Liftgate Ajar Switch
WARNING: This page is about a different car, the 2014 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
The liftgate ajar switch (ground switch) receives a voltage signal from the BCM . When the liftgate is closed, the liftgate ajar switch is closed, routing the signal to ground. When the liftgate is opened, the liftgate ajar switch opens.