Principles of Operation
WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition switch is turned to the START position and the vehicle is in the NEUTRAL or PARK position, the starter relay switches power to the starter solenoid causing the starter motor to engage, turning the engine at a speed fast enough to permit the engine to start.