Rear Compartment Lamp
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.
The inadvertent power relay also provides battery positive voltage to the rear compartment lamp. When the rear compartment is opened, its switch closes to provide a ground circuit and the rear compartment lamp illuminates. Ground is provided at G401.