Liftgate Release Switch
WARNING: This page is about a different car, the 2016 Ford Transit Connect. However, it is still accessible from the selected car via links, so may be relevant.
The liftgate release switch is a momentary contact switch that receives a voltage signal from the BCM. When the button is pressed, the input is routed to ground, signaling the BCM to release the liftgate latch. The release switch only operates when the doors are unlocked electronically or within 45 seconds of an initial press of the liftgate release button on a RKE transmitter.