Transmission Position Sensor/Switch: Description and Operation

PRNDL-P/N Switch:

PCM Wiring:

PURPOSE
The PARK/NEUTRAL (P/N) switch is part of the transmission Neutral Safety Back Up (NSBU) switch.

OPERATION
Pin A of the six-way weather pack connector, on the NSBU switch, is the P/N switch contact. The P/N switch contacts are closed in park or neutral, shorting NSBU switch pin A to ground. In any other gear range, pin A is open. The Electronic Control Module (ECM) sends 12 volts to pin A of the NSBU. When the gear selector is in park or neutral, the 12 volt signal from the ECM is shorted to ground, resulting in 0 volts at the ECM. In reverse or forward gears the switch will be open, resulting in 12 volts at the ECM.


DIAGNOSTIC NOTES
The input switch test code EI74 can be used to check the P/N switch for proper operation. An inoperative P/N switch could cause improper idle speed, cruise control, or Viscous Converter Clutch (VCC) operation.