Starting System
WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
The starting system controls the cranking of the engine. The PCM energizes the starter relay when it receives inputs from the ignition switch, automatic transmission, and the BCM. When the starter relay is energized it applies power to the starter motor which cranks the engine.