Standard ABS

The ABS module receives front wheel speed information directly from the front wheel speed sensors and rear wheel speed information from the PCM over the high-speed controller area network (HS-CAN) bus. The PCM receives the rear wheel speed senor information from the transmission output shaft speed (OSS) sensor. The ABS module then processes this information, along with other sensor inputs, to determine if an ABS event is necessary. The front wheel speed sensors sense each tooth on the sensor ring as it passes through the magnetic field of the wheel speed sensor. The OSS is a Hall-effect type sensor and senses the gear teeth on the park gear as they pass through the magnetic field of the sensor.

The ABS module continuously monitors and compares the rotational speed of each front wheel and the speed of the transmission output shaft. When the ABS module detects an impending wheel lock, the ABS module commands the hydraulic pump motor on and commands the hydraulic control unit (HCU) to open and close the appropriate solenoid valves to modulate the brake pressure to the individual brake caliper(s). Once the affected wheel(s) return to the desired speed, the ABS module commands the HCU to return the solenoid valves to their normal position and normal base brake operation is restored.

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. At approximately 20 km/h (12 mph), the pump motor is turned on for approximately 1/2 second. Any ABS malfunction will cause the module to deactivate the system and the ABS warning indicator to illuminate; however, normal power-assisted braking remains.