Park/Neutral Switch
NOTE:
Vehicle should not be driven with Park/Neutral switch disconnected as idle quality may be affected.
The Park/Neutral 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 contacts. 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 PCM sends 12 volts to pin "A" of NSBU. When gear selector is in park or neutral, 12 volt signal from PCM is shorted to ground, resulting in 0 volts at PCM. In reverse or forward gears switch will be open, resulting in 12 volts at PCM.
The input switch test Code EI74 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.