Procedures

ABS System, Servicing

CAUTION!
The anti-lock brake system is generally maintenance-free.

Testing, assembly, and repair work may only be performed by qualified personnel.

By not observing the points described in the repair information, the system can be damaged and vehicle safety could be compromised.

• Before performing repair work on the anti-lock brake system, determine the cause of the malfunction using On-Board Diagnostics (OBD).

• When installing a new hydraulic control unit, check the coding using the=> Vehicle Diagnosis, Testing And Information System (Vas 5051B) or (VAS 5052)

• Switch ignition off before installation work. If the radio in the vehicle is coded, find out the radio code before disconnecting the battery ground cable.

• When working with brake fluid, observe relevant safety precautions and notes. Refer to => [ Brake Fluid ] Description and Operation.

• If any work requires opening the hydraulic system, the first bleed the brake system using Bleeding with Brake Filler/Bleeder Unit (V.A.G 1869) or V.A.S 5234=> Repair Group, refer to => [ Bleeding, with Electronic Stability Program ] Service and Repair. Perform a high and low pressure test on the brake system, refer to => [ High and Low Pressure Testing ] High and Low Pressure Testing

• During the final road test, perform an ABS-controlled braking at least one time (pulsing must be felt in the brake pedal). See => Vehicle Diagnosis, Testing and Information System (VAS 5051B) or (VAS 5051B).

• 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.

• 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.

• Place parts that have been removed on a clean surface and cover.

• Carefully cover over opened components or seal, if repairs are not carried out immediately. (Sealing plugs, use repair kit 1 H0 698 311 A)

• Only use lint-free cloths.

• Only unpack replacement parts immediately prior to installation.

• Only use parts in their original packaging.

• Do not work with compressed air and do not move vehicle while the system is open.

• Make sure that brake fluid does not enter harness connectors.