Anti-Lock Braking System

General Information The Anti-lock Brake System (ABS), which is standard equipment on some models, controls wheel rotation speed during braking. A sudden deceleration of one wheel, indicating the start of wheel lock, causes the ABS to reduce or completely shut off brake pressure to that wheel.

The main components of the system are the wheel speed sensors, the electronic control unit and the hydraulic modulator.

Each wheel has its own speed sensor with a pulse ring located on the outer joint of the drive shaft or on the rear wheel hub. The sensors monitor wheel rotation speed and are able to determine when there is a risk of wheel lock (low rotation speed).

Sensor information is sent to the electronic control unit, which actuates the solenoid valves in the hydraulic modulator. The solenoid valves limit fluid supply to any caliper if the corresponding wheel is about to lock.

If a malfunction occurs in the system, the electronic control unit turns on the warning light on the instrument panel and disables the ABS. To simplify fault diagnosis, the system is equipped with an on-board diagnostic function. In case of a malfunction, the electronic control unit stores a number of signals (trouble codes) for later reading through the diagnostic connector located in the engine compartment.