Principles of Operation

The anti-lock brake system (ABS) module receives wheel speed readings from each wheel speed sensor and processes this information to determine if an ABS event is necessary. The wheel speed sensor electrically senses each tooth of the wheel speed sensor indicators as it passes through the wheel speed sensor's magnetic field.

The ABS module continuously monitors and compares the rotational speed of each wheel, and when it detects an impending wheel lock, modulates hydraulic brake pressure to the appropriate brake caliper. This is accomplished by the ABS module triggering the hydraulic control unit (HCU) to open and close the appropriate solenoid valves. Once the affected wheel returns to normal speed, the ABS module returns the solenoid valves to their normal position, and normal (base) braking resumes.

The ABS module is self-monitoring. When the ignition switch is turned to the RUN position, the ABS module will do a preliminary electrical check, and at approximately 12 km/h (8 mph) the pump motor is turned on for approximately one halfsecond. Any malfunction of the ABS will cause the ABS to shut off and the yellow ABS warning indicator to illuminate, however, normal power assisted braking remains.

The ABS module has the ability to store multiple DTCs in memory.