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 TBCM runs this diagnostics to check whether there is a fault on the internal TBCM 5 volt references used to monitor the User Gain switch circuits. This diagnostics checks if the circuits' 5 volt references is within a range for normal operation.