General Information on the Anti-Lock Brake System

General information on the anti-lock brake system

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 A, switch-off the emergency (backup) 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 according to Owner's Manual.
^ After reconnecting vehicle battery on vehicles equipped with Audi Telematics by OnStar, switch-on the emergency (backup) battery for the Telematic/Telephone Control Module.

ABS system, general information
The new Audi AS is equipped with the Bosch 5.3 ABS/EDL system as standard equipment.
A traction control system (ASR) may also be installed as optional equipment on vehicles with front wheel drive.
The ABS hydraulic system is divided diagonally (two circuits). The vacuum brake servo unit boosts the brakes pneumatically.





Hydraulic unit -a- and control module -b- are combined as a single unit. This is referred to as the hydraulic control unit.
The direct connection between these components reduces possible sources of malfunctions. The hydraulic control unit is not serviceable and must be replaced if malfunctioning.
Do not remove bolts connecting individual components of the hydraulic control unit.