Wheel Speed Sensor

DESCRIPTION

Front
The front Wheel Speed Sensor (WSS) are a magnetic coil/pickup that mounts to the front steering knuckle. Each WSS produces an AC voltage signal which is transmitted to the Electronic Brake Control Module (EBCM) to indicate how fast the wheel is turning. The speed of the wheel is directly proportional to the frequency and amplitude of the wheel speed signal.

Rear
The rear WSS is an output of the Vehicle Control Module (VCM). The signal from the Vehicle Speed Sensor (VSS) is an input to the VCM and the VCM will output the vehicle speed signal to the EBCM for a rear wheel speed signal.

OPERATION
The WSS's use tone wheels to produce an AC voltage signal. Tone wheels are metal rings with teeth on the outside diameter. The AC voltage is produced as the teeth pass through the-magnetic field of the wheel speed sensor pole piece. Any imperfections in the tone wheels, such as a broken or missing tooth, can cause an inaccurate wheel speed signal.

Wheel Speed Sensor Calibration
The EBCM is capable of accepting wheel speed signals from several different size tire and wheel combinations. All vehicles are preprogrammed from the factory with the proper front tire size calibration. Whenever the EBCM is replaced and/or the tire size is changed, it is necessary to reset the tire size calibration in the EBCM. Once programmed, this calibration will remain even if the battery is disconnected or the EBCM is removed from the vehicle.