Circuit/System Verification
WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
Ignition ON, observe the scan tool Trunk Ajar Switch parameter while opening and closing the rear compartment lid, the parameter should change between Trunk Closed and Trunk Ajar.