Starting System
WARNING: This page is about a different car, the 2018 Lincoln MKC. However, it is still accessible from the selected car via links, so may be relevant.
The starting system controls the cranking of the engine. When the PCM receives inputs from the ignition switch, automatic transmission, run/start relay and the BCM it then energizes the starter relay. When the starter relay is energized it applies power to the starter motor which cranks the engine.