Circuit/System Verification
WARNING: This page is about a different car, the 2011 GMC Acadia, 2011 Chevrolet Traverse, and 2011 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
Ignition ON, transmission in REVERSE, observe the scan tool Sensor Feed Voltage Output parameter. The reading should be between 6.3-10.4 V.