Circuit/System Description
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The vehicle speed sensor (VSS) also called the output speed sensor (OSS) creates a AC voltage signal that increases in frequency as vehicle speed increases. The transmission control module (TCM) receives and process this signal. The TCM provides a digital VSS signal on the data communication line to the engine control module (ECM) and other controllers connected to the data line. The electronic control module (ECM) converts the data from the vehicle speed sensor to a 128K pulses/mile signal. The electronic brake control module (EBCM) uses the vehicle speed signal from the ECM in order to calculate the rear wheel speed.