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Home >> Audi >> 2013 >> A4 Base >> Repair and Diagnosis (Single Page) >> Brakes >> Traction Control >> Antilock Brake System (Sedan) (As Of 09.2011) >> 45 Antilock Brake System >> Description And Operation >> Abs/Electronic Stabilization Program, BOSCH 8.1, Component Overview

Abs/Electronic Stabilization Program, BOSCH 8.1, Component Overview

The Bosch ESP 8.1 has the following functions:

The brake system is distributed diagonally. The vacuum brake servo unit boosts the brakes pneumatically.

NOTE:

ABS malfunctions do not affect the brake system and the booster. Conventional brake system stays operative even without ABS. A change in braking behavior should be checked. When the ABS warning lamp comes on the rear wheels can lock-up early when braking!

Malfunction sources are reduced by direct connection of components named. The components are replaced instead of repaired.

Fig 1: Abs/Electronic Stabilization Program, Bosch 8.1 Component Overview
GWWA45-10105Courtesy of AUDI OF AMERICA, LLC
  1. 1 -

    Right Rear ABS Wheel Speed Sensor -G44-

  2. 2 -

    Left Rear ABS Wheel Speed Sensor -G46-

  3. 3 -

    ESP Sensor Unit -G419-

    • 9 Nm
    • Component location: under the left seat.
    • Removing and installing, refer to ESP Sensor Unit -G419- / ESP Sensor Unit 2 -G536- .
    • Combined transverse acceleration sensor -G200-, rotation rate sensor -G202-, and longitudinal acceleration sensor -G251-.
    • Can be tested in "Guided fault finding  " with the vehicle diagnostic tester.
    • Observe installation instructions.
    • Check the arrow in the direction of travel when installing.
  4. 4 -

    Brake Lamp Sensor

    • Component location: on brake pedal.
    • Removing and installing, refer to BRAKE LAMP SENSOR .
    • Can be tested in "Guided fault finding  " with the vehicle diagnostic tester.
      NOTE:

      Cannot be reused after removal.

  5. 5 -

    Brake Pedal

  6. 6 -

    Electromechanical Parking Brake Indicator Lamp -K213-

    • Located in the tachometer.
    • Lights up when the parking brake is engaged and the ignition is switched on.
    • Lights up for 20 seconds when the parking brake is engaged and the ignition is switched off.
    • Blinks after engaging the parking brake if the brake pressure is not sufficient to prevent the vehicle from rolling.
  7. 7 -

    Brake System Indicator Lamp -K118-

    • Located in the tachometer.
    • Turns on with the ABS indicator lamp when the ABS system malfunctions.
    • Blinks when the brake fluid is too low.
    • Blinks when there is a malfunction in the brake system.
      NOTE:

      The malfunction is indicated more precisely when the "SET button" in the instrument cluster is pressed.

  8. 8 -

    ABS Indicator Lamp -K47-

    NOTE:

    The indicator lamp monitors the ABS and the Electronic Differential Lock (EDL).

    • Component location: in the tachometer.
    • Lights up for several seconds when ignition is switched on and goes out after an automatic ABS system self-check if there are no malfunctions in the ABS system.
    • There is an ABS malfunction if the indicator light:
      • Does not light up when ignition is switched on.
      • Does not go out after a few seconds.
      • Lights up while driving.
    • ABS malfunctions have no effect on the brake system. However, a change in braking behavior should be checked.
      NOTE:

      The Electronic Differential Lock (EDL) and ABS work together. The ABS indicator light lights up when the EDL malfunctions.

  9. 9 -

    ASR/ESP Indicator Lamp -K155-

    • Component location: in the tachometer.
    • Blinks when driving if ESP/ASR engages regularly.
    • Comes on when ignition is switched on and goes out after a short self-check.
    • Comes on if there is an ESP system malfunction.
    • Comes on if there is an ABS system malfunction because ESP and ABS work together.
    • Comes on when the ASR is switched off.
    • Lights up during sensor programming if:
      • The battery was disconnected and connected.
      • Vehicle was started with jump start.
      • The battery is too weak.
    • After the sensor programming procedure, the ESP light goes out after driving a short distance.
  10. 10 -

    Left Front ABS Wheel Speed Sensor -G47-

    • Removing and Installing, refer to FRONT ABS WHEEL SPEED SENSORS .
    • Can be tested in "Guided fault finding  " with the vehicle diagnostic tester.
  11. 11 -

    ABS Hydraulic Unit -N55- / ABS Control Module -J104-

  12. 12 -

    Return Ring

  13. 13 -

    Steering Angle Sensor -G85-

    • Component location: Installed in coil ring with slip ring on steering column, refer to => 69.
    • Removing and Installing, refer to Steering Angle Sensor -G85- .
    • Perform zero adjustment.
  14. 14 -

    Right Front ABS Wheel Speed Sensor -G45-

  15. 15 -

    ASR/ESP Button -E256-

    • Component location: Inside center console.
    • Switches the ASR off and on.
  16. 16 -

    Audi Hold Assist Pressure Switch

  17. 17 -

    Parking Brake Pressure Switch -F234-

  18. 18 -

    Diagnostic Connection

    • Component location: cover in driver footwell.
Fig 2: Connecting Diagnostic Cable VAS 5051/5A To Diagnostic Connector
GWWA00-10303Courtesy of AUDI OF AMERICA, LLC
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