Ignition Switch - Conventional
WARNING: This page is about a different car, the 2016 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
The ignition switch is a multiple position rotary switch that is controlled by a lock cylinder and a key. The ignition switch is monitored by the BCM, which controls the voltage to the various electrical systems depending on input from the ignition switch.
The key removal inhibit solenoid (internal to the ignition switch) is an electronically controlled solenoid that prevents the ignition lock cylinder from being turned to the OFF position unless the selector lever is in the PARK position. This also prevents the key from being removed from the ignition lock cylinder.