Circuit/System Description
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The vehicle speed sensor, also called the output shaft speed sensor creates an AC voltage as the rotor teeth pass through the magnetic field of the sensor. The transmission control module (TCM) converts the AC voltage into a vehicle speed signal, which is used to determine shift timing and torque converter clutch scheduling. The TCM also provides a replicated transmission output speed signal to the engine control module (ECM).
The ECM converts the data from the output speed signal to a 128K pulses/mile engine speed signal. The electronic brake control module (EBCM) uses the signal from the ECM in order to calculate the rear wheel speed.