Circuit/System Description
WARNING: This page is about a different car, the 2011 GMC Sierra, 2011 GMC Cab & Chassis Sierra, 2011 Chevrolet Silverado, and 2011 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The radio receives a vehicle speed signal from the electronic brake control module (EBCM) in order to correlate actual vehicle speed to the movement of the vehicle calculated by the navigation system and reported serial data.