Park/Neutral Position Switch
WARNING: This page is about a different car, the 2003 GMC Savana and 2003 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
The Park/Neutral Position (PNP) switch is connected to transmission gear selector and signals PCM when transmission is in Park or Neutral. PCM uses this information for determining control of ignition timing, Torque Converter Clutch (TCC) and idle speed.