Antilock Brakes / Traction Control Systems: Service Precautions

ABS repair work notes

WARNING:
The anti-lock brake system is basically maintenance free.
Testing, removing, installing and repair work must only be performed by qualified personnel.
Failure to observe the points described in this repair information may result in damage to the system and could make the vehicle unsafe.

^ Before carrying out repair work on the anti-lock brake system, determine the cause of the problem with the aid of the self-diagnosis
^ When installing a new hydraulic control module, always check its coding.
(Guided Fault Finding in VAS 5051)
^ Switch off the ignition before removing and installing components. If the vehicle is equipped with a coded radio, obtain the security code before disconnecting the ground strap of the battery.
^ Observe the relevant safety precautions and information when handling brake fluid.
^ If hydraulic system has to be opened, bleed the braking system after the work is finished (use VAS 5234), Refer to Brake Bleeding, Service and Repair. In addition, a high and low-pressure test should be carried out on the brake system, Refer To Hydraulic System, Testing and Inspection.
^ During the concluding road test, ensure that an ABS-controlled brake application is carried out at least once (can be felt from the pulsing of the brake pedal).
(Guided Fault Finding in VAS 5051)
^ Absolute cleanliness is required when working on the anti lock brake system, and it is not permitted to use any products which contain mineral oil, such as oil, grease etc.
^ Thoroughly clean all unions and the adjacent areas before undoing them, but do not use aggressive cleaning agents such as brake cleaner, gasoline, thinners or similar.
^ Place removed parts on a clean surface and cover.
^ Carefully cover or seal open components if repairs cannot be carried out immediately. (Use plugs, repair set Ho 698 311 A)
^ Only use lint-free cloths.
^ Do not remove replacement parts from their wrapping until you are ready to install them.
^ Only use genuine parts in their original packaging.
^ When the system is open do not work with compressed air and do not move the vehicle.
^ Ensure that no brake fluid enters plug connectors.