Transmission Position Sensor/Switch: Description and Operation
PARK/NEUTRAL POSITION SWITCHPNP SIGNAL
This signal is sent to the Engine Control Module (ECM) from the Park/Neutral Position (PNP) switch whenever the manual selector lever is in the "P" or "N" position (automatic transmission models only). The ECM uses this signal as one of the signals to control fuel injection timing and Idle Air Control (IAC) valve operation.