Antilock Brakes / Traction Control Systems: Service Precautions

ABS


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 manual, 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).

• If a new ABS hydraulic unit, check the coding using the vehicle diagnosis, testing and information system (VAS 5051 B) or (VAS 5052).

• Switch ignition off before installation work. On vehicles with coded radio unit, determine code and disconnect battery Ground (GND) cable.

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

• Bleed brake system with the brake filler/bleeder unit (VAS 5234) for all work that requires opening the hydraulic system. High and low pressure testing should also be performed 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 5051 B) or (VAS 5052).

• Absolute cleanliness is required when working on the anti-lock brake system, it is not permitted to 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 genuine 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.