Transmission Position Sensor/Switch: Description and Operation

TRANSMISSION [1][2]PARK/NEUTRAL SWITCH-PCM INPUT
The park/neutral switch is located on the transmission housing and provides an input to the Powertrain Control Module (PCM). This will indicate that the automatic transmission is in Park, Neutral or a drive gear selection. This input is used to determine idle speed (varying with gear selection), fuel injector pulse width and ignition timing advance. It is also used as a condition for speed control operation.