Circuit/System Verification
WARNING: This page is about a different car, the 2017 GMC Acadia Limited, 2017 Chevrolet Traverse, and 2017 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
Command the Rear Defog Request ON and OFF with the scan tool. The rear window defogger should turn ON and OFF when changing between the commanded states.