Luggage Compartment Lid Latch
WARNING: This page is about a different car, the 2015 Lincoln MKS. However, it is still accessible from the selected car via links, so may be relevant.
The luggage compartment lid latch contains a switch (ground switches) that receive a voltage signal from the BCM through the luggage compartment bulb. When the luggage compartment lid is open, the switch routes the signal to ground.