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 trailer brake control module (TBCM) monitors for faults on the trailer brake solid state relay (SSR) output auxiliary supply voltage circuit for fault for a short to ground, short to battery, or open circuit.