Transmission Position Sensor/Switch: Testing and Inspection

Chart 24B - Park/Neutral Circuit (P/N) Circuit:

Wiring Diagram for Chart 24B - Park/Neutral P/N Circuit:

CHART 24B - PARK/NEUTRAL (P/N) CIRCUIT

Circuit Description:


The P/N switch is connected to the transmission gear selector. The switch is closed when the gear selector is in Park or Neutral and open for all other ranges. One side of the switch is connected to the ECM which supplies a buffered 12 volts. The other side of the switch is connected to ground. The P/N switch state is an input to the ECM. When the voltage at ECM Terminal "H" is high (12 volts), the ECM allows activation, at the proper time, of other controls such as TCC, EST, VSS, ISC (where applicable) and others.


Test Description: Step numbers refer to step numbers on diagnostic chart.

1. Checks for good P/N circuit. When the switch is closed in Park and Neutral, the voltage across the P/N switch terminals should be low, usually less than 1 volt. When the switch is open in Drive and Reverse, the voltage should be about battery voltage. "SCAN" step state should change between Park and Neutral.


2. This step separates a faulty switch, or switch adjustment, from a faulty electrical circuit or ECM. Normal voltage across the terminals of the connector, removed from the P/N switch, should be about battery voltage.