Park/Neutral Switch
NOTE:
Vehicle should not be driven with Park/Neutral switch disconnected as idle quality may be affected.
The Park Neutral (P/N) Switch is part of transmission neutral safety back-up switch (NSBU). See Fig 1 . Pin "A", of six-way weather pack connector on NSBU switch, is Park/Neutral switch contact. The Park/Neutral 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 ECM sends 12 volts to pin "A" of NSBU. When gear selector is in park or neutral, 12 volt signal from ECM is shorted to ground, resulting in 0 volts at ECM.
In reverse or forward gears switch will be open, resulting in 12 volts at ECM.
The switch test E174 can be used to check P/N switch for proper operation. An inoperative P/N switch could cause improper idle speed, cruise control or VCC operation.