Early Production ABS

A wheel speed sensor (WSS) is present at each wheel and transmits wheel speed information to the Anti-lock Brake Control Module (ABM) by means of a small AC voltage. This voltage is generated by passing a toothed sensor ring (tone wheel) past a stationary magnetic sensor. The signal is transmitted to the ABCM through a pair of twisted wires in the wiring harness.

The front wheel sensor is attached to a boss in the steering knuckle. The tone-wheel is part of the outboard constant velocity joint. The sensor for the rear wheel is mounted to the caliper adaptor and the tone-wheel is an integral part of the wheel hub.

All four wheel speed sensors are serviced separately. The rear tone wheels are serviceable as wheel hub assemblies. The front tone-wheels are serviceable as outboard constant velocity joint assemblies.