Starting System - Without Intelligent Access (IA): Overview
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 starter system controls the cranking of the engine. The starter motor is enabled by the starter relay when the relay is activated by the PCM . The PCM receives inputs from the ignition switch, BCM Run/start relay and TR sensor before activating the starter relay to crank the engine.