Circuit/System Verification
WARNING: This page is about a different car, the 2009 GMC Envoy and 2009 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Ignition ON, observe the scan tool steering wheel controls (SWC) Switch Voltage parameter in the BCM data list. Pressing the switch should read voltage present, and drop to 0 volt when released.