Home ReviewsRefund
Home/Audi/A6/Audi A6 C5 facelift (2001-2004)/Repair manual/Anti-Lock/traction Control/Brake System - ABS: Overview
Contents Wiring diagrams Section: Anti-Lock/traction Control All sections

Brake System - ABS: Overview Audi A6 C5 facelift

Anti-Lock/traction Control 4 illustrations ~1264 words

General information on the anti-lock brake system

CAUTIONBefore beginning repairs on the electrical system: Obtain the anti-theft radio security code. Switch the ignition off. Disconnect the battery Ground (GND) strap. On vehicles equipped with Audi Telematics by OnStar®, switch-off the emergency (back-up) battery for the Telematic/Telephone Control Module prior to disconnecting vehicle battery. See EMERGENCY BATTERY, SWITCHING OFF/ON . After reconnecting vehicle battery, re-code and check operation of anti-theft radio. Also check operation of clock and power windows according to Repair Manual and/or Owner's Manual. After reconnecting vehicle battery on vehicles equipped with Audi Telematics by OnStar®, switch-on the emergency (back-up) battery for the Telematic/Telephone Control Module. See EMERGENCY BATTERY, SWITCHING OFF/ON .

ABS system, general information

The new Audi A6 is equipped with the Bosch 5.3 ABS/EDL system as standard equipment.

A traction control system (ASR) may also be installed as optional equipment on vehicles with front wheel drive.

The ABS hydraulic system is divided diagonally (two circuits). The vacuum brake servo unit boosts the brakes pneumatically.

Hydraulic unit -a- and control module - b- are combined as a single unit. This is referred to as the hydraulic control unit.

The direct connection between these components reduces possible sources of malfunctions. The hydraulic control unit is not serviceable and must be replaced if malfunctioning.

Do not remove bolts connecting individual components of the hydraulic control unit.

Scheme 431

Scheme 431: ABS system, general information
Scheme 431: ABS system, general information

ABS/ESP Bosch 5.3 assembly overview

Note. The following list refers to items in (Scheme 432).

  1. Electronic stabilization program hydraulic pump for traction control -V156- only with ESP Removing and installing, see «HYDRAULIC PUMP FOR ELECTRONIC STABILIZATION PROGRAM (ESP), REMOVING AND INSTALLING»(ref-196273-S33769173612005100800000)
  2. Sender 1 for brake booster -G201- in ESP pump (only with ESP)
  3. ABS return flow pump relay -J105- for Bosch 5.3
  4. ABS solenoid valve relay -J106- for Bosch 5.3
  5. ABS hydraulic unit -N55- with ABS control module (w/EDL) -J104- The ABS hydraulic pump -V64-, the ABS hydraulic unit -N55- and the ABS Control Module (w/EDL) -J104- (for Bosch 5.3 only) form the hydraulic control unit.
  6. Brake fluid level warning switch -F34
  7. Rotor for right front speed sensor Checking, see «ROTOR, CHECKING»(ref-196273-S32250046642005100800000)
  8. Right front ABS wheel speed sensor -G45- Removing and installing, see «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S37558528102005100800000)
  9. ABS control module (w/EDL) -J104- (with ESP) Installation location: passenger footwell
  10. Anti-Slip control switch - E132- Installation location: on the center console
  11. Steering angle sensor - G85- (for vehicles with) ESP Installation location: Installed on the steering column Removing and installing, see «STEERING ANGLE SENSOR -G85-, REMOVING AND INSTALLING»(ref-196273-S09082487532005100800000)
  12. Parking brake warning light switch -F9- Installation location: on the parking brake lever assembly
  13. Rotor for right rear speed sensor Checking: See «ROTOR, CHECKING»(ref-196273-S00357041182005100800000) (FWD), or «ROTOR, CHECKING»(ref-196273-S41378148972005100800000) (AWD).
  14. Right rear ABS wheel speed sensor -G44- Removing and installing: See «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S01231555872005100800000) (FWD), or «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S06105173862005100800000) (AWD).
  15. Left rear ABS wheel speed sensor -G46- Removing and installing: See «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S01231555872005100800000) (FWD), or «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S06105173862005100800000) (AWD).
  16. Rotor for left-rear speed sensor Checking: See «ROTOR, CHECKING»(ref-196273-S00357041182005100800000) (FWD), or «ROTOR, CHECKING»(ref-196273-S41378148972005100800000) (AWD).
  17. Sensor for transverse acceleration -G200- New design in a housing together with -G202- 2.1 ltr quattro vehicles, MY 98 removing and installing, see «SENSOR FOR TRANSVERSE ACCELERATION -G200- AND SENDER FOR ROTATION RATE -G202- FOR BOSCH 5.3 SYSTEM IN 2.1 LTR. QUATTRO, MY 98, REMOVING AND INSTALLING»(ref-196273-S00991609632005100800000) Removing and installing, see «SENSOR FOR TRANSVERSE ACCELERATION -G200- AND SENDER FOR ROTATION RATE -G202- FOR BOSCH 5.3, REMOVING AND INSTALLING»(ref-196273-S03958439322005100800000)
  18. Sender for rotation rate - G202- 2.1 ltr quattro vehicles, MY 98 removing and installing, see «SENSOR FOR TRANSVERSE ACCELERATION -G200- AND SENDER FOR ROTATION RATE -G202- FOR BOSCH 5.3 SYSTEM IN 2.1 LTR. QUATTRO, MY 98, REMOVING AND INSTALLING»(ref-196273-S00991609632005100800000) Removing and installing, see «SENSOR FOR TRANSVERSE ACCELERATION -G200- AND SENDER FOR ROTATION RATE -G202- FOR BOSCH 5.3, REMOVING AND INSTALLING»(ref-196273-S03958439322005100800000)
  19. ABS return flow pump relay -J105- for Bosch 5.3 only Installation location: on fuse box
  20. ABS solenoid valve relay -J106- for Bosch 5.3
  21. Warning light for brake system -K118- Installation location: in the instrument cluster in the driver information system
  22. ABS warning light -K47- Installation location: in instrument cluster
  23. Parking brake indicator light -K14- Installation location: in instrument cluster
  24. Traction control indicator light -K86- Installation location: in instrument cluster
  25. Brake light switch -F- Removing and installing the brake light switch: See «ABS/ESP SYSTEM COMPONENTS, REMOVING AND INSTALLING»(ref-196273-S10120109142005100800000) .
  26. Rotor for left front speed sensor Checking, see «ROTOR, CHECKING»(ref-196273-S32250046642005100800000) .
  27. Left front ABS wheel speed sensor -G47- Removing and installing, see «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S37558528102005100800000)

Scheme 432

Scheme 432
Scheme 432

ABS hydraulic control unit, assembly overview

Tightening torque for all brake lines on the Audi A6 is 15 Nm.

Note. The following list refers to items in (Scheme 433).

  1. Brake master cylinder and brake servo
  2. Brake line Brake master cylinder/primary piston circuit to hydraulic unit
  3. Brake line Brake master cylinder/secondary piston circuit to hydraulic unit
  4. Brake line Hydraulic unit to left-front brake caliper
  5. Brake line Hydraulic unit to right-front brake caliper
  6. Suction dampers Design to improve pressure build-up during operation of EDL To be discontinued gradually (will be incorporated in the hydraulic control unit)
  7. Brake line Hydraulic control unit to left-rear brake caliper
  8. Brake line Hydraulic control unit to right-rear brake caliper
  9. Hex nut, 10 Nm
  10. Hex bolt, 10 Nm
  11. Bracket

Scheme 433

Scheme 433
Scheme 433

ABS/ESP Bosch 5.7, assembly overview

Note. The following list refers to items in see scheme 34.

  1. Bracket for hydraulic control unit Removing and installing, see «HYDRAULIC CONTROL UNIT, REMOVING AND INSTALLING»(ref-196273-S42345126952005100800000)
  2. Vacuum pump for brake servo Only on gasonline engines in conjunction with an automatic transmission
  3. ABS control module (w/EDL) - J104- The ABS hydraulic unit -N55- and the ABS control module (w/EDL) -J104- are J104- are combined to form the hydraulic control unit. Removing and installing, see «HYDRAULIC CONTROL UNIT, REMOVING AND INSTALLING»(ref-196273-S42345126952005100800000)
  4. ABS hydraulic unit -N55- with ABS control module (w/EDL) -J104- The ABS hydraulic unit -N55- and the ABS control module (w/EDL) -J104- are combined to form the hydraulic control unit. Removing and installing, see «HYDRAULIC CONTROL UNIT, REMOVING AND INSTALLING»(ref-196273-S42345126952005100800000)
  5. Sender 1 for brake booster -G201- Bolted onto hydraulic control unit Tightening torque 20 Nm
  6. ABS hydraulic unit -N55- with ABS control module (w/EDL) -J104
  7. Rotor for right-front speed sensor Checking, see «ROTOR, CHECKING»(ref-196273-S32250046642005100800000)
  8. Right front ABS wheel speed sensor -G45- Removing and installing, see «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S37558528102005100800000)
  9. Brake fluid level warning switch -F34
  10. Instrument cluster
  11. Anti-slip control switch - E132- Installation location: on the center console
  12. Steering angle sensor - G85- for ESP Installation location: in the coil connector with slip ring on steering column Performing zero position compensation => VAS 5051 vehicle diagnostic, testing and information system
  13. Parking brake warning light switch -F9- Installation location: on the parking brake lever assembly
  14. Rotor for right-rear speed sensor Checking: See «ROTOR, CHECKING»(ref-196273-S00357041182005100800000) (FWD), or «ROTOR, CHECKING»(ref-196273-S41378148972005100800000) (AWD).
  15. Right rear ABS wheel speed sensor -G44- Removing and installing: See «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S01231555872005100800000) (FWD vehicles), or «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S06105173862005100800000) (AWD vehicles).
  16. Sensor for transverse acceleration -G200- and sender for rotation rate - G202- Installation location: underneath the radio Removing and installing, see «SENSOR FOR TRANSVERSE ACCELERATION -G200- AND SENDER FOR ROTATION RATE -G202- FOR BOSCH 5.7, REMOVING AND INSTALLING»(ref-196273-S35317053622005100800000)
  17. Left rear ABS wheel speed sensor -G46- Removing and installing: See «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S01231555872005100800000) (FWD), or «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S06105173862005100800000) (AWD).
  18. Rotor for rear left speed sensor Checking: See «ROTOR, CHECKING»(ref-196273-S00357041182005100800000) (FWD), or «ROTOR, CHECKING»(ref-196273-S41378148972005100800000) (AWD).
  19. Traction control indicator light -K86- Installation location: in instrument cluster For further information refer to the owner's manual.
  20. ABS warning light -K47- Installation location: in instrument cluster For further information refer to the owner's manual.
  21. Warning light for brake system -K118- Installation location: in instrument cluster in driver information system For further information refer to owner's manual.
  22. Brake light switch -F- Removing and installing brake light switch, see «ABS/ESP SYSTEM COMPONENTS, REMOVING AND INSTALLING»(ref-196273-S10120109142005100800000) Adjusting, see «ABS/ESP SYSTEM COMPONENTS, REMOVING AND INSTALLING»(ref-196273-S10120109142005100800000)
  23. Rotor for front left speed sensor Checking, «ROTOR, CHECKING»(ref-196273-S32250046642005100800000)
  24. Left front ABS wheel speed sensor -G47- Removing and installing, see «ABS WHEEL SPEED SENSOR, REMOVING AND INSTALLING»(ref-196273-S37558528102005100800000)

Scheme 434

Scheme 434
Scheme 434

More articles — Brake System - ABS