Without Intelligent Access (IA)
WARNING: This page is about a different car, the 2014 Lincoln MKX and 2014 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.
When the exterior liftgate switch is pressed, the Body Control Module (BCM) sends a signal to the LTM over a hardwired circuit which opens the liftgate only when the doors are unlocked.