Antilock Brake System Audi A8 D2

General notes

Note. Before carrying out repairs, determine malfunction cause using On Board Diagnostic (OBD). See ON BOARD DIAGNOSTIC (OBD) . Only use parts in their original packing. Only unpack replacement parts immediately prior to installation. Only use lint-free cloths. 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. Absolute cleanliness is required when working on the anti-lock brake system. Do not use any products which contain mineral oil, such as oils, greases etc. Make sure that brake fluid does not enter harness connectors. Bleed brake system if connections in system have been opened (e.g. using VAS 5234 brake filler and bleeder unit). See BLEEDING BRAKE SYSTEM . When working with brake fluid, observe relevant safety precautions and notes. Place parts that have been removed on a clean surface and cover. Carefully cover opened components or seal, if repairs are not carried out immediately. (use sealing plugs from repair kit 1 H0 698 311 A) Do not work with compressed air and do not move vehicle while the system is open. 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).

Road testing vehicle

1. Some DTCs are only recognized by the 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.

Before beginning

Check brake system (master cylinder, brake hoses, brake lines and brake calipers) for function and proper sealing (must be free of leaks).

High-pressure test

1. Remove bleeder screw at one front brake caliper. Connect VAG1310 or VAG1310a brake pressure gauge and bleed.
2. Insert brake pedal depressor between brake pedal and driver's seat. Apply pressure to brake pedal until gauge indicates positive pressure of 50 bar (725 psi). Pressure must not drop by more than 4 bar (58 psi) during test period of 45 seconds. If drop in pressure exceeds specification: replace ABS hydraulic unit.

Scheme 1

Low-pressure test

1. Move brake pedal depressor back until pressure gauge indicates pressure of 6 bar (87 ft lb).
2. Pressure must not drop by more than 1 bar (14.5 psi) during test period of 3 minutes.

If drop in pressure exceeds specification: replace ABS hydraulic unit.

ABS/ESP, component overview

The following list pertains to (Scheme 2).

1. Hydraulic pump for traction control -V156- for ESP
2. Sender 1 for brake booster -G201- in driving dynamic control - pump for ESP
3. ABS return flow pump relay -J105- Bosch 5.3
4. ABS Solenoid Valve Relay -J106- Bosch 5.3
5. ABS Hydraulic Unit -N55- with ABS control module (w/EDL) -J104
6. ABS Control Module (w/EDL) -J104- Bosch 5.0 Installed position in instrument cluster
7. Brake fluid level warning switch -F34
8. Rotor for right front ABS wheel speed sensor Checking, see «ABS WHEEL SPEED SENSOR ROTOR, CHECKING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__abs-wheel-speed-sensor-rotor-checking) , and «AXLE SHAFTS»(/audi/a8/d2-1994-1999/remont/axle-shafts/#axle-shafts) and «SUSPENSION - FRONT»(/audi/a8/d2-1994-1999/remont/suspension-front/#suspension-front)
9. Right front ABS wheel speed sensor -G45- Removing and installing, see «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
10. ABS Control Module (w/EDL) -J104- for ESP Installed position in instrument cluster
11. Steering Angle Sensor -G85- for ESP Installation location: installed on steering column Removing and installing See «STEERING»(/audi/a8/d2-1994-1999/remont/electronic-steering/#steering) .
12. Anti-Slip Control Switch -E132- Installed position at center console
13. Steering angle sensor -G85- In one housing with airbag spiral spring Removing and installing, see «STEERING ANGLE SENSOR -G85-, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__steering-angle-sensor-g85-removing-and)
14. Parking brake warning light switch -F9- Installed position at parking brake assembly
15. Rotor for right rear ABS wheel speed sensor Rotor is welded to wheel hub. Removing and installing See «SUSPENSION - REAR»(/audi/a8/d2-1994-1999/remont/suspension-rear/#suspension-rear) .
16. Right rear ABS wheel speed sensor -G44- Removing and installing, see «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
17. Left rear ABS wheel speed sensor -G46- Removing and installing, see «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
18. Rotor for left rear ABS wheel speed sensor Checking, see «ABS WHEEL SPEED SENSOR ROTOR, CHECKING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system) Rotor is welded to wheel hub. Removing and installing See «SUSPENSION - REAR»(/audi/a8/d2-1994-1999/remont/suspension-rear/#suspension-rear) .
19. Sensor for transverse acceleration -G200- New version with sensor for rotation rate -G202- in one housing Removing and installing, see «SENSOR FOR TRANSVERSE ACCELERATION -G200- AND SENDER FOR ROTATION RATE -G202-, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
20. Sender for rotation rate -G202- Removing and installing, see «SENSOR FOR TRANSVERSE ACCELERATION -G200- AND SENDER FOR ROTATION RATE -G202-, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
21. ABS return flow pump relay -J105- only for Bosch 5.3 Installed position at fuse box
22. ABS Solenoid Valve Relay -J106- 5.3 Bosch 5.3
23. Warning light for brake system -K118-, malfunction symbol Installed position in instrument cluster in Driver Information System (DIS)
24. ABS warning light -K47- Installed position in instrument cluster
25. Parking brake indicator light -K14- Installed position in instrument cluster
26. Traction control indicator light -K86- Installed position in instrument cluster
27. Brake light switch -F- Removing and installing brake light switch, see «BRAKE LIGHT SWITCH, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
28. Rotor for front left ABS wheel speed sensor Checking, see «ABS WHEEL SPEED SENSOR ROTOR, CHECKING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__abs-wheel-speed-sensor-rotor-checking) See «SUSPENSION - FRONT»(/audi/a8/d2-1994-1999/remont/suspension-front/#suspension-front) and «AXLE SHAFTS»(/audi/a8/d2-1994-1999/remont/axle-shafts/#axle-shafts) .
29. Left front ABS wheel speed sensor -G47- Removing and installing, see «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)

Hydraulic unit and brake lines

Brake line tightening torque: 15 Nm.

The following list pertains to (Scheme 3).

1. Bolt 5 Nm
2. Cover
3. ABS solenoid valve relay
4. ABS return flow pump relay
5. ABS hydraulic unit 5.0 Different versions, see «BRAKE LINE CONNECTIONS AT THE HYDRAULIC UNIT, ABS 5.0»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__brake-line-connections-at-the-hydraulic) and «BRAKE LINE CONNECTIONS AT THE HYDRAULIC UNIT, ABS 5.0»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system) No repair work is permitted at the hydraulic unit except for replacement of both relays. Do not remove screws. The hydraulic unit is prevented before delivery as a replacement part. See Caution before beginning repairs on electrical system. See «ANTI-LOCK BRAKE SYSTEM (ABS) BOSCH 5.0»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system) . Removing and installing the hydraulic unit Disconnect Ground (GND) strap from battery Remove front half of front right wheelhousing liner. Disconnect brake lines and immediately seal connections with plugs Bolt a new hydraulic unit into bracket - 35 -. Brake lines must be connected according to the marks on the hydraulic unit. Hydraulic unit/line connections/rear side, see «BRAKE LINE CONNECTIONS AT THE HYDRAULIC UNIT, ABS 5.0»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__brake-line-connections-at-the-hydraulic) and «BRAKE LINE CONNECTIONS AT THE HYDRAULIC UNIT, ABS 5.0»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system) Bleed brake system. See «BLEEDING BRAKE SYSTEM»(/audi/a8/d2-1994-1999/remont/mechanical-hydraulic/#disc-brakes) . Carry out On Board Diagnostic (OBD). See «ON BOARD DIAGNOSTIC (OBD)»(/audi/a8/d2-1994-1999/remont/warning-system/#on-board-diagnostic-obd-absedlasr) .
6. Connector, ABS wire set Disengage and remove The connector is part of the ABS wire set. Different versions are coded according to component.
7. Brake line Master brake cylinder/secondary piston circuit to hydraulic unit Different versions, see «BRAKE LINE CONNECTIONS AT THE HYDRAULIC UNIT, ABS 5.0»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__brake-line-connections-at-the-hydraulic) and «BRAKE LINE CONNECTIONS AT THE HYDRAULIC UNIT, ABS 5.0»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
8. Master brake cylinder with brake booster
9. Brake line Master brake cylinder/primary piston circuit to hydraulic control unit Different versions, see «BRAKE LINE CONNECTIONS AT THE HYDRAULIC UNIT, ABS 5.0»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__brake-line-connections-at-the-hydraulic) and «BRAKE LINE CONNECTIONS AT THE HYDRAULIC UNIT, ABS 5.0»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
10. Brake line Hydraulic control unit to left rear brake caliper
11. Brake line Hydraulic control unit to right rear brake caliper
12. Brake line Hydraulic control unit to left front brake caliper
13. Screw and washer assembly, 10 Nm
14. Ground (GND) wire Check for proper contact
15. Serrated washer
16. Hex-nut, tighten to 10 Nm.
17. Brake line Hydraulic control unit to right front brake caliper
18. Separation point/brake line to right rear brake caliper Location: Wheel housing - left front longmember, see «BRAKE LINE SEPARATION POINTS»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__brake-line-separation-points)
19. Separation point/brake line to left rear brake caliper Location: Wheel housing - left front longmember, see «BRAKE LINE SEPARATION POINTS»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__brake-line-separation-points)
20. Separation point/brake line to right rear brake caliper Location: Wheel housing - left front longmember, see «BRAKE LINE SEPARATION POINTS»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
21. Separation point/brake line/brake hose Right rear
22. Right rear brake hose
23. Separation point/brake line to left rear brake caliper Location: Wheel housing - left front longmember, see «BRAKE LINE SEPARATION POINTS»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
24. Separation point/brake line/brake hose Left rear
25. Left rear brake hose
26. Separation point/brake line to left front brake caliper Location: Wheel housing - left front longmember. See «BRAKE LINE SEPARATION POINTS»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__brake-line-separation-points) .
27. Toward front of vehicle
28. Separation point/brake line/brake hose Left front
29. Left front brake hose
30. Right front brake hose
31. Separation point/brake line/brake hose Right front
32. Separation point/brake line to Right front brake caliper Location: Wheel housing - front right longmember, see «SEPARATION POINT OF BRAKE LINE, HYDRAULIC UNIT - RIGHT FRONT BRAKE CALIPER»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
33. Hex bolt, 15 Nm
34. Washer
35. Bracket for hydraulic unit Insert hydraulic unit and secure Removing and installing bracket, see «HYDRAULIC UNIT BRACKET, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__hydraulic-unit-bracket-removing-and-installing)

Brake line connections at the hydraulic unit, ABS 5.0

Valid for following vehicles

Front Wheel Drive (FWD) with ABS/EDL

Front Wheel Drive (FWD) with ABS/EDL/ASR

All Wheel Drive (AWD) with ABS/EDL

The following list pertains to (Scheme 4).

1. Hydraulic unit - Master brake cylinder (primary piston circuit)
2. Hydraulic control unit - right rear brake caliper
3. Hydraulic unit - left front brake caliper
4. Hydraulic unit - Master brake cylinder (secondary piston circuit)
5. Hydraulic control unit - left rear brake caliper
6. Hydraulic control unit - right front brake caliper

Note. For vehicles with All Wheel Drive (AWD) and EDL intake control (from 05.95), pressure absorbers are omitted. See BRAKE LINE CONNECTIONS AT THE HYDRAULIC UNIT, ABS 5.0 . EDL intake regulation reduces regulation noise. The functional range of the pressure relief valve in the hydraulic unit is raised from 90 + 25 bar to 170 + 25 bar.

Scheme 2

Note. For vehicles with All Wheel Drive (AWD) and ABS/EDL-pressure regulation (up to 05.95): For vehicles with All Wheel Drive (AWD) and EDL-pressure regulation, two pressure absorbers are screwed into the hydraulic unit (arrows). They moderate pressure spikes in the brake lines and reduce regulation noise. Counterhold on hex-edge of pressure absorber when releasing brake lines.

The following list pertains to (Scheme 5).

1. Hydraulic unit - Master brake cylinder (primary piston circuit)
2. Hydraulic control unit - right rear brake caliper
3. Hydraulic unit - left front brake caliper
4. Hydraulic unit - Master brake cylinder (secondary piston circuit)
5. Hydraulic control unit - left rear brake caliper
6. Hydraulic control unit - right front brake caliper

Note. The functional range of the pressure relief valve in the hydraulic unit is 90 + 25 bar.

Brake line separation points

The following list pertains to (Scheme 6).

1. Hydraulic control unit - right rear brake caliper
2. Hydraulic control unit - left rear brake caliper
3. Hydraulic unit - left front brake caliper

The following list pertains to (Scheme 7).

1. Hydraulic control unit - right rear brake caliper
2. Hydraulic control unit - left rear brake caliper

Scheme 3

Hydraulic unit bracket, removing and installing

The following list pertains to (Scheme 9).

1. Bonded rubber bearing
2. Collar nut, 10 Nm
3. Self-locking nut, 10 Nm Always replace
4. Combination bolt
5. Washer
6. Buffer
7. Bearing bushing
8. Bracket

Removing

See Caution before beginning repairs on electrical system, see ANTI-LOCK BRAKE SYSTEM (ABS) BOSCH 5.0

Scheme 4

Scheme 5

1. Disconnect battery. See «BATTERY DISCONNECT PRECAUTIONS»(/audi/a8/d2-1994-1999/remont/charging-system/#generators-regulators)
2. Pry off lower gap cover, see arrows.
3. Unscrew cover, see arrows.
4. Remove ABS Control Module (w/EDL) -J104- for ABS/EDL or ASR.
5. Disconnect connector from control module.

Installing

Installation is the reverse of removal.

Hydraulic control unit, assembly overview

Brake line tightening torque: 15 Nm.

The following list pertains to (Scheme 14).

1. Hydraulic control unit Brake line connections, see «INSTALLED, UP TO MARCH 1997»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system) and «INSTALLED, AS OF APRIL 1997»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__installed-as-of-april-1997) . Removing and installing, see «ABS HYDRAULIC UNIT, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
2. Collar nut, 12 Nm
3. Suction dampers To be discontinued gradually (will be incorporated in hydraulic control unit) Checking, see «INSTALLED, UP TO MARCH 1997»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__installed-up-to-march-1997)
4. Collar nut, 10 Nm
5. Bonded rubber bearing
6. Bracket
7. Collar nut, 10 Nm
8. Screw and washer assembly, 10 Nm
9. Washer
10. Buffer
11. Bearing bushing

Installed, up to March 1997

Note. Brake fluid may exit when loosening and turning. Protect engine compartment from escaping brake fluid.

F = direction of travel

1. Loosen bolts -1- approx. 1/2 rotation.

Note. When loosening by 1/2 turn, seals maintain contact with the sealing surfaces. This prevents entry of dirt during turning.

Scheme 6

1. Turn suction dampers in direction of arrow until they form a 60° angle to the ABS hydraulic unit.
2. Attach brake lines -A- and -B-.

Note. Counterhold side surfaces of suction dampers when tightening.

1. Tighten bolts -1- to 25 Nm.
2. Bleed brake system, see «BLEEDING BRAKE SYSTEM»(/audi/a8/d2-1994-1999/remont/mechanical-hydraulic/#disc-brakes) .

The following list pertains to (Scheme 16).

1. Master brake cylinder (secondary piston circuit)
2. Master brake cylinder (primary piston circuit)
3. Left rear brake caliper
4. Right rear brake caliper
5. Left front brake caliper
6. Right Front brake caliper

Installed, as of April 1997

1. Master brake cylinder (secondary piston circuit)
2. Master brake cylinder (primary piston circuit)
3. Left rear brake caliper
4. Right rear brake caliper
5. Left front brake caliper
6. Right front brake caliper

Special Tools and Equipment

1. Sealing plugs, repair kit 1 H0 698 311 A
2. Brake pedal depressor e.g. from VAG1813

Scheme 7

1. Disconnect battery. See «BATTERY DISCONNECT PRECAUTIONS»(/audi/a8/d2-1994-1999/remont/charging-system/#generators-regulators).
2. Disengage connector from control module (arrow -1-) and disconnect (arrow -2-). (Scheme 18)
3. Connect bleeder bottle to bleeder screw on front left brake caliper and open bleeder screw.
4. Insert brake pedal depressor between brake pedal and driver's seat. Depress brake pedal at least 60 mm. NOTE: This prevents the brake fluid reservoir from emptying. Do not remove brake pedal depressor until all brake lines have been reconnected to the hydraulic control unit.
5. Close front left bleeder screw. Protect engine compartment from escaping brake fluid.
6. Disconnect brake line connections at hydraulic control unit.
7. Seal brake lines and threaded holes using plugs from repair kit, Part No. 1H0 698 311 A.
8. Remove hex-nuts at hydraulic control unit bracket.
9. Remove hydraulic control unit.

Installation is the reverse of removal.

1. Bleed brake system. See «BLEEDING BRAKE SYSTEM»(/audi/a8/d2-1994-1999/remont/mechanical-hydraulic/#disc-brakes) .
2. Carry out output Diagnostic Test Mode (DTM). See «ON BOARD DIAGNOSTIC (OBD)»(/audi/a8/d2-1994-1999/remont/warning-system/#on-board-diagnostic-obd-absedlasr) .

Electronic Stabilization Program (ESP) Bosch 5.3

Hydraulic unit with hydraulic pump for traction control, assembly overview

Brake line tightening torque: 15 Nm.

The following list pertains to (Scheme 19).

1. Hydraulic control unit Brake line connections, see «BRAKE LINE CONNECTIONS: HYDRAULIC CONTROL UNIT WITH HYDRAULIC PUMP FOR TRACTION CONTROL»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__brake-line-connections-hydraulic-control-unit) Removing and installing, see «ABS HYDRAULIC UNIT, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
2. Collar nut, 12 Nm
3. Collar nut, 10 Nm
4. Bonded rubber bushing, 2 Nm
5. Bracket
6. Collar nut, 10 Nm
7. Screw and washer assembly, 10 Nm
8. Washer
9. Buffer
10. Bearing bushing
11. Hex-nut, tighten to 10 Nm.
12. Bearing bushing
13. Buffer
14. Hydraulic pump for traction control Also called the booster pump Removing and installing, see «ABS HYDRAULIC UNIT, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
15. Bonded rubber bushing, 2 Nm
16. Hex-nut, tighten to 10 Nm
17. Brake fluid reservoir
18. Intake hose Mount at bracket with white paint markings.
19. Intake line Leads to hydraulic pump for traction control
20. Hose clamp
21. Bracket for brake lines Application of brake lines, see «APPLICATION OF BRAKE LINES IN BRACKET»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__application-of-brake-lines-in-bracket)

Application of brake lines in bracket

1. Intake line, hydraulic pump for Anti-slip Regulation (ASR) to brake fluid reservoir
2. From hydraulic pump for Anti-slip Regulation (ASR) to master brake cylinder (primary piston circuit)
3. From ABS hydraulic unit to master brake cylinder (secondary piston circuit)
4. From ABS hydraulic unit to right front brake caliper
5. From ABS hydraulic unit to left front brake caliper

Brake line connections: hydraulic control unit with hydraulic pump for traction control

Brake line tightening torque: 15 Nm.

The following list pertains to (Scheme 21).

1. To left rear brake caliper
2. To right rear brake caliper
3. Hydraulic control module to hydraulic pump for traction control
4. To left front brake caliper
5. To right front brake caliper
6. To master brake cylinder (secondary piston circuit)
7. From hydraulic pump for Anti-slip Regulation (ASR) to master brake cylinder (primary piston circuit)
8. Connecting piece, 12 Nm
9. Hose clamp
10. Intake hose
11. Intake line from hydraulic pump for Anti-slip Regulation (ASR) to brake fluid reservoir

1. Sealing plugs, repair kit 1 H0 698 311 A
2. Brake pedal depressor e.g. from VAG1813

See Caution before beginning repairs on the electrical system. See ELECTRONIC STABILIZATION PROGRAM (ESP) BOSCH 5.3 .

1. Disconnect battery. See «BATTERY DISCONNECT PRECAUTIONS»(/audi/a8/d2-1994-1999/remont/charging-system/#generators-regulators) .

Scheme 8

1. Pull connector housing up enough that connector can be removed.
2. Connect bleeder bottle to bleeder screw on left front brake caliper and open bleeder screw.
3. Insert brake pedal depressor between brake pedal and driver's seat. Depress brake pedal at least 60 mm. NOTE: This prevents the brake fluid reservoir from emptying. Do not remove brake pedal depressor until all brake lines have been reconnected.
4. Close front left bleeder screw. Protect engine compartment from escaping brake fluid.
5. Disconnect brake line connections at hydraulic control unit.
6. Seal brake lines and threaded holes using plugs from repair kit, Part No. 1 H0 698 311 A.
7. Remove hex-nuts at hydraulic control unit bracket.
8. Remove hydraulic control unit.

Installation is the reverse of removal.

1. Bleed brake system. See «BLEEDING BRAKE SYSTEM»(/audi/a8/d2-1994-1999/remont/mechanical-hydraulic/#disc-brakes) .
2. Carry out output Diagnostic Test Mode (DTM). See «ON BOARD DIAGNOSTIC (OBD)»(/audi/a8/d2-1994-1999/remont/warning-system/#on-board-diagnostic-obd-absedlasr) .

Scheme 9

1. VAG1331 torque wrench
2. VAG1410 torque wrench
3. VAG1869/2 brake pedal depressor
4. VAG1551 or VAG1552 Sealing plugs, repair kit: 1 H0 698 311 A Installation location: The hydraulic pump for ESP is located at left in the engine compartment below the hydraulic control module.

See Caution before beginning repairs on the electrical system. See ELECTRONIC STABILIZATION PROGRAM (ESP) BOSCH 5.3 .

Scheme 10

Scheme 11

1. Disconnect battery. See «BATTERY DISCONNECT PRECAUTIONS»(/audi/a8/d2-1994-1999/remont/charging-system/#generators-regulators) . WARNING: Brake lines must not be bent.
2. Raise vehicle.
3. Remove left front wheel.
4. Remove front half of left front wheel housing liner.
5. Unscrew retaining plate for fan resistors.

Note. Protect engine compartment from escaping brake fluid.

Scheme 12

1. Disengage intake hose -1- from hose clamp and remover. see scheme 26
2. Unscrew brake lines -2- and -3-.
3. Seal brake lines and threaded holes using plugs from repair kit, Part No. 1H0 698 311 A.
4. Remove connector and disconnect connector.
5. Open cable ties.
6. Remove hex-nut.
7. Push hydraulic pump out of rear buffers in direction of arrow -A-. see scheme 27
8. Unscrew lower bonded rubber bushing from pump.
9. Remove pump -3- in direction of arrow B.

Installation is the reverse of removal.

1. Bleed brake system. See «BLEEDING BRAKE SYSTEM»(/audi/a8/d2-1994-1999/remont/mechanical-hydraulic/#disc-brakes) .
2. Carry out output Diagnostic Test Mode (DTM). See «ON BOARD DIAGNOSTIC (OBD)»(/audi/a8/d2-1994-1999/remont/warning-system/#on-board-diagnostic-obd-absedlasr) .

ABS/ESP system components, removing and installing

1. Disconnect connector from brake light switch.
2. Remove brake light switch by rotating 90° toward right.

1. Completely remove plunger of brake light switch.
2. Press down brake pedal as far as possible by hand.
3. Guide brake light switch through assembly hole and re-install by rotating 90° toward left.
4. Release brake pedal
5. Connect connector for brake light switch.
6. Press brake pedal. brake lights light up.
7. Remove foot from brake pedal. brake lights must not light up.

Steering angle sensor -G85-, removing and installing

See Caution before beginning repairs on the electrical system. See ABS/ESP SYSTEM COMPONENTS, REMOVING AND INSTALLING .

1. Disconnect battery. See «BATTERY DISCONNECT PRECAUTIONS»(/audi/a8/d2-1994-1999/remont/charging-system/#generators-regulators) .
2. Remove driver-side airbag unit. See appropriate Air Bag Restraint Systems article.
3. Remove airbag unit and steering wheel. See appropriate Air Bag Restraint Systems article.
4. Put wheels in straight-ahead position.

Scheme 13

Scheme 14

1. Remove bolts (arrows) and trim -1-.
2. Remove lower gap cover in direction of arrow.
3. Remove bolts -1- and grip -2- for steering column adjustment. see scheme 30
4. Remove screws -7- and -8- and remove lower trim for steering column switch -4-.
5. Disconnect harness connector for switch -6- and unscrew switch. see scheme 30

Note. Illustration shows trim for steering column switch, up to 06.97.

Scheme 15

Steering Angle Sensor -G85- is installed in housing -1- together with spiral spring.

Scheme 16

Scheme 17

1. Disconnect connectors -1- and -2-.
2. Carefully lift hooks (arrows) and remove steering angle sensor.

Steering angle sensor -G85- must be in center position before installation.

Scheme 18

1. Position steering angle sensor until tabs engage.
2. Remove transport protection.
3. A yellow dot must be visible in the hole (arrow -1-). see scheme 34
4. Markings (arrows) must also be flush.

Be sure that center position is maintained

Rest of installation is the reverse of removal.

1. Carry out Zero position compensation of Steering Angle Sensor -G85-. See «BASIC SETTING (SCAN TOOL FUNCTION 04)»(/audi/a8/d2-1994-1999/remont/warning-system/#on-board-diagnostic-obd-absedlasr__basic-setting-scan-tool-function-04) .

See Caution before beginning repairs on the electrical system. See ABS/ESP SYSTEM COMPONENTS, REMOVING AND INSTALLING .

1. Disconnect battery. See «BATTERY DISCONNECT PRECAUTIONS»(/audi/a8/d2-1994-1999/remont/charging-system/#generators-regulators) .

1. Switch off ignition.
2. Remove driver seat. See «FRONT SEATS»(/audi/a8/d2-1994-1999/remont/seats/#seats-frames) .

The Sensor for transverse acceleration -G202- is installed under the driver's seat.

Bolt tightening torque: 5 Nm

Scheme 19

Sensor for transverse acceleration -G200

is installed under the drivers' seat.

Be careful!

The sensor for transverse acceleration is sensitive to strong vibrations.

If the sensor drops on the Ground, full function of the sensor is no longer guaranteed. If this is the case, you cannot reuse the sensor.

Bolt tightening torque: 2 Nm

Rest of installation is the reverse of removal.

Scheme 20

1. Install driver seat. See «FRONT SEATS»(/audi/a8/d2-1994-1999/remont/seats/#seats-frames) .

ABS/ESP system components at front axle, removing and installing

The following list pertains to see scheme 37.

1. Drive axle with ABS wheel speed sensor rotor Check rotor for dirt and damage. See «ABS WHEEL SPEED SENSOR ROTOR, CHECKING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__abs-wheel-speed-sensor-rotor-checking) . If rotor is damaged, outer constant velocity joint must be replaced. See «SUSPENSION - FRONT»(/audi/a8/d2-1994-1999/remont/suspension-front/#suspension-front) . Outer constant velocity joint is supplied with ABS wheel speed sensor rotor as replacement part.
2. Screw and washer assembly, 10 Nm
3. Bracket Insert ABS wheel speed sensor wire in bracket with rubber grommet.
4. Collar screw
5. Double clamp Always replace. Before installing, coat hole in wheel bearing housing with brake cylinder paste G 000 650. Push into wheel bearing housing up to stop.
6. Sealing cuff
7. ABS wheel speed sensor Always replace, see «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)

Scheme 21

1. Switch off ignition.
2. Raise vehicle.
3. Remove wheel.
4. Remove front half of wheelhousing liner.
5. Disconnect harness connector for wheel speed sensor wire.
6. Disconnect ABS wheel speed sensor wiring from retainers.
7. Pull ABS wheel speed sensor out of wheel bearing housing.

1. Replace clamping sleeve (see «ABS/ESP SYSTEM COMPONENTS AT FRONT AXLE, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__absesp-system-components-at-front-axle) , item -5-).
2. Before inserting ABS wheel speed sensor, install sealing cuff and coat wheel speed sensor completely using G 000 650 solid lubricant.
3. Press ABS wheel speed sensor in by hand until impact.
4. Connect ABS wheel speed sensor wiring and snap grommets into retainers.
5. Mount wheels and tighten to 120 Nm.

Scheme 22

1. Raise vehicle.
2. Remove wheel.
3. Pull ABS wheel speed sensor out of wheel bearing housing.
4. Check rotor for dirt and damage (arrow).

Note. If ABS wheel speed sensor rotor is damaged or dirty, remove drive axle. If damaged, replace outer constant velocity joint together with ABS wheel speed sensor rotor.

Scheme 23

1. To clean rotor, release collar bolt at drive axle and slide drive axle inward.

Note. Always use a new collar bolt!

1. Tighten collar bolt to 190 Nm and turn an additional 180°.

ABS/ESP system components at rear axle, removing and installing

The following list pertains to see scheme 41.

1. Stab axle with rotor (Front Wheel Drive) Check rotor for dirt and damage. See «ABS WHEEL SPEED SENSOR ROTOR, CHECKING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system) . Stab axle is supplied together with rotor as replacement part.
2. Drive axle with ABS wheel speed sensor rotor (all-wheel drive) Check rotor for dirt and damage. See «ABS WHEEL SPEED SENSOR ROTOR, CHECKING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system) . If rotor is damaged, outer constant velocity joint must be replaced together with ABS wheel speed sensor rotor. See «SUSPENSION - REAR»(/audi/a8/d2-1994-1999/remont/suspension-rear/#suspension-rear) . Outer constant velocity joint is supplied with ABS wheel speed sensor rotor as replacement part.
3. ABS wheel speed sensor Removing and installing, see «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system)
4. Sealing cuff
5. Double clamp Always replace Before installing, coat hole in wheel bearing housing with brake cylinder paste G 000 650. Push into wheel bearing housing up to stop
6. Collar screw
7. Clip

1. Disengage and disconnect harness connector for wheel speed sensor wire. Unclip ABS wheel speed sensor wire.

1. Switch off ignition.
2. Raise vehicle.
3. Remove wheel.
4. Disconnect harness connector for wheel speed sensor wire.
5. Disconnect ABS wheel speed sensor wiring from retainers.
6. Pull ABS wheel speed sensor out of wheel bearing housing.

1. Replace clamping sleeve. See «ABS/ESP SYSTEM COMPONENTS AT REAR AXLE, REMOVING AND INSTALLING»(/audi/a8/d2-1994-1999/remont/anti-locktraction-control/#antilock-brake-system__absesp-system-components-at-rear-axle) , item -5-.
2. Before inserting ABS wheel speed sensor, install sealing cuff and coat wheel speed sensor completely using G 000 650 solid lubricant.
3. Press ABS wheel speed sensor in by hand until impact.
4. Connect ABS wheel speed sensor wiring and snap in retainers.
5. Mount wheels and tighten to 120 Nm.

ABS wheel speed sensor rotor, checking

1. Raise vehicle.
2. Remove wheel.
3. Pull ABS wheel speed sensor out of wheel bearing housing.
4. Check rotor for dirt and damage.

Note. If ABS wheel speed sensor rotor is damaged or dirty, remove stab axle or drive axle. If damaged, replace outer constant velocity joint together with ABS wheel speed sensor rotor.

See also:
• ON BOARD DIAGNOSTIC (OBD)
• BLEEDING BRAKE SYSTEM
• AXLE SHAFTS
• SUSPENSION - FRONT
• STEERING
• SUSPENSION - REAR
• EXAMPLE: SWITCH OFF EMERGENCY (BACK-UP) BATTERY
• EXAMPLE: SWITCH ON EMERGENCY (BACK-UP) BATTERY
• BATTERY DISCONNECT PRECAUTIONS
• BASIC SETTING (SCAN TOOL FUNCTION 04)
• FRONT SEATS
• ABS WHEEL SPEED SENSOR ROTOR, CHECKING
• ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING
• STEERING ANGLE SENSOR -G85-, REMOVING AND INSTALLING
• BRAKE LINE CONNECTIONS AT THE HYDRAULIC UNIT, ABS 5.0
• BRAKE LINE SEPARATION POINTS
• HYDRAULIC UNIT BRACKET, REMOVING AND INSTALLING
• INSTALLED, AS OF APRIL 1997
• INSTALLED, UP TO MARCH 1997
• BRAKE LINE CONNECTIONS: HYDRAULIC CONTROL UNIT WITH HYDRAULIC PUMP FOR TRACTION CONTROL
• APPLICATION OF BRAKE LINES IN BRACKET
• ELECTRONIC STABILIZATION PROGRAM (ESP) BOSCH 5.3
• ABS/ESP SYSTEM COMPONENTS, REMOVING AND INSTALLING
• ABS/ESP SYSTEM COMPONENTS AT FRONT AXLE, REMOVING AND INSTALLING
• ABS/ESP SYSTEM COMPONENTS AT REAR AXLE, REMOVING AND INSTALLING