Circuit/System Description
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The User Gain Switch consists of 2 control buttons: Gain Up, and Gain Down. The output signal from the trailer brake controller switch is connected, and monitored by trailer brake control module (TBCM).
The TBCM monitors the circuit fault for User Gain Switch input for faults that includes short to GND, short to battery, and open circuit. This DTC will also be reported when fault is detected in TBCM ground circuit.
The TBCM also monitors the input signal validity from the User Gain Switch.