Circuit/System Description (Without JL4)
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The electronic brake control module (EBCM) monitors the brake pressure sensor. The information the EBCM receives from the brake pressure sensor is sent through serial data circuits to the trailer brake control module (TBCM). The TBCM uses this information to perform trailer brake functions. The brake pressure sensor is mounted to the master cylinder.