Circuit Description
WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
As the front wheels spin, the wheel speed sensors produce an AC signal. The EBCM uses the frequency of the AC signal to calculate the wheel speed. The PCM converts the data from the vehicle speed sensor to a 128k pulses/mile signal. The EBCM uses the vehicle speed signal from the PCM in order to calculate the rear wheel speed.