Ignition Sense
WARNING: This page is about a different car, the 2003 Dodge Grand Caravan, 2003 Dodge Caravan, 2003 Chrysler Voyager, and 2003 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.
The ignition sense input informs the powertrain control module that the ignition switch is in the crank or run position.