GM Service Manual Online
For 1990-2009 cars only
PNP Switch: This parameter indicates the range selection of 3 speed or 4 speed automatic transmission equipped vehicles. The parameter will display Park/Neutral for the Park or Neutral position of the gear selector. The parameter will display In Gear for the Reverse, Drive, or Low positions of the gear selector.

Starter Switch: This parameter displays ON when the powertrain control module (PCM) is receiving a signal indicating that the engine starter motor is cranking.