Transmission Position Sensor/Switch: Description and Operation

Park/Neutral Position Switch




Circuit Description
The park/neutral position (PNP) switch contacts are a part of the selector position switch. The contacts are closed to ground in park and neutral and open in the drive ranges.

The engine control module (ECM) supplies ignition voltage through a current limiting resistor to the signal wire and senses a closed switch when the voltage on the signal wire drops to less than 1 volt. The ECM uses the PNP signal as one of the inputs to control idle air and spark timing.

Steps 1 - 12:

Test Description
The number(s) below refer to step(s) on the diagnostic table.
1. Checks for the park/neutral position (PNP) switch closed to ground in the park position. Different makes of scan tools will read park/neutral differently. Refer to the tool operations manual for the type of display used.
2. Checks for an open PNP switch in the drive range.