Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Chart 24B - Park/Neutral Circuit (P/N)
The P/N switch is closed when gear selector is in Park or Neutral. One side of switch is connected to ECM which supplies a buffered 12 volts. The other side is grounded. The P/N switch is an input to the ECM. When voltage at ECM terminal "H" is high (12 volts), ECM allows activation, at proper time, of other controls such as TCC, EST, VSS and others.
- This test checks for good P/N circuit. When the switch is closed in Park and Neutral, voltage across P/N switch terminals should be low, usually less than 1 volt. When the switch is open in Drive and Reverse, voltage should be about battery voltage.
- This step separates a faulty switch or switch adjustment, from a faulty electrical circuit or ECM. Normal voltage across the terminals of the connector, when removed from P/N switch, should be about battery voltage.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.