ECM Input EI74: Park/Neutral Circuit: Notes

The park neutral switch is a part of transmission gear selector switch. Pin "A" of the 6-way Weatherpack connector on the switch is park/neutral input for ECM. The park/neutral switch contacts are closed in Park or Neutral, shorting switch pin "A" to ground. In any other gear range, pin "A" is open to ground.

The ECM sends 12 volts to pin "A" of gear selector switch on circuit No. 434. When gear selector is in Park or Neutral, the 12-volt signal from ECM is shorted to ground, resulting in zero volts at ECM pin "A2".