audi Workshop Repair Guides

Audi Workshop Manuals

General information
General information
The anti-lock brake system is basically maintenance-free.
Testing, removing, installing and repair work may only be performed by qualified personnel.
Failure to observe the information described in this Workshop Manual may result in damage to the system and could make the vehicle unsafe.
The vehicle is equipped with a diagonally split ABS brake system. The servo-assistance is pneumatic, supplied by the vacuum brake servo unit.
Vehicles equipped with the ABS Mark 60 do not have a mechanical brake pressure regulator. A specially matched software in the control unit controls the rear axle brake pressure regulation.
Malfunctions in the ABS system do not influence the brake system and servo action. The conventional braking system remains functional even without ABS. However, the vehicle's braking behaviour can change. After the ABS warning lamp comes on, the rear wheels can lock early when braking!
t  Before carrying out repair work on the anti-lock brake system, determine the cause of the problem using self-diagnosis.
t  Always switch off ignition before unplugging the connector at hydraulic control unit.
t  If a new hydraulic control unit has been fitted, it must be encoded. Vehicle diagnostic, testing and information system -VAS 5051 x- or -VAS 5052-.
t  Bleed brake system after performing work involving opening of brake system: ABS/ESP Mark 60/ ABS Mark 70 → Chapter. To do so, use for example the brake filling and bleeding equipment -V.A.G 1869- or brake filling and bleeding equipment -VAS 5234-.
t  Observe the relevant safety precautions and information when handling brake fluid.
t  Absolute cleanliness is required when working on the anti-lock brake system; avoid any products that contain mineral oil, such as oil, grease, etc.
t  Ensure that no brake fluid enters electrical connectors.
t  Thoroughly clean all connections and the adjacent areas before loosening, but do not use aggressive cleaning agents such as brake cleaner, petrol, thinners or similar.
t  Place removed parts on a clean surface and cover them up.
t  Carefully cover or seal open components if repairs are not to be carried out immediately. Use plugs from repair kit; Part No. → ETKA.
t  When the system is open do not work with compressed air and do not move the vehicle.
t  Do not use fluffy cloths.
t  Only use genuine spare parts from original packaging.
t  Only remove replacement parts from packaging immediately prior to installation.
t  During the final road test, ensure that at least one ABS-controlled braking operation is performed (pulsations must be felt at the brake pedal).
t  During painting operations, the electronic control unit can be exposed to a maximum temperature of 95 °C for only a short period, and to a maximum of 85 °C for longer periods (approx. 2 hours).
t  Before carrying out welding work with an electric welding unit, refer to → General notes; Body repairs; Safety notes.

Brake system > ABS, ADR, TCS, EDL, ESP > General information