Circuit/System Verification
WARNING: This page is about a different car, the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
Key ON, engine OFF. The TCCM runs a 2 second bulb test on all indicators of the TCSCS at key ON.