General Repair Notes

The anti-lock brake system (ABS) is basically maintenance-free, however, note the points when working on vehicles with ABS:
^ Before beginning repair work on the ABS system, determine the cause of the malfunction using On Board Diagnostic.
^ Before beginning any welding work with an electric welding unit, disconnect the ABS Control Module connector
^ Before working on the ABS system, disconnect the Battery Ground strap. Obtain the radio code on vehicles with a coded radio.
^ After work on the ABS system, reconnect and tighten Battery Ground strap.
^ When working with brake fluid, observe the valid, relevant safety precautions and notes.
^ Remove as much brake fluid as possible from the reservoir with an extraction bottle before beginning work that necessitates opening the hydraulic system.
^ Seal brake lines/hoses and connections with suitable plugs (repair kit, Part No. 1 HO 698 311) when performing work which necessitates opening the hydraulic system.
^ After work which necessitates opening the brake hydraulic system, bleed the brake system with brake filling and bleeding tool US 1116 or equivalent.
^ Do not drive vehicle with the ABS Control Module disconnected.
^ It is sufficient to perform a simple functional check after any work on the brake system which did not directly affect parts of the ABS system. The Malfunction Indicator Lamp (MIL) in the instrument cluster must not come on when a speed of 6 km/h (4 mph) is exceeded if the ABS system. is functioning correctly.
^ If work is performed on the hydraulic unit, the ABS Control Module, the Wheel Speed Sensors, wiring harness or if components are replaced, e.g. brake lines/hoses, brake pressure regulator, in the course of accident repairs, the entire ABS system must be tested with ABS tester VAG 1710.
^ During the final road test, ensure that a controlled brake test is performed at least once (pulsations must be felt at the brake pedal).
^ Absolute cleanliness is required when working on the ABS brake system. Do not use any products which contain mineral oils, greases etc.
^ Thoroughly clean all connections and the adjacent areas before loosening. Do not use aggressive cleaning agents such as brake cleaner, thinners, etc.
^ Place removed parts on a clean surface and cover.
^ Do not use fluffy cloths.
^ Carefully cover or seal open components if repairs cannot be carried out immediately.
^ Only remove replacement parts from packaging immediately prior to installation.
^ Only use genuine packaged parts.
^ When the system is open do not use compressed air in the immediate area and do not move the vehicle.
^ Ensure that no brake fluid enters wiring connectors.