensor wiring with wire strippers VAS 1978/3 and remove defective wiring.

Installing

Install in reverse sequence; note the following points

1. Strip 15 mm of insulation off the end of the wire using wire strippers from VAS 1978/3 and bend back the bare part of the wire over half its length.
2. Install new wheel speed sensor wiring.

1. Clip in speed sensor wiring (arrows).

Note. Make sure sensor wire is not twisted in wheel housing.

1. Cut 2-pin connector off new speed sensor wiring with wire stripper pliers.
2. Strip 15 mm of insulation from end of wire with wire strippers and bend back half.
3. Connect speed sensor wiring with aid of suitable crimp connector from wiring harness repair set VAS 1978.

Note. The instructions supplied with wiring repair kit VAS 1978 normally do not permit repairs to the wiring of the ABS system. This only applies to the screened wiring in the system.

1 - Speed sensor

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Before inserting sensor, clean inner surface of hole and coat speed sensor all around with lubricant paste G 000 650
3. Replacing speed sensor wire. Refer to «ABS wheel speed sensor wire, replacing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

2 - Hex socket head bolt - 8 Nm

3 - Trailing arm

4 - Backing plate

5 - Bolt - 10 Nm

6 - Brake disc

1. Application. Refer to «Application of PR Nos./brakes»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

7 - Phillips-head screw

1. Tightening torque. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) verify

8 - Wheel hub with rotor

1. Checking rotor. Refer to «Rotor, checking»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Only replace complete
3. Removing and installing

Refer to 42 REAR SUSPENSION

9 - Circlip

10 - Wheel bearing

1. Removing and installing

Refer to 42 REAR SUSPENSION

Removing

1. Open cover -2- above connector for speed sensor.
2. Unplug electrical connector -1-.

1. Remove bolt -1-.
2. Pull speed sensor out of trailing arm.

Installing

Install in reverse sequence; note the following points

1. Before inserting speed sensor, clean hole inner surface and coat speed sensor all-round with solid lubricant paste G 000 650.

Tightening torque

1. Remove bolt -1-.
2. Pull speed sensor out of trailing arm.
3. Remove wheel.
4. Rotate disc brake and check rotor for damage or dirt.

1. If rotor is damaged, remove wheel hub with rotor and replace.

Refer to 42 REAR SUSPENSION

1. Installing speed sensor. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .

Note. Always use repair kit VAS 1978 for repairs on wiring harnesses and connectors.

Special tools and equipment

1. Wiring harness repair kit VAS 1978

Removing

1. Open cover -2- above connector for speed sensor.
2. Unplug electrical connector -1-.
3. Remove interior side panel trim.

Refer to 70 - INTERIOR TRIM

1. Pull insulating grommet (arrow) off wire connection.

1. Cut speed sensor wiring with wire strippers VAS 1978/3 and remove defective wiring.

Installing

Install in reverse sequence; note the following points

1. Strip 15 mm of insulation off the end of the wire using wire strippers VAS 1978/3 and bend back the bare part of the wire over half its length.
2. Install new wheel speed sensor wiring.

1. Clip in speed sensor wiring (arrows).

Note. Make sure sensor wire is not twisted in wheel housing.

1. Plug in electrical connector -1- and close cover -2-.
2. Cut 2-pin connector off new speed sensor wiring with wire stripper pliers.
3. Strip 15 mm of insulation from end of wire with wire strippers and bend back half.
4. Connect speed sensor wiring with aid of suitable crimp connector from wiring harness repair set VAS 1978.

Note. The instructions supplied with wiring repair kit VAS 1978 normally do not permit repairs to the wiring of the ABS system. However, this only applies to the screened wiring in the system.

Front brake, servicing

Note. For extracting brake fluid from reservoir, always use brake filler and bleeder unit VAS 5234. Prior to removing a brake caliper or disconnecting a brake hose from the brake caliper, use brake pedal depressor VAG 1869/2 to prevent the brake fluid reservoir from running dry.

Scheme 63

General notes. Refer to Front brake, servicing

1 - Philips-head screw - 4 Nm

2 - Brake disc

1. Application, dimensions, wear limit. Refer to «Application of PR Nos./brakes»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Unscrew brake caliper housing prior to removing
3. Never remove brake discs from hub by force. If necessary, use penetrating fluid, otherwise brake discs can be damaged.
4. When worn always replace both sides

3 - Brake pads

1. Pad thickness, wear limit. Refer to
2. Different versions possible
3. Checking pad thickness

Refer to 01 MAINTENANCE

1. Removing and installing. Refer to «Brake pads - Front brakes FN 3, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-front-brakes-fn)
2. Note installation position. See «Installation position of brake pads»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. When worn always replace both sides

4 - Retaining spring

1. Insert in both brake caliper housing holes

5 - Brake carrier

1. Replacement brake carriers are supplied assembled and with sufficient grease at guide pins
2. Install repair set in the event of damage to protective caps; use pad provided to grease guide pins.

6 - Brake caliper housing

1. Piston diameter, Technical data: Refer to
2. Remove from brake carrier to replace brake pads
3. Removing and installing. Refer to «Brake caliper - Front brakes FN 3, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-caliper-front-brakes-fn)
4. Servicing. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

7 - Guide pin - 28 Nm

8 - Protective cap

9 - Brake hose with banjo union and banjo bolt - 35 Nm

1. Anti-twist element. See «Brake hose connection with anti-twist element»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

10 - Ribbed bolt - 125 Nm

1. Clean ribs if using again

11 - Wheel bearing housing

1. Different versions possible

12 - Hex head bolt

1. Tightening torque. Refer to «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

13 - Speed sensor

1. Removing and installing. Refer to «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__abs-wheel-speed-sensor-removing-and)

14 - Backing plate

15 - Bolt - 10 Nm

16 - Wheel bearing

1. Removing and installing

Refer to 40 FRONT SUSPENSION

17 - Circlip

18 - Wheel hub with rotor

1. Removing and installing

Refer to 40 FRONT SUSPENSION

19 - Brake pads

1. With wear indicator (left side only)

1. Warning lamp in instrument cluster lights up when wear limit is reached

1. Pad thickness, wear limit. Refer to
2. Different versions possible
3. Checking pad thickness

Refer to 01 MAINTENANCE

1. Removing and installing. Refer to «Brake pads - Front brakes FN 3, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-front-brakes-fn)
2. Note installation position. See «Installation position of brake pads»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. When worn always replace both sides

20 - Electrical connector

1. Remove from bracket -item 21- «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) when changing pads

21 - Bracket

22 - Self-metal screw

Scheme 64

1 - Right-side piston brake pad

2 - Left-side piston brake pad

1. When installed, (arrow) on backplate of brake pad must face downward.

Scheme 65

1. Make sure that the groove in the ring connection on the brake hose is installed in the locating lug (arrow).

Brake pads - Front brakes FN 3, removing and installing

Special tools and equipment

1. Piston resetting tool

1. Remove both front wheels.

Scheme 66

1. Disconnect brake wear indicator connector -1- on left brake.

Scheme 67

1. Pry off brake pad retaining spring from brake caliper housing using a screwdriver (arrow) and detach.

Scheme 68

1. Remove protective caps (arrows).

Scheme 69

1. Unscrew guide pins (arrows).
2. Detach brake caliper housing and secure on vehicle with wire.

Note. Do not twist or kink brake hose/line.

1. Take brake pads out of brake caliper housing or from brake carrier.

Note. If reusing brake pads mark location and install in same position when installing otherwise it will cause uneven braking!

Install in reverse sequence; note the following points

1. Clean brake caliper housing, in particular the bonding surface for the brake pad. It must be free of adhesive and grease residues.

Use methylated spirit only for cleaning the brake caliper housing.

Scheme 70

1. Press piston back.

Note. Before inserting new brake pads, press piston back into the cylinder with resetting tool. Before pressing the piston back, draw off brake fluid from the reservoir with a bleeder bottle. Otherwise if reservoir has been topped off, fluid will overflow and cause damage.

1. Note installation position, insert brake pads.

1 - Right-side piston brake pad

2 - Left-side piston brake pad

1. When installed, (arrow) on backplate of brake pad must face downward.

1. Install outer brake pad to brake carrier.

Scheme 71

1. Pull protective foil off outer brake pad backplate.

1. Insert retaining spring (arrow) into brake caliper housing.

1. Check brake fluid level and top off, if necessary.

Tightening torque

Brake caliper - Front brakes FN 3, removing and installing

Special tools and equipment

1. Brake pedal depressor VAG 1869/2

Removing

1. Remove brake pads. Refer to «Brake pads - Front brakes FN 3, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-front-brakes-fn) .

1. Insert brake pedal depressor VAG 1869/2 between brake pedal and driver's seat. Depress the brake pedal by at least 60 mm.

Note. Pressing down the brake pedal closes the valves in the brake master cylinder to prevent the brake fluid reservoir from running dry.

1. Connect bleeder bottle hose to bleeder screw on removed brake caliper.
2. Open bleeder screw.
3. Do not remove brake pedal depressor VAG 18169/2.
4. Remove brake hose from brake caliper.

Installing

Install in reverse sequence; note the following points

1. Install brake pads. Refer to «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .
2. Bleed brake system: ABS/ESP Mark 20. Refer to «ABS/ESP ITT Mark 20, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) , ABS/ESP Mark 60. Refer to «ITT ABS/ESP Mark 60, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .

Tightening torque

Scheme 72

Special tools and equipment

1. V.A.G 1331 Torque wrench
2. V.A.G 1410 Torque wrench
3. V.A.G 1869/2 Brake pedal depressor

Note. After replacing brake pads, depress brake pedal firmly several times with vehicle stationary so that the brake pads are properly seated in the normal operating position. For extracting brake fluid from reservoir, always use brake filler bleeder unit VAS 5234 or extraction unit V.A.G 1869/4. Apply brake pedal depressor V.A.G 1869/2 before removing a brake caliper or disconnecting a brake hose from the caliper. Tightening torques for wheel bolts Installing wheels tightening torque: 120 Nm

1 - Phillips-head screw, 4 Nm

Scheme 73

2 - Brake disc

1. When worn always replace both sides
2. Application, dimensions, wear limit. Refer to «Application of PR Nos./brakes»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. Left and right discs are different; arrow shows direction of rotation
4. Unbolt brake caliper before removing

3 - Brake pads

1. With wear indicator

1. Warning lamp lights up in instrument cluster when wear limit is reached (approx. 4 mm)

1. Checking thickness

Refer to 01 MAINTENANCE

1. Always renew both sides together
2. Removing and installing. Refer to «Brake pads, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-removing-and-installing)

4 - Retaining spring

1. Press under brake carrier and insert in two holes in brake caliper housing

Note. If the retaining spring is installed incorrectly, the wear of the outer pad cannot be compensated, so brake pedal travel will increase accordingly.

5 - Brake carrier

1. Bolted onto wheel bearing housing

6 - Brake caliper housing

1. Do not disconnect brake hose when changing pads
2. Removing

1. Remove brake pads. Refer to «Brake pads, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-removing-and-installing)
2. Apply brake pedal depressor V.A.G 1869/2
3. Unscrew brake hose -Item 12- «Brake caliper 2FN, servicing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) from caliper

1. Installing

1. Install brake pads. Refer to «Brake pads, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-removing-and-installing)
2. Screw brake hose -Item 12- «Brake caliper 2FN, servicing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) onto caliper
3. Take out brake pedal depressor V.A.G 1869/2
4. Bleed brake system (Mark 60). Refer to «ITT ABS/ESP Mark 60, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

1. Servicing. Refer to «Brake caliper 2FN, servicing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Hose must not be twisted when installed

7 - Bushing

8 - Guide pin, 25 Nm

9 - Cap

1. Detach
2. Upper cap combined with wiring retainer for pad wear indicator

10 - Bracket

1. Bolted to brake caliper housing

11 - Hex bolt, 8 Nm

12 - Brake hose/line, 15 Nm

1. Screw into brake caliper housing
2. Do not disconnect brake hose when changing pads
3. Hose must not be twisted when installed

13 - Ribbed bolt, 125 Nm

1. Clean if re-installed

14 - Wheel bearing housing

15 - Socket head bolt, 8 Nm

16 - ABS wheel speed sensor

1. Before installing sensor, clean inside of bore and lubricate with grease G 000 650

17 - Backing plate

18 - Hex bolt, 10 Nm

19 - Wheel hub with rotor

1. Removing and installing

Refer to 40 FRONT SUSPENSION

20 - Connector

21 - Bracket

22 - Bolt

Brake pads, removing and installing

Special tools and equipment

Scheme 74

1. V.A.G 1331 Torque wrench
2. Piston resetting tool

Removing

Note. If reusing brake pads mark location and install in same position when installing otherwise it will cause uneven braking!

1. Remove wheels

Scheme 75

1. Secure brake disc with one wheel bolt.

Scheme 76

1. Push retaining spring in -A- until you can pry it out of bore in brake caliper.

Scheme 77

1. Pull bottom of retaining spring in direction -A- and hold in this position. Push top of retaining spring in direction -B-. At the same time, turn spring slightly counter-clockwise and pull it out of bore in caliper (arrow -D-).

Scheme 78

1. Unplug connector -1- for pad wear indicator.
2. Detach wire for pad wear indicator from retainer -2- on upper cap and from retainer -3- on dust cap.

Scheme 79

1. Take off caps -1-.

Note. Upper cap is combined with wiring retainer for pad wear indicator.

Scheme 80

1. Unscrew and remove both guide pins from brake caliper.
2. Detach brake caliper housing and put it aside so that the weight of the caliper does not strain or damage the brake hose.
3. Take brake pads out of caliper housing and brake carrier.

Use only methylated spirits to clean brake caliper housing.

Installing

Note. Before inserting new brake pads, push pistons back into cylinder with the resetting tool. Before pushing the pistons back, draw off brake fluid from the reservoir using a bleeder bottle. Otherwise (particularly if reservoir has been topped off) fluid will overflow and cause damage.

Scheme 81

1. Push back pistons.

Scheme 82

1. Install brake pad with retaining spring in caliper housing (pistons).
2. Install outer brake pad on brake carrier.

1. Secure brake caliper housing to brake carrier with two guide pins.
2. Install both caps.

Note. Upper cap is combined with wiring retainer for pad wear indicator.

1. Install wire for pad wear indicator under dust cap -3- on bleeder valve and in retainer -2- on upper cap.
2. Attach connector -1- for pad wear indicator.

Scheme 83

1. Locate retaining spring at top of brake carrier. Press top of retaining spring in direction -B-, and at the same time hold bottom of spring by exerting pressure in the opposite direction -A-. Now push retaining spring into bore in brake caliper.

Scheme 84

1. Locate retaining spring at bottom of brake carrier. Then press retaining spring in direction -A- first, hold in this position and at the same time press into bore in brake caliper.
2. Installing wheels, tightening torque: 120 Nm

Refer to 44 WHEELS, TIRES, WHEEL ALIGNMENT

Note. After changing brake pads, press brake pedal firmly several times with vehicle stationary to ensure that pads become properly seated. Check brake fluid level after changing brake pads.

Rear brake, servicing

Note. For extracting brake fluid from reservoir always use brake filler and bleeder unit VAS 5234. Prior to removing a brake caliper or disconnecting a brake hose from the brake caliper apply brake pedal depressor VAG 1869/2 to prevent the brake fluid reservoir from running dry.

Scheme 85

General notes. Refer to Rear brake, servicing

1 - Phillips-head screw - 4 Nm

2 - Brake disc

1. Application, dimensions, wear limit. Refer to «Application of PR Nos./brakes»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Never remove brake discs from hub by force. If necessary use penetrating fluid, otherwise brake discs can be damaged.
3. When worn always replace both sides

3 - Grease cap

1. Removing and installing

Refer to 42 REAR SUSPENSION

4 - 12-point nut

1. Tightening torque

Refer to 42 REAR SUSPENSION

5 - Wheel hub with wheel bearing and rotor

1. Only replace complete
2. Removing and installing

Refer to 42 REAR SUSPENSION

6 - Bolt - 60 Nm

7 - Backing plate

8 - Stub axle

9 - Parking brake cable

1. Removing and installing. Refer to «Parking brake cable - vehicles with front-wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-cable-vehicles-with)
2. Adjusting parking brake. Refer to «Parking brake, adjusting»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-adjusting)

10 - Axle beam

11 - Speed sensor

1. Removing and installing. Refer to «Speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__speed-sensor-removing-and-installing) and «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

12 - Hex head bolt

1. Tightening torque. Refer to «Speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__speed-sensor-removing-and-installing) and «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

13 - Hex socket head bolt - 65 Nm

14 - Brake carrier

1. With guide pins and protective cap
2. Supplied as replacement part assembled with sufficient grease on guide pins
3. Install repair kit in the event of damage to protective caps; use pad provided to grease guide pins.

15 - Brake hose/line

1. With banjo bolt and seals
2. Replace if banjo bolt is loosened
3. Tighten banjo bolt to 38 Nm

16 - Bolt - 35 Nm

1. Self-locking
2. When loosening and tightening counter hold on guide pin
3. Replace each time after removing

17 - Brake caliper housing

1. Piston diameter. Refer to
2. Different versions possible
3. Removing and installing. Refer to «Brake caliper - vehicles with front-wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-caliper-vehicles-with-front-wheel)
4. Servicing. Refer to «Rear brake caliper, servicing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__rear-brake-caliper-servicing)

1. Adjust parking brake cable first after maintenance or replacement. Refer to «Parking brake, adjusting»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-adjusting)

18 - Brake pads

1. Pad thickness, wear limit. Refer to
2. Checking pad thickness

Refer to 01 MAINTENANCE

1. Removing and installing. Refer to «Brake pads - vehicles with front-wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-vehicles-with-front-wheel)
2. When worn always replace both sides

19 - Pad retaining springs

1. Always replace when changing pads

Brake pads - vehicles with front-wheel drive, removing and installing

Special tools and equipment

Scheme 86

1. 3272 Piston compressing and extracting tool

1. Remove wheels.

Scheme 87

1. Pry off clip -1- for parking brake cable.
2. Press brake lever -2- in direction of arrow and unhook brake cable -3-.

Scheme 88

1. Counterhold guide pin, to detach brake caliper housing.
2. Secure brake caliper housing on vehicle with wire.

Note. Do not twist or kink brake hose/line.

Scheme 89

1. Remove brake pads and pad retaining springs -arrows-.

Note. If reusing brake pads mark location and install in same position when installing, otherwise it will cause uneven braking!

Install in reverse sequence; note the following points

1. Clean brake caliper housing, in particular the bonding surface for the brake pad. It must be free of adhesive and grease residues.

Use methylated spirit only for cleaning the brake caliper housing.

Note. Prior to pressing the piston back, draw off brake fluid from the reservoir. Use a bleeder bottle or a plastic bottle which is only used for brake fluid.

Scheme 90

1. Apply special tool 3272 together with 3272/1 to piston on brake caliper housing.
2. Screw in piston by turning knurled wheel of special tool 3272 clockwise, do not damage protective cap when doing this.

Note. If piston is stiff, use a 13 mm open-ended wrench to apply at appropriate flats -arrow-.

1. Insert brake pads and brake pad retaining springs -arrows- into brake carrier.
2. Pull protective foil off outer brake pad backplate.
3. Secure brake caliper housing with new self-locking bolts.

Note. The repair kit contains four self-locking hex bolts, which must always be installed.

1. Press brake lever -2- in direction of arrow and attach parking brake cable.
2. Open clip -1- securing parking brake cable.

1. Check brake fluid level and top off, if necessary.

Tightening torques

1) Replace bolts

Brake caliper - vehicles with front-wheel drive, removing and installing

Special tools and equipment

1. Brake pedal depressor VAG 1869/2

Removing

1. Remove brake pads. Refer to «Brake pads - vehicles with front-wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-vehicles-with-front-wheel) .

1. Insert brake pedal depressor VAG 1869/2 between brake pedal and driver's seat. Depress the brake pedal by at least 60 mm.

Note. Pressing down the brake pedal closes the valves in the brake master cylinder to prevent the brake fluid reservoir from running dry.

1. Connect bleeder bottle hose to bleeder screw on removed brake caliper.
2. Open bleeder screw.
3. Do not remove brake pedal depressor VAG 18169/2.
4. Unscrew brake hose from brake caliper.

Installing

Install in reverse sequence; note the following points

1. Install brake pads. Refer to «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .
2. After servicing or replacing, parking brake cable must be adjusted first. Adjust parking brake: Refer to «Parking brake, adjusting»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-adjusting) . Do not press foot brake until parking brake has been adjusted.
3. Bleed brake system: ABS/ESP Mark 20. Refer to «ABS/ESP ITT Mark 20, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) , ABS/ESP Mark 60. Refer to «ITT ABS/ESP Mark 60, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .

Tightening torque

1) Always replace brake hose/brake line with banjo bolt after removing banjo bolt.

Scheme 91

1 - Hex socket head bolt - 65 Nm

2 - Brake carrier

1. With guide pins and protective cap
2. Supplied as replacement part assembled with sufficient grease on guide pins
3. Install repair kit in the event of damage to protective caps; use pad provided to grease guide pins.

3 - Bolt - 35 Nm

1. Self-locking
2. Replace each time after removing
3. When loosening and tightening counter hold on guide pin

4 - Brake hose/line

1. With banjo bolt and seals
2. After unscrewing banjo bolt, replace banjo bolt with angled sealing element
3. Tighten banjo bolt to 38 Nm

5 - Brake caliper housing

1. Piston diameter. Refer to
2. Different versions possible
3. Removing and installing. Refer to «Brake caliper - vehicles with all wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-caliper-vehicles-with-all)
4. Servicing. Refer to «Rear brake caliper, servicing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__rear-brake-caliper-servicing)

1. Adjust parking brake cable first after maintenance or replacement. Refer to «Parking brake, adjusting»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-adjusting)

6 - Brake pads

1. Pad thickness, wear limit. Refer to
2. Different versions possible
3. Checking pad thickness

Refer to 01 MAINTENANCE

1. Removing and installing. Refer to «Brake pads - vehicles with all wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-vehicles-with-all)
2. When worn always replace both sides

7 - Pad retaining springs

1. Always replace when changing pads

8 - Backing plate

9 - Bolt - 10 Nm

10 - Brake disc

1. Application, dimensions, wear limit. Refer to «Application of PR Nos./brakes»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Different versions possible
3. Never remove brake discs from hub by force. If necessary use penetrating fluid, otherwise brake discs can be damaged.
4. When worn always replace both sides

11 - Phillips-head screw - 4 Nm

12 - Wheel hub with rotor

1. Removing and installing

Refer to 42 REAR SUSPENSION

13 - Circlip

14 - Wheel bearing

1. Removing and installing

Refer to 42 REAR SUSPENSION

15 - Trailing arm

16 - Speed sensor

1. Removing and installing. Refer to «Speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) and «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

17 - Hex head bolt

1. Tightening torque. Refer to 45-58 and «ABS wheel speed sensor, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

18 - Parking brake cable

1. Removing and installing. Refer to «Parking brake cable - vehicles with all wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-cable-vehicles-with)
2. Adjusting parking brake. Refer to «Parking brake, adjusting»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-adjusting)

Brake pads - vehicles with all wheel drive, removing and installing

Special tools and equipment

1. 3272 Piston compressing and extracting tool

1. Remove wheels.

Scheme 92

1. Pry off clip -1- for parking brake cable.
2. Press brake lever -2- in direction of arrow and unhook brake cable -3-.

Scheme 93

1. Counterhold guide pin, to detach brake caliper housing.
2. Secure brake caliper housing on vehicle with wire.

Note. Do not twist or kink brake hose/line.

1. Remove brake pads and pad retaining springs (arrows).

Note. If reusing brake pads mark location and install in same position when installing, otherwise it will cause uneven braking!

Install in reverse sequence; note the following points

1. Clean brake caliper housing, in particular the bonding surface for the brake pad. It must be free of adhesive and grease residues.

Use methylated spirit only for cleaning the brake caliper housing.

Note. Prior to pressing the piston back, draw off brake fluid from the reservoir. Use a bleeder bottle or a plastic bottle which is only used for brake fluid.

1. Apply special tool 3272 together with 3272/1 to piston on brake caliper housing.
2. Screw in piston by turning knurled wheel of special tool 3272 clockwise, do not damage protective cap when doing this.

Note. If piston is stiff, use a 13 mm open-ended wrench to be applied at appropriate flats (arrow).

1. Insert brake pads and brake pad retaining springs -arrows- into brake carrier.
2. Pull protective foil off outer brake pad backplate.
3. Secure brake caliper housing with new self-locking bolts.

Note. The repair kit contains four self-locking hex bolts, which must always be installed.

1. Press brake lever -2- in direction of arrow and attach parking brake cable.
2. Open clip -1- securing parking brake cable.

1. Check brake fluid level and top off, if necessary.

Tightening torque

1) Replace bolts

Brake caliper - vehicles with all wheel drive, removing and installing

Special tools and equipment

1. Brake pedal depressor VAG 1869/2

Removing

1. Remove brake pads. Refer to «Brake pads - vehicles with all wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pads-vehicles-with-all) .

1. Insert brake pedal depressor VAG 1869/2 between brake pedal and driver's seat. Depress the brake pedal by at least 60 mm.

Note. Pressing down the brake pedal closes the valves in the brake master cylinder to prevent the brake fluid reservoir from running dry.

1. Connect bleeder bottle hose to bleeder screw of removed brake caliper.
2. Open bleeder screw.
3. Do not remove brake pedal depressor VAG 18169/2.
4. Unscrew brake hose from brake caliper.

Installing

Install in reverse sequence; note the following points

1. Install brake pads. Refer to «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .
2. After servicing or replacing, new brake caliper, parking brake cable must be adjusted. Adjust parking brake. Refer to «Parking brake, adjusting»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-adjusting) . Do not press foot brake until parking brake has been adjusted.
3. Bleed brake system: ABS/ESP Mark 20. Refer to «ABS/ESP ITT Mark 20, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) , ABS/ESP Mark 60. Refer to «ITT ABS/ESP Mark 60, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .

Tightening torque

1) Always replace brake hose/line with banjo bolt after removing banjo bolt.

Scheme 94

1 - Parking brake lever

1. The parking brake lever is supplied as spare part assembled with pull rod, locking pawl, pushrod, push button, compression spring and ratchet
2. Before removing take out rear section of center console

Refer to 68 - INTERIOR EQUIPMENT

2 - Lock washer

3 - Parking brake lever trim

1. Pull off forward

4 - Nut - 18 Nm

5 - Pull rod

6 - Compensator

7 - Nut - 8 Nm

1. Self-locking
2. To adjust parking brake
3. Adjusting parking brake. Refer to «Parking brake, adjusting»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-adjusting)

8 - Pivot pin

1. For parking brake lever
2. Insert pull rod -Item 5- «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) into hole of pivot pin.

9 - Parking brake cable

1. Removing and installing on vehicles with front-wheel drive. Refer to «Parking brake cable - vehicles with front-wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-cable-vehicles-with)
2. Removing and installing on vehicles with all wheel drive. Refer to «Parking brake cable - vehicles with all wheel drive, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-cable-vehicles-with)
3. Adjusting parking brake. Refer to «Parking brake, adjusting»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-adjusting)

10 - Switch

1. For parking brake warning lamp

Parking brake cable - vehicles with front-wheel drive, removing and installing

Removing

Scheme 95

1. Remove switch mount with storage compartment and cover for rear center console.

Refer to 68 - INTERIOR EQUIPMENT

1. Release parking brake.

Scheme 96

1. Loosen adjustment nut (arrow) until the parking brake cable can be unhooked from the compensator.

1. Pry off clip -1- for parking brake cable.
2. Press brake lever -2- in direction of arrow and unhook brake cable -3-.

Scheme 97

1. Unclip parking brake cable from retainer on rear axle -arrow A- and unhook from retainers (arrows).

Scheme 98

1. Pull parking brake cable out from guide tube -1- in direction of (arrow).

Installing

Install in reverse sequence; note the following points

1. Slide parking brake cable into guide tube.

1. Press brake lever -2- in direction of arrow and attach parking brake cable.
2. Open clip -1- securing parking brake cable.

1. Clip parking brake cable into retainer on rear axle (arrow -A-).

Note. Clamping ring at parking brake cable must be positioned in center of clip.

1. Hook parking brake cable into retainers (arrows).
2. Hook parking brake cable into compensator.

1. Pretighten parking brake cable with adjustment nut (arrow).
2. Adjust parking brake. Refer to «Parking brake, adjusting»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-adjusting) .

Parking brake cable - vehicles with all wheel drive, removing and installing

Removing

1. Remove switch mount with storage compartment -1- and cover for rear center console -2-.

Refer to 68 - INTERIOR EQUIPMENT

1. Release parking brake.

1. Loosen adjustment nut (arrow) until the parking brake cable can be unhooked from the compensator.

1. Pry off clip -1- for parking brake cable.
2. Press brake lever -2- in direction of arrow and unhook brake cable -3-.

Scheme 99

1. Remove rubber grommet (arrow -A-) in trailing arm.
2. Unhook parking brake cable (arrow) from retainer and pull out of trailing arm in direction of (arrow).

1. Pull parking brake cable out from guide tube -1- in direction of (arrow).

Installing

Install in reverse sequence; note the following points

1. Slide parking brake cable into guide tube.

1. Press brake lever -2- in direction of (arrow) and attach parking brake cable.
2. Open clip -1- securing parking brake cable.

Scheme 100

1. Install rubber grommet (arrow -A-) in trailing arm.
2. Hook parking brake cable in retainer (arrow).
3. Hook parking brake cable into compensator.

1. Pretighten parking brake cable with adjustment nut (arrow).
2. Adjust parking brake. Refer to «Parking brake, adjusting»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__parking-brake-adjusting) .

Parking brake, adjusting

Note. A new adjustment is only necessary after replacing, parking brake cables, brake calipers and brake discs.

1. Remove switch mount with storage compartment -1- and cover for rear center console -2-.

Refer to 68 - INTERIOR EQUIPMENT

1. Parking brake lever in "rest/off" position. Tighten adjusting nut -arrow-.....

Scheme 101

1. .... until lever (arrow) lifts off the brake caliper stop.

1. The maximum permissible distance from the stop is 3 mm on either side.

1. Pull parking brake firmly three times and then release again.
2. Check that both wheels turn freely while parking brake lever is released.

Note. Due to the automatic rear wheel brake adjustment there is no requirement to adjust the parking brake after making new/initial adjustment.

Scheme 102

1 - Mounting bracket

1. From approx. 06.99 with collapsing support -Item 2- «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .
2. When installing a new mounting bracket with collapsing support on a vehicle with year of make prior to approx 06.99, the support must be cut off at the point indicated with an -arrow- there is no means of attaching.

2 - Collapsing support

3 - Nut - 28 Nm

1. Self-locking
2. Replace each time after removing

4 - Brake light switch

1. Removing and installing; adjusting (square housing). Refer to «Brake light switch (square housing), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-square-housing-removing)
2. Removing and installing; adjusting (round housing). Refer to «Brake light switch (round housing), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-round-housing-removing) and «Brake light switch, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-removing-and-installing)

5 - Accelerator pedal

6 - Bolt

7 - Brake pedal

1. Removing and installing. Refer to «Brake pedal, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pedal-removing-and-installing)
2. Separating from brake booster. Refer to «Separating brake pedal from brake booster»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__separating-brake-pedal-from-brake-booster)
3. Grease all bearings with polycarbamide grease, G 052 142 A2 before installing

8 - Pad

9 - Nut - 20 Nm

1. Self-locking
2. Replace each time after removing

10 - Mounting bushing

1. Grease all bearings with polycarbamide grease, G 052 142 A2 before installing

11 - Pivot pin

1. Grease all bearings with polycarbamide grease, G 052 142 A2, before installing

Brake pedal, removing and installing

Removing

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

Scheme 103

1. Unscrew bolts -1-.
2. Remove cover -A-.
3. Remove brake light switch (square housing). Refer to «Brake light switch (square housing), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-square-housing-removing) .
4. Remove brake light switch (round housing). Refer to «Brake light switch (round housing), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-round-housing-removing) and «Brake light switch, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-removing-and-installing) .

Scheme 104

1. Remove connecting plate between clutch pedal and brake pedal (arrows) on vehicles with manual transmission.
2. Unplug 6-pin connector on accelerator pedal module.
3. Separate brake pedal from brake booster. Refer to «Separating brake pedal from brake booster»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__separating-brake-pedal-from-brake-booster) .
4. Remove hex nut -Item 9- «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) and detach brake pedal.

Installing

Install in reverse sequence; note the following points

Note. Before installing, grease all bearings with polycarbamide grease, G 052 142 A2.

Scheme 105

1. Hold ball head of push rod in front of mounting and push brake pedal in direction of brake booster, so that the ball head locates audibly.

1. Install brake light switch (square housing). Refer to «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__installing) .
2. Install brake light switch (round housing). Refer to «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) and «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .

Tightening torque

1) Replace nuts

Separating brake pedal from brake booster

Special tools and equipment

Scheme 106

1. T 10006 Release tool

Separating

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

1. Remove brake light switch (square housing). Refer to «Brake light switch (square housing), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-square-housing-removing) .
2. Remove brake light switch (round housing). Refer to «Brake light switch (round housing), removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-round-housing-removing) and «Brake light switch, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-light-switch-removing-and-installing) .
3. Unplug electrical connectors from clutch pedal switch and from interlock switch.

1. Remove connecting plate between clutch pedal and brake pedal -arrows- on vehicles with manual transmission.

Scheme 107

1. Press brake pedal -1- in direction of brake booster and hold.
2. Insert release tool T 10006 as shown and pull toward driver's seat while providing support at brake pedal -1- (pedal must not be allowed to move to rear at this point). This presses retainer tabs -3- off ball head.
3. Pull both release tool T 10006 and brake pedal toward driver's seat (this pulls brake pedal off push rod ball head.

Note. For ease of illustration, Fig. shows separation of brake pedal from brake booster with pedal cluster removed.

Install in reverse sequence; note the following points

1. Hold push rod ball head in front of mounting and push brake pedal in direction of brake booster, so that the ball head audibly locates.
2. Install brake light switch (square housing). Refer to «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__installing) .
3. Install brake light switch (round housing). Refer to «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) and «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .

High-pressure and low-pressure test

Special tools and equipment

Scheme 108

1. VAG 1310 A

1. VAG 1869/2

Test requirement

1. Brake system (brake master cylinder, brake hoses, brake lines and brake calipers) tested for operation and tightness.

High-pressure test

1. Remove bleeder screw at one of the front brake calipers. Connect pressure gauge VAG 1310 A and bleed.
2. Insert brake pedal depressor VAG 1869/2 between brake pedal and driver's seat. Apply pressure to brake pedal until the gauge indicates a pressure of 50 bar. The test lasts for 45 seconds, during which time the pressure must not drop by more than 4 bar.

If the drop in pressure is greater, replace the hydraulic control unit.

Low-pressure test

1. Move the brake pedal depressor back until the pressure gauge indicates a pressure of 6 bar.
2. The test lasts for 3 minutes, during which time the pressure must not drop by more than 1 bar.

If the drop in pressure is greater, replace the hydraulic control unit.

Front brake caliper, servicing

Note. Replace complete repair kit when performing service work. New brake calipers are filled with brake fluid and pre-bled. Apply thin coat of assembly paste G 052 150 A2 to brake cylinder, piston and sealing ring.

Scheme 109

1 - Protective seal

2 - Bleed screw - 10 Nm

1. Apply thin coat of assembly paste G 052 150 A2 to threads before screwing in

3 - Cap

1. Insert in mounting bushing

4 - Guide pin - 28 Nm

5 - Mounting bushing

1. Insert into brake caliper housing

6 - Brake caliper housing

7 - Brake carrier

8 - Retaining spring

1. Insert both ends in the holes in brake caliper housing

9 - Seal

1. Do not damage when inserting piston
2. Removing and installing. Refer to «Front brake caliper piston, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__front-brake-caliper-piston-removing-and)

10 - Piston

1. Removing and installing. Refer to «Front brake caliper piston, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__front-brake-caliper-piston-removing-and)
2. Apply thin coat of assembly paste G 052 150 A2 to piston

11 - Protective seal

1. Pull outer sealing lip onto piston
2. Removing and installing. Refer to «Front brake caliper piston, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__front-brake-caliper-piston-removing-and)

Front brake caliper piston, removing and installing

Special tools and equipment

Scheme 110

1. 3409 Removal wedge
2. Piston resetting tool

Removing

Scheme 111

1. Force piston out of brake caliper housing using compressed air.

Note. Place a piece of wood in the recess to prevent damage to the piston.

Scheme 112

1. Remove seal using wedge 3409.

Note. Make sure when removing the surface of the cylinder is not damaged.

Installing

1. The surface of the piston and seal must only be cleaned with methylated spirits and then dried.
2. Apply thin coat of assembly paste G 052 150 A2 to piston and protective seal before installing.
3. Insert oil seal in brake caliper housing.

Scheme 113

1. Position outer sealing lip on piston.

Scheme 114

1. Using wedge 3409, insert the inner sealing lip into the grove in the cylinder.

Note. When doing this hold piston in front of caliper housing.

Scheme 115

1. Press piston into the brake caliper housing using piston resetting tool.

Note. The protective seal outer sealing lip will then locate in the piston groove.

Scheme 116

1. Install complete repair kit when performing service work.
2. New brake calipers are filled with brake fluid and pre-bled.
3. Apply thin coat of assembly paste G 052 150 A2 to brake cylinder, piston and seal.

1 - Dust cap

1. Install on bleeder valve

2 - Bleeder valve, 10 Nm

1. Grease lightly with assembly paste G 052 150 A2, before screwing in

3 - Caps

1. Insert in mounting bushing

4 - Guide pin, 25 Nm

5 - Mounting bushing

1. Insert into brake caliper housing

6 - Brake caliper housing

7 - Brake carrier

1. Bolt onto brake caliper housing

8 - Retaining spring

9 - Seal

1. Removing and installing. Refer to «Front brake caliper piston, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

10 - Piston

1. Removing and installing. Refer to «Front brake caliper piston, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Apply thin coat of assembly paste G 052 150 A2 to piston before installing

11 - Protective seal

1. Removing and installing. Refer to «Front brake caliper piston, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
2. Do not damage when inserting piston

Special tools and equipment

1. 3409 Removal wedge
2. Piston resetting tool

Removing

Scheme 117

1. Force piston out of brake caliper housing using compressed air.

Note. Place a piece of wood in the recess to prevent damaging the piston. You can only remove one piston at a time; hold the other piston in the caliper housing using the piston resetting tool.

Scheme 118

1. Remove protective seal from piston groove using wedge 3409.
2. Take out piston.

Note. Make sure that the surface of the cylinder is not damaged, when removing.

Scheme 119

1. Take out protective seal using wedge 3409.

Scheme 120

1. Use wedge 3409 to remove seal.

Note. Make sure that the surface of the cylinder is not damaged, when removing.

Installing

1. The surface of the piston and seal must be cleaned with methylated spirits only, and then dried.
2. Thinly coat piston and seal with assembly paste G 052 150 A2 before inserting.
3. Insert seal in brake caliper housing.

1. Position outer sealing lip of protective seal on piston.

Scheme 121

1. Insert the inner sealing lip into the grove in the cylinder, using wedge 3409.

Note. When doing this hold piston in front of caliper housing.

Scheme 122

1. Press piston into brake caliper housing as far as possible by hand.

Scheme 123

1. Press piston into brake caliper housing using piston resetting tool.

Note. The outer sealing lip of the protective seal will then locate in the piston groove.

Rear brake caliper, servicing

Note. Install complete repair kit when performing service work. New brake calipers are filled with brake fluid and pre-bled. Apply thin coat of assembly paste G 052 150 A2 to brake cylinder, piston and sealing ring. When performing repair work, always pre-bleed brake calipers accordingly, prior to installation in vehicle (without brake pads). Refer to Pre-bleeding brake caliper .

Scheme 124

1 - Bolt - 35 Nm

1. Self-locking
2. Replace each time after removing
3. When loosening and tightening counter-hold on guide pin

2 - Bleeder screw - 10 Nm

1. Apply thin coat of assembly paste G 052 150 A2 to threads before screwing in

3 - Protective seal

4 - Guide pins

1. Grease before pulling on protective cap

5 - Protective cap

1. Pull onto brake carrier and guide pin

6 - Brake carrier with guide pin and protective cap

1. Supplied as replacement part, assembled with sufficient grease on guide pins
2. If protective caps or guide pins are damaged, install repair kit. Use grease packet supplied to lubricate the guide pins.

7 - Protective cap

1. Pull outer sealing lip onto piston

8 - Piston with automatic adjustment

1. Removing and installing. Refer to «Rear brake caliper piston, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__rear-brake-caliper-piston-removing-and)
2. Apply thin coat of assembly paste G 052 150 A2 to piston

9 - Seal

1. Do not damage when inserting piston
2. Removing and installing. Refer to «Rear brake caliper piston, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__rear-brake-caliper-piston-removing-and)

10 - Brake caliper housing with parking brake cable lever

1. If a leak exists at the parking brake cable lever replace brake caliper housing
2. After repairing, pre-bleed caliper housing. Refer to «Pre-bleeding brake caliper»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

Rear brake caliper piston, removing and installing

Special tools and equipment

1. 3272 Piston compressing and extracting tool

1. 3409 Removal wedge
2. Bleeder container

1. Apply special tool 3272 together with 3272/1 to piston on brake caliper housing.
2. Screw piston out of brake caliper housing by turning the knurled wheel counter-clockwise.

Note. If piston is stiff, use a 13 mm open-ended wrench to be applied at appropriate flats (arrow).

Scheme 125

1. Remove seal using wedge 3409.

1. The surface of the piston and seal must be cleaned with methylated spirits and then dried.
2. Thinly coat piston and seal with assembly paste G 052 150 A2 before inserting.
3. Insert oil seal in brake caliper housing.

1. Place protective seal with the outer sealing lip on the piston.

Scheme 126

1. Using wedge 3409, insert the inner sealing lip into the grove in the cylinder.

Note. When doing this hold piston in front of caliper housing.

1. Apply special tool 3272 together with 3272/1 to piston on brake caliper housing.
2. Screw piston into housing by turning knurled wheel clockwise.

Note. Adjusting piston with a normal resetting tool destroys automatic adjuster in brake caliper.

1. Install brake pads.

Scheme 127

1. Open bleeder screw (arrow -A- ) and use a standard bleeder bottle to fill with brake fluid until bubble-free brake fluid flows from the threaded hole (arrow -B-) (brake hose connection). Close bleeder screw.

Note. Position brake caliper as illustrated to pre-bleed.

System must first be pre-bled when one chamber in the brake fluid reservoir is completely empty (e.g. brake system leaking). Refer to Pre-bleeding of brake system .

Afterward the hydraulic unit must be bled with vehicle diagnostic, testing and information system VAS 5051 in function "04 - Basic setting". Refer to Brake fluid reservoir is empty, bleeding brake system .

When using a brake filler and bleeder unit (such as VAS 5234) to replenish the brake fluid, make sure that filling pressure does not exceed 1 bar.

If the filling pressure exceeds 1 bar, a hydraulically controlled change-over valve (which is required for the EDL function) prevents unrestricted flushing of the EDL-related parts of the hydraulic unit. If this is the case, it may not be possible to bleed the system properly.

For this reason the brake fluid pressure must be reduced to 1 bar on the brake filling and bleeding appliance.

Refer to Operating instructions for VAS 5234

Note. Use only new brake fluid with part No. B 000 700 A. (Container contents available from 0.25 to 30 liters). Rinse off any brake fluid spillages using plenty of water.

Special tools and equipment

1. Brake filler and bleeder unit VAS 5234

Work sequence

1. Connect brake filler and bleeder unit VAS 5234.

1. Remove protective cap from bleeder screw on brake caliper and attach bleeder bottle hose to bleeder screw.

Bleeding sequence

1 - Left front brake caliper

2 - Right front brake caliper

3 - Left rear brake caliper

4 - Right rear brake caliper

1. Leave bleeder screw open, with bleeder bottle hose connected, until brake fluid emerges out of the bleeder screw clear and free from air bubbles.
2. Build up pressure in brake system to aid bleeding by pumping pedal five times.
3. Tighten bleeder screw to 10 Nm. Detach hose and install protective cap on bleeder screw.
4. Repeat procedure on remaining brake calipers in the specified bleeding sequence.

1. Top off fluid level in reservoir to "MAX" mark (according to degree of pad wear) and close reservoir cap.
2. Start engine and test pedal travel and pedal pressure.
3. If the pedal travel is excessive, check brake system for leaks or repeat bleeding procedure.

A test drive must be carried out after bleeding brakes. When doing this an ABS-controlled brake application on all four wheels must be performed at least once.

Changing brake fluid

Refer to 01 MAINTENANCE

Note. Make sure there is always sufficient brake fluid in the reservoir.

1. Remove protective cap from bleeder screw on brake caliper and attach bleeder bottle hose to bleeder screw.

Bleeding sequence. Refer to Bleeding sequence

1. Build-up brake pressure in brake system by pumping the brake pedal.

Note. Pump the pedal slowly to ensure bubble-free flow.

1. Hold brake pedal down after building up pressure.
2. Open bleeder screw with bleeder bottle hose attached until pressure drops (pedal drops).
3. With brake pedal held down, close bleeder screw.
4. Release brake pedal and wait for approx. 2 seconds to enable brake fluid to run from brake fluid reservoir.

1. Repeat operation until brake fluid emerges clear and free from air bubbles.
2. Tighten bleeder screw to 10 Nm, detach bleed hose and install protective cap on bleeder screw.
3. Repeat procedure at the remaining brake calipers in the specified bleeding sequence.

Note. If one chamber of brake fluid reservoir has run completely empty (e.g. due to leak in brake system), brake system must be pre-bled. Refer to Pre-bleeding of brake system .

1. Top off fluid level in reservoir to "Max" mark (according to degree of pad wear) and close reservoir cap.
2. Start engine and check pedal travel and brake pedal pressure.
3. If the pedal travel is excessive, check brake system for leaks or repeat bleeding procedure.

Changing brake fluid

Refer to 01 MAINTENANCE

Special tools and equipment

1. Brake filler and bleeder unit VAS 5234

Scheme 128

1. Vehicle diagnostic, testing and information system VAS 5051 and VAS 5051/1

When using a brake system filling and bleeding appliance (such as VAS 5234) to replenish the brake fluid, make sure that filling pressure does not exceed 1 bar.

If the filling pressure exceeds 1 bar, a hydraulically controlled change-over valve (which is required for the EDL function) prevents unrestricted flushing of the EDL-related parts of the hydraulic unit. If this is the case, it may not be possible to bleed the system properly.

For this reason the brake fluid pressure must be reduced to 1 bar on the brake filler and bleeding unit.

Refer to Operating instructions for VAS 5234.

Filler and bleeder unit V.A.G 1238/B is not suitable for bleeding the brake system by using the "Basic setting" function.

If only filler and bleeder unit V.A.G 1238/B is available, then switch unit on/off to ensure that sufficient brake fluid is always present in reservoir.

Requirement for test

1. Connect vehicle diagnostic, testing and information system VAS 5051, select "Vehicle self-diagnosis" and vehicle system "03 - Brake electronics".

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. Connect brake filler and bleeder unit VAS 5234.
2. Open bleeder screws in the specified sequence and pre-bleed brake calipers.

1 - Bleed left front and right front brake calipers simultaneously.

2 - Bleed left rear and right rear brake calipers simultaneously.

1. Leave the bleeder screw open, with brake fluid hose connected, until brake fluid free from air bubbles comes out of the bleeder screw.

Scheme 129

Display on VAS 5051

1. Select the diagnosis function "04 - Basic settings" from the menu -1-.

Note. During the next steps the ABS warning lamp flashes.

Scheme 130

Display on VAS 5051

1 - Enter display group

1. Using the keypad -2-, enter "001" to select Display group 001 and confirm entry with Q key.

Scheme 131

Display on VAS 5051

1 - System in basic setting

2 - Display group 1

3 - Press pedal and hold in position...

1. Operate pedal with substantial foot pressure and hold.

1. Pedal drops, hydraulic pump starts up, pedal returns

Display on VAS 5051

3 - Release pedal; FR/FL bleed screws OPEN <>

1. Release pedal, open front bleeder screws.
2. Press the [Back Arrow] button to advance to Display group 002.

Display on VAS 5051

1 - System in basic setting

2 - Display group 2

3 - Please wait (10 sec.)

1. Wait for 10 seconds.

1. Hydraulic pump starts up briefly

Display on VAS 5051

3 - Press pedal 10X; bleed screws CLOSED <>

1. Press pedal 10 times, close front bleed screws.
2. Press the [Back Arrow] button to advance to display group 003.

Display on VAS 5051

1 - System in basic setting

2 - Display group 3

3 - Press pedal and hold in position...

1. Repeat bleeding procedure as described above
2. Press the [Back Arrow] button several times to advance to the next display groups until display group 17 is indicated.

Display on VAS 5051

1 - System in basic setting

2 - Display group 17

3 - Partial bleeding over...

1. Press the <-- button to exit from diagnosis function "04 - Basic settings".

Display on VAS 5051

1. Select diagnosis function "06 - End output" from the menu -1-.

Scheme 132

Display on VAS 5051

1. When this display appears, switch off ignition and unplug diagnostic connector.
2. Now perform bleeding of brake system. Refer to «ABS/ESP ITT Mark 20, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .

System must first be pre-bled when one chamber in the brake fluid reservoir is completely empty (e.g. brake system leaking). Refer to Pre-bleeding .

The hydraulic unit must be bled with vehicle diagnostic, testing and information system VAS 5051 in function "04 - Basic setting". Refer to Bleeding brake system when brake fluid reservoir is empty .

When using a brake filler and bleeder unit (such as VAS 5234) to replenish the brake fluid, make sure that filling pressure does not exceed 1 bar.

If the filling pressure exceeds 1 bar, a hydraulically controlled change-over valve (which is required for the EDL function) prevents unrestricted flushing of the EDL-related parts of the hydraulic unit. If this is the case, it may not be possible to bleed the system properly.

For this reason the brake fluid pressure must be reduced to 1 bar on the brake filling and bleeding appliance.

Refer to Operating instructions for VAS 5234

Note. Use only new brake fluid with part No. B 000 700 A. (Container contents available from 0.25 to 30 liters). Rinse off brake fluid spillages, using plenty of water.

Special tools and equipment

1. VAS 5234 Brake filler and bleeder unit

1. Connect brake filler and bleeder unit VAS 5234.
2. Remove protective cap from bleeder screw on brake caliper and attach bleeder bottle hose to bleeder screw.

Bleed sequence

1 - Left front brake caliper

2 - Right front brake caliper

3 - Left rear brake caliper

4 - Right rear brake caliper

1. Leave bleeder screw open, with bleeder bottle hose connected, until brake fluid emerges out of the bleeder screw clear and free from air bubbles.
2. Build up pressure in brake system to aid bleeding by pumping pedal five times.
3. Tighten bleeder screw to 10 Nm. Detach hose and install protective cap on bleeder screw.
4. Repeat procedure on remaining brake calipers in the specified bleeding sequence.

1. Top off fluid level in reservoir to "MAX" mark (according to degree of pad wear) and close reservoir cap.
2. Start engine and check brake pedal travel and pressure.
3. If the pedal travel is excessive, check brake system for leaks or repeat bleeding procedure.

A zero compensation of brake pressure senders must be performed after bleeding brake system.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

A test drive must be carried out after bleeding brakes. When doing this an ABS-controlled brake application on all four wheels must be performed at least once.

Refer to 01 MAINTENANCE

Note. Make sure there is always sufficient brake fluid in the reservoir.

1. Remove protective cap from bleeder screw on brake caliper and attach bleeder bottle hose to bleed screw.

Bleeding sequence. Refer to Bleed sequence

1. Build-up brake pressure in brake system by pumping the brake pedal.

Note. Pump the pedal slowly to ensure bubble-free flow.

1. Hold brake pedal down after building up pressure.
2. Open bleeder screw with bleeder bottle hose attached until pressure drops (pedal drops).
3. With brake pedal held down, close bleeder screw.
4. Release brake pedal and wait for approx. 2 seconds to enable brake fluid to run from brake fluid reservoir.

1. Repeat operation until brake fluid emerges clear and free from air bubbles.
2. Tighten bleeder screw to 10 Nm, detach bleeder hose and install protective cap on bleeder screw.
3. Repeat procedure at the remaining brake calipers in the specified bleeding sequence.

Note. If one chamber of brake fluid reservoir has run completely empty (e.g. due to leak in brake system), brake system must be pre-bled. Refer to Pre-bleeding .

1. Top off fluid level in reservoir to "Max" mark (according to degree of pad wear) and close reservoir cap.
2. Start engine and check brake pedal travel and pressure.
3. If the pedal travel is excessive, check brake system for leaks or repeat bleeding procedure.

Changing brake fluid

Refer to 01 MAINTENANCE

Special tools and equipment

1. Brake filler and bleed unit VAS 5234

1. Vehicle diagnostic, testing and information system VAS 5051 and VAS 5051/1

When using a brake system filling and bleeding appliance (such as VAS 5234) to replenish the brake fluid, make sure that filling pressure does not exceed 1 bar.

If the filling pressure exceeds 1 bar, a hydraulically controlled change-over valve (which is required for the EDL function) prevents unrestricted flushing of the EDL-related parts of the hydraulic unit. If this is the case, it may not be possible to bleed the system properly.

For this reason the brake fluid pressure must be reduced to 1 bar on the brake filling and bleeding appliance.

Refer to Operating instructions for VAS 5234

Filler and bleeder unit VAG 1238/B is not suitable for bleeding the brake system by using the "Basic setting" function.

If only filler and bleeder unit VAG 1238/B is available, then switch unit on/off to ensure that sufficient brake fluid is always present in reservoir.

Requirement for test

1. Connect vehicle diagnostic, testing and information system VAS 5051, select "Vehicle self-diagnosis" and vehicle system "03 - Brake electronics".

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Pre-bleeding

1. Connect brake filler and bleeder unit VAS 5234.
2. Open bleeder screws in the specified sequence and pre-bleed brake calipers.

1 - Bleed left front and right front brake calipers simultaneously.

2 - Bleed left rear and right rear brake calipers simultaneously.

1. Leave the bleeder screw open, with brake fluid hose connected, until brake fluid free from air bubbles comes out of the bleeder screw.

Bleeding

Display on VAS 5051

1. Select the diagnosis function "04 - Basic settings" from the menu -1-.

Note. During the next steps the ABS warning lamp flashes.

Display on VAS 5051

1 - Enter display group

1. Using the keypad -2-, enter "001" to select Display group 001 and confirm entry with Q key.

Display on VAS 5051

1 - System in basic setting

2 - Display group 1

3 - Press pedal and hold in position.

1. Operate pedal with substantial foot pressure and hold.

1. Pedal drops, hydraulic pump starts up, pedal returns

Display on VAS 5051

3 - Release pedal; FR/FL bleed screws OPEN <>

1. Release pedal, open front bleeder screws.
2. Press the [Back Arrow] button to advance to Display group 002.

Display on VAS 5051

1 - System in basic setting

2 - Display group 2

3 - Please wait.. (10 sec.)

1. Wait for 10 seconds.

1. Hydraulic pump starts up briefly

Display on VAS 5051

3 - Press pedal 10X; bleed screws CLOSED <>

1. Press pedal 10 times, close front bleeder screws.
2. Press the [Back Arrow] button to advance to display group 003.

Display on VAS 5051

1 - System in basic setting

2 - Display group 3

3 - Press pedal and hold in position.

1. Repeat bleeding procedure as specified earlier.
2. Press the [Back Arrow] button several times to advance to the next display groups until display group 17 is indicated.

Display on VAS 5051

1 - System in basic setting

2 - Display group 17

3 - Partial bleeding over...

1. Press the <-- button to exit from diagnosis function "04 - Basic settings".

Display on VAS 5051

1. Select diagnosis function "06 - End output" from the menu -1-.

Display on VAS 5051

1. When this display appears, switch off ignition and unplug diagnostic connector.
2. Now perform bleeding of brake system. Refer to «Bleeding brake system using brake filler and bleeder unit VAS 5234»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .

Vacuum servo pump

From 2001 models on, certain gasoline engine versions in conjunction with automatic transmission are equipped with an electric vacuum pump to boost the vacuum supplied to the brake servo.

Test procedure

1. Drive vehicle onto lifting platform, switch engine off.
2. Start engine.

1. While the engine is being started the brake system vacuum pump -V192- (located on subframe in front of steering box, left side) should run briefly.

1. A second person has to touch the pump by hand to check whether it is running.

If brake system vacuum pump -V192- does not run

1. Check fault memory in the engine control module

Refer to

1. «01 ON BOARD DIAGNOSTIC (OBD)»(/audi/tt/8n-1998-2003/remont/fuel-system/#18l-4-cyl-5v-turbo-fuel-injection-ignition-engine-codes-amu) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AMU
2. «01 ON BOARD DIAGNOSTIC (OBD)»(/audi/tt/8n-1998-2003/remont/fuel-system/#18l-4-cyl-5v-turbo-fuel-injection-ignition-engine-codes-atc) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): ATC
3. «01 ON BOARD DIAGNOSTIC (OBD)»(ref-276272-S12227258552008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AWP
4. «01 ON BOARD DIAGNOSTIC (OBD)»(ref-276273-S13756956692008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): BEA
5. «01 - ON BOARD DIAGNOSTIC (OBD)»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-generic-scan-tool-engine-codes-amu-bea-atc-awp) for 1.8 LITER 4-CYL. 5V TURBO GENERIC SCAN TOOL ENGINE CODE(S): AMU, BEA, ATC, AWP

There is no provision for repairing the brake system vacuum pump -V192-. The pump must be replaced if defective.

Removing

1. Unscrew hex bolt securing guard plate.

Scheme 133

1. Unscrew bolts -1- on bracket for vacuum pump on left side of subframe.
2. Disconnect vacuum hose (arrow) from vacuum pump.
3. Unplug electrical connector.
4. Take out brake system vacuum pump -V192-.

Scheme 134

1. To remove bracket (arrow), unscrew nut -2- from bolt -1-.
2. Remove bolt -4- and detach bracket.
3. To disassemble bracket further, remove bolts -3-.

Installing

Installation is performed in reverse sequence.

Tightening torques

Scheme 135

Note. Brake master cylinder and brake booster can be replaced as individual components. The Fig. shows the brake booster of the ABS/ESP Mk 20 system. With the ABS/ESP Mk 60 system the components -Item 2, 14 and 15- as well as the magnetic coil for brake pressure, in brake booster -N247- on the brake booster and the brake pressure release solenoid -F84- are missing.

1 - Brake booster

1. Functional check

1. With engine switched off, depress brake pedal firmly several times (to exhaust the vacuum in the unit).
2. Now depress brake pedal with average foot pressure, hold and start engine. If the booster unit is working properly, the pedal will give slightly under foot (booster assistance becomes effective).

1. The vacuum required is taken from the intake manifold.
2. If loud suction noise is heard on braking, check proper positioning of inner boot. Refer to -Item 20- «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. Detaching from brake pedal. Refer to «Separating brake pedal from brake booster»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__separating-brake-pedal-from-brake-booster)
4. Removing and installing. Refer to «Brake booster, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-booster-removing-and-installing)

2 - Bracket

1. Used to mount the electrical connector -Item 14- «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

3 - Cap

1. With integrated float and brake fluid warning indicator

4 - Brake fluid reservoir

1. Moisten with brake fluid and press into sealing plugs in brake master cylinder
2. Locate with retaining pin -Item 6- «Exploded view»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)
3. With warning contact for brake fluid level (phased introduction)
4. Remove brake fluid reservoir to replace warning contact

5 - Sealing plug

1. Moisten with brake fluid and press into brake master cylinder
2. Press brake fluid reservoir into sealing plugs.

6 - Retaining pin

1. For brake fluid reservoir

7 - Brake master cylinder

1. Removing and installing. Refer to «Brake master cylinder, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-master-cylinder-removing-and-installing)

8 - Mounting plate

1. Different versions available
2. Application

9 - Nut - 4 Nm

1. Self-locking
2. Replacing each time after removing

10 - Heat shield

1. Application

11 - Sensor -2- for brake pressure -G214

1. Removing and installing. Refer to «Brake pressure sensors, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pressure-sensors-removing-and-installing)

12 - Sender 1 for brake booster -G201

1. Removing and installing. Refer to «Brake pressure sensors, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pressure-sensors-removing-and-installing)

13 - Seal

1. Always replace

14 - Electrical connector

15 - Electrical wire

16 - Vacuum line

1. With non-return valve
2. Check non-return valve. See «Checking non-return valve»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

17 - Sealing plug

18 - Gasket

1. For brake booster

19 - Nut - 28 Nm

1. Self-locking
2. Replacing each time after removing

20 - Boot

1. If unusually loud suction noise is heard on braking, check proper positioning of inner boot. See «Checking inner boot of brake booster»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system)

Scheme 136

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

1. Check whether bellows have slipped out of annular groove as shown in this figure.
2. Remove brake-pedal mounting bracket to insert boot. Refer to «Brake pedal, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-pedal-removing-and-installing)

Scheme 137

1. Non-return valve -A- should be open and allow passage of air in direction of (arrow) (blow into valve).
2. Valve should remain closed in opposite direction and not allow air to pass.

Note. Pay attention to correct installation position.

Brake master cylinder, removing and installing

Special tools and equipment

Scheme 138

1. Hose clamps 3094

1. Brake filler and bleeder unit VAS 5234
2. Repair kit

1 - Valve dome transportation protection (plastic foam)

2 - M10 sealing plugs for brake lines and threaded holes

3 - M12 sealing plugs for brake lines and threaded holes

1. Remove engine cover panel where necessary for access to components.

1. Remove screws (arrows).
2. Remove forward left-hand cover panel.

1. If installed, disconnect secondary air intake hose -1- from air cleaner.
2. Disconnect air hose -2- from mass air flow sensor.
3. Unplug connector -3- from mass air flow sensor.
4. Unscrew bolts -4- and -5-.

1. Remove air cleaner housing.
2. Lay out sufficient lint-free cloths in area below brake master cylinder to catch escaping brake fluid.
3. Draw off as much brake fluid as possible from brake fluid reservoir using brake filler and bleeder unit VAS 5234 or extraction unit VAG 1869/4.
4. Clamp off clutch master cylinder supply hose with hose clamp 3094.

1. Pull off clutch master cylinder supply hose.
2. Pull connector off float warning indicator sender if part of original equipment.

1. Pull connectors (arrows) off brake pressure sensors -a- and -b-.
2. Disconnect brake lines on brake master cylinder and seal brake lines with plugs from repair kit.
3. Remove securing nuts from brake master cylinder.
4. Remove heat shield with retainer plate, if part of original equipment.

1. Remove brake master cylinder from brake booster.

Install in reverse sequence; note the following points

1. Replace sealing ring between brake master cylinder and brake booster.
2. When inserting brake master cylinder, make sure that push rod in brake booster is correctly positioned.
3. Apply slight pressure to the brake pedal; this makes it easier to guide brake master cylinder onto pushrod.
4. Bleed brake system: ABS/ESP Mark 20. Refer to «ABS/ESP ITT Mark 20, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) , ABS/ESP Mark 60. Refer to «ITT ABS/ESP Mark 60, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .

1. Bleed hydraulic system for clutch

Refer to 30 CLUTCH for 5 AND 6 SPD. MANUAL TRANSMISSION 02M, 02Y ALL WHEEL DRIVE or 30 CLUTCH for 5 SPD. MANUAL TRANSMISSION 02J FRONT WHEEL DRIVE

1. Initiate basic settings for brake pressure senders.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. Perform ESP road test on vehicles with ABS/ESP Mark 60 system.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Tightening torques

1) Replace nuts

Brake booster, removing and installing

Removing

1. Release brake booster vacuum by operating the brake pedal several times.
2. Remove brake master cylinder. Refer to «Brake master cylinder, removing and installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__brake-master-cylinder-removing-and-installing) .
3. Pull vacuum hose off brake booster unit.
4. Disconnect electrical connector from brake booster if part of original equipment.

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT

1. Remove bolts -1-.
2. Remove cover -A-.
3. Separate brake pedal from brake booster. Refer to «Separating brake pedal from brake booster»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system__separating-brake-pedal-from-brake-booster) .

Scheme 139

1. Remove nuts (arrows).
2. Remove brake booster.

Installing

Install in reverse sequence; note the following points

1. Mount brake pedal on brake booster. Refer to «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .
2. Install brake master cylinder. Refer to «Installing»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .
3. Bleed brake system: ABS/ESP Mark 20. Refer to «ABS/ESP ITT Mark 20, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) , ABS/ESP Mark 60. Refer to «ITT ABS/ESP Mark 60, bleeding brake system»(/audi/tt/8n-1998-2003/remont/anti-locktraction-control/#brake-system) .
4. Bleed hydraulic system for clutch

Refer to 30 CLUTCH for 5 AND 6 SPD. MANUAL TRANSMISSION 02M, 02Y ALL WHEEL DRIVE or 30 CLUTCH for 5 SPD. MANUAL TRANSMISSION 02J FRONT WHEEL DRIVE

1. Initiate basic settings for brake pressure senders.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. Perform ESP road test on vehicles with ABS/ESP Mark 60 system.

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

Tightening torque

1) Replace nuts

Brake lines and hoses, removing and installing

The following section show different installation positions and lists tightening torques for brake lines and hoses.

Scheme 140

Brake lines at brake master cylinder/hydraulic unit; ITT Mark 20

1 - Brake line to brake master cylinder - 14 Nm

2 - Brake line to hydraulic unit - 14 Nm

Scheme 141

Brake lines at brake master cylinder/hydraulic unit; ITT Mark 60

1 - Tightening torque 14 Nm

2 - Tightening torque 24 Nm

3 - Tightening torque 8 Nm

4- Tightening torque 20 Nm

Scheme 142

Brake lines/hoses at front wheels - Vehicles with front-wheel drive

1 - Banjo bolt - 35 Nm

2 - Brake line - 14 Nm

3 - Retaining clip

4 - Brake hose

Scheme 143

Brake lines/hoses at front wheels - Vehicles with all wheel drive

1 - Banjo bolt - 35 Nm

2 - Brake line - 14 Nm

3 - Retaining clip

4 - Heat shield

[small diamond] Mounting to suspension strut see illustration below.

Scheme 144

Brake hose mounting on suspension strut - Vehicles with front-wheel drive

1 - Clamp

2 - Bolt - 9 Nm

3 - Heat shield

4 - Brake hose

5 - Retaining clip

Scheme 145

Brake lines/hoses at front wheels - Vehicles with 2FN brake system

1 - Hex bolt - 8 Nm

2 - Bracket

3 - Brake line

4 - Brake caliper

Scheme 146

Brake lines/hoses at brake caliper - Vehicles with 2FN brake system

1 - Brake hose

Connections going to caliper must point inwards after installing brake hose in wheel housing (arrow).

2 - Brake caliper

Union nut on brake hose is applied by hand.

Scheme 147

Brake line/hoses at rear wheels - Vehicles with front-wheel drive

1 - Brake hose

2 - Brake line - 14 Nm

3 - Bracket

4 - Retaining clip

Scheme 148

Brake hose mounting on brake caliper - Vehicles with front-wheel drive

1 - Banjo bolt - 38 Nm

Always replace brake line/hose with banjo bolt after unbolting banjo bolt.

2 - Brake hose

Scheme 149

Brake line/hoses at rear wheels - Vehicles with all wheel drive

1 - Bracket

2 - Brake hose

3 - Brake line - 14 Nm

4 - Retaining clip

Scheme 150

Brake line/angled sealing element mounting on brake caliper - Vehicles with all wheel drive

1 - Brake line - 14 Nm

2 - Angled sealing element

3 - Banjo bolt - 38 Nm

Always replace sealing element and banjo bolt after unbolting banjo bolt.

Scheme 151

Brake line connection

1. Counterhold union nut -1- when tightening banjo bolt -2-.

1. Tightening torque: 14 Nm

Brake hose connection with anti-twist element

1. Make sure that the groove in the ring connection of the brake hose is installed in the locating lug (arrow).

See also:
• 01 ON BOARD DIAGNOSTIC (OBD)
• 42 REAR SUSPENSION
• 68 - INTERIOR EQUIPMENT
• 30 CLUTCH
• 30 CLUTCH
• 66 EXTERIOR EQUIPMENT
• 01 MAINTENANCE
• 01 ON BOARD DIAGNOSTIC (OBD)
• 01 ON BOARD DIAGNOSTIC (OBD)
• 01 - ON BOARD DIAGNOSTIC (OBD)
• ABS/ESP ITT Mark 20, bleeding brake system
• Speed sensor, removing and installing
• Brake light switch (square housing), removing and installing
• Brake light switch (round housing), removing and installing
• Rotor, checking
• ABS wheel speed sensor, removing and installing
• ABS control module and hydraulic unit, removing and installing
• Longitudinal acceleration sensor -G251-, removing and installing
• Brake pressure sensors, removing and installing
• Sensor for transverse acceleration -G200- and Sender for rotation rate -G202-, removing and installing
• Steering angle sensor -G85-, removing and installing
• Wheel speed sensor wire, replacing
• Speed sensor wire, replacing
• Brake pads - vehicles with front-wheel drive, removing and installing
• Brake light switch, removing and installing
• Control module and hydraulic unit, removing and installing
• Longitudinal acceleration sensor -G251- (vehicles up to approx. 08.01), removing and installing
• ESP sensor unit -G419-, removing and installing
• ABS wheel speed sensor wire, replacing
• Front brake, servicing
• Brake pads - Front brakes FN 3, removing and installing
• Brake caliper - Front brakes FN 3, removing and installing
• Brake pads, removing and installing
• Parking brake cable - vehicles with front-wheel drive, removing and installing
• Parking brake, adjusting
• Brake caliper - vehicles with front-wheel drive, removing and installing
• Rear brake caliper, servicing
• Brake caliper - vehicles with all wheel drive, removing and installing
• Brake pads - vehicles with all wheel drive, removing and installing
• Brake pedal, removing and installing
• Separating brake pedal from brake booster
• Installing
• Front brake caliper piston, removing and installing
• Rear brake caliper piston, removing and installing
• Bleeding sequence
• Pre-bleeding
• Bleed sequence
• Brake booster, removing and installing
• Brake master cylinder, removing and installing