Ford Focus mk3 ABS pin data and wire colors. Left front, right rear, left rear and right front speed sensor colors and wiring.
The ABS module continuously monitors brake pedal input, lateral vehicle motion and the rotational speed of each wheel. The PCM sends the brake pedal switch information to the ABS module over the High Speed Controller Area Network (HS-CAN) while the RCM sends lateral acceleration sensor information to the ABS module over a private High Speed Controller Area Network (HS-CAN). Wheel speed information is retrieved by the ABS module using 4 active wheel speed sensors. When the ABS module detects an impending wheel lock during a braking event, it modulates brake pressure to the appropriate brake caliper(s) or wheel cylinder(s) by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. Once the affected wheel(s) return to the desired speed, the ABS module returns the solenoid valves in the HCU to their normal position.
The ABS module has 2 self-test options, one is carried out using the scan tool and the other is carried out when the ignition is set to RUN. During either self-test the ABS module carries out a preliminary electrical check of the system sensors and activates the hydraulic pump motor for approximately one-half second. During this time, a buzzing or humming noise may be heard and a vibration may be felt in the brake pedal and is a normal condition. During the module initialized self-test, the pump motor check is carried out at approximately 10 km/h (6 mph). Any malfunction detected in the system causes the module to set a DTC, disable the ABS function and send a message over the High Speed Controller Area Network (HS-CAN) to the BCM. The BCM then sends a message to the IPC over the Medium Speed Controller Area Network (MS-CAN) to illuminate the ABS warning indicator. The base hydraulic power-assist braking system functions normally.