Operation - Ignition Circuit Sense
WARNING: This page is about a different car, the 2005 Dodge Magnum and 2005 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.
The ignition circuit sense input tells the PCM the ignition switch has energized the ignition circuit.
Battery voltage is also supplied to the PCM through the ignition switch when the ignition is in the RUN or START position. This is referred to as the "ignition sense" circuit and is used to "wake up" the PCM.