Circuit/System Verification
WARNING: This page is about a different car, the 2011 Chevrolet Volt. However, it is still accessible from the selected car via links, so may be relevant.
Ignition ON, observe the scan tool Trunk Lid/Liftgate Window Exterior Unlatch Switch parameter while pressing and releasing the S46 liftgate handle switch. The parameter should change between Active and Inactive each time the switch is pressed and released.