Wheel Speed Sensors
An active wheel speed sensor is installed in each wheel hub. They give a rotational speed signal from each road wheel to the Anti-lock Brake Control (ABS) control module. The head of each front wheel speed sensor is positioned close to a magnetic encoder ring incorporated into the inboard seal of the wheel bearing. The head of each rear wheel speed sensor is positioned close to a magnetic encoder ring incorporated into the rear wheel bearing assembly. A fly lead connects each wheel speed sensor to the vehicle wiring harness.
All of the wheel speed sensors have a signal and a return connection with the ABS control module. When the ignition is ON, the ABS control module supplies a signal feed to the wheel speed sensors and monitors the return signals. Any rotation of the road wheels induces current fluctuations in the return signals. Return signals are converted into individual wheel speeds and an overall vehicle speed by the ABS control module. The ABS control module broadcasts the individual wheel speeds and the vehicle speed for using them by the other systems. This signal transmission is made with the help of the High Speed (HS) Controller Area Network (CAN) chassis systems bus.
The ABS control module can detect a wheel speed sensor fault. If a fault occurs, the 'ABS FAULT' message appears in the Instrument Cluster (IC) message center and an amber warning indicator comes on.