Antilock Brakes / Traction Control Systems: Service Precautions

Notes for repair work on ABS

CAUTION: The anti-locking brake system is basically maintenance-free.
Tests, installation and repair work must always be carried out by properly trained technicians.
Ignoring points made may result in damage to the system and could make the vehicle unsafe.

CAUTION: Before beginning repairs on the electrical system:
^ Obtain the anti-theft radio security code.
^ Switch the ignition off.
^ Disconnect the battery Ground (GND) strap.
^ On vehicles equipped with Audi Telematics by OnStar, switch-off the emergency (back-up) battery for the Telematic/Telephone Control Module prior to disconnecting vehicle battery.
^ After reconnecting vehicle battery, re-code and check operation of anti-theft radio. Also check operation of clock and power windows.
^ After reconnecting vehicle battery on vehicles equipped with Audi Telematics by OnStar, switch-on the emergency (back-up) battery for the Telematic/Telephone Control Module.

Note:
^ Before carrying out repair work on the anti-locking system, determine the cause of the malfunction using On Board Diagnostic (OBD).
^ When installing a new hydraulic control unit, always check the coding
^ Always switch off the ignition before carrying out installation or repair work. On vehicles with a coded radio, find out the anti-theft code and disconnect the battery Ground (GND) strap.
^ When working with brake fluid, observe the relevant safety precautions and notes.
^ Bleed brake system after work which involves opening the hydraulic system using VAS 5234. Additionally, perform high-pressure and low-pressure tests.
^ During the final road test, make sure that at least one ABS-controlled braking operation is performed (pulsations must be felt at the brake pedal).
^ Absolute cleanliness is required when working on the anti-locking 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 open components or seal, if repairs cannot be carried out immediately. (Use sealing plugs from repair kit 1 H0 698 311 A).
^ Do not use fluffy cloths.
^ Remove replacement parts from packaging immediately prior to installation.
^ Only use genuine packed parts.
^ When the system is open do not work with compressed air and do not move the vehicle.
^ Make sure that no brake fluid enters plug connectors.