Antilock Braking System
General Repair Instructions and Safety Precautions
ABS is basically maintenance-free. Specialized knowledge is required to carry out service or repair work on this system. Failure to read and follow the safety precautions that follow may result in system damage and loss of vehicle safety.
- Before disconnecting the ABS control module connector, be sure the ignition is switched off. Heat and sparks can cause damage.
- The ABS control module connector must be disconnected before carrying out any welding operations with electrical welding equipment on or near the vehicle.
- Remove the ABS control module before exposing the vehicle to high temperatures, as in a paint drying oven. The temperature must never exceed 90°C (194°F), and should not exceed 85°C (185°F) for more than two hours.
- Disconnect the battery negative terminal before charging the battery, and before removing the ABS hydraulic unit.
- When reconnecting the battery, make sure the terminals are tightened properly.
- Do not drive the car with the test equipment connected SAFETY PRECAUTIONS AND TROUBLESHOOTING .
Wheel/tire specifications:
- Do not use a small size temporary spare tire on vehicles equipped with ABS.
- Always use a complete set of wheels and tires of matching size on ABS-equipped vehicles.
ABS Repairs
Carry out the complete testing procedure (using the most up-to-date tester available) after any repairs involving:
- ABS hydraulic unit
- ABS control module
- ABS wheel speed sensors
- ABS wiring harness
It is also necessary to carry out the complete test procedure if, because of accident damage, the following components have been replaced:
- Brake lines
- Brake pressure regulators
Non-ABS Repairs
After repairs to the brake system that do not affect the anti-lock system components, perform the following operational tests to the ABS:
-- Switch ignition ON.
- ABS warning light in instrument panel should light up
-- Drive vehicle at speed above 4 mph (6 km/h).
- ABS warning light must not light up
Perform the test described above after any work in which the following components were repaired or replaced:
- Brake pads and/or brake discs
- Brake hoses
- Brake servo or master cylinder
- Brake lines and parking brake components
The ABS should not operate during normal braking, but must activate automatically when wheel "lock-up" or "skid" conditions are detected. During the final test drive, ABS function must be tested. Safely apply brakes in such a way that the ABS system will activate.