Anti-Lock/Traction Control: Description

The Bosch-designed Anti-Lock Brake System (ABS) uses a hydraulic unit with 3 fast-switching solenoid valves, 3 speed sensors, an electronic control unit with overvoltage protection and a wire harness with relays. A Yellow ABS warning light comes on as ignition is turned on and goes out when engine is running. The ABS system is programmed to activate after 7.5 MPH.

When vehicle speed is more than 3 MPH, Built-In Test Equipment (BITE) checks ABS. If any fault is found, ABS warning light comes on again. When warning light goes on, ABS is switched off and conventional brake system takes over.

If battery voltage is less than 11 volts, when ignition is turned on and test speed exceeded, ABS remains off until alternator increases voltage to more than 11 volts. Warning light will then go out. After repairing ABS system, perform a light test to check system. Ensure light goes out after 7 MPH.

NOTE: The entire ABS system must be checked if repair includes any ABS component or if units are replaced following an accident.

NOTE: For more information on brake system, see DISC article.