Circuit/System Verification
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Ignition ON, command the sliding rear window to OPEN/CLOSE by pressing the front and rear side of the sliding rear window switch. The sliding rear window should OPEN and CLOSE as commanded.