Seville V8-273 4.5L (1989)
Transmission Position Switch/Sensor: Description and Operation
Park/Neutral (P/N) Switch
Park/Neutral Safety Switch
The Park/Neutral (P/N) switch is part of the transmission Neutral Safety Back Up switch (NSBU). 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. 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.
