Park/Neutral Switch Failure

Name of Code:
Park/neutral Switch Failure

When Monitored:
With the transmission in park, neutral, or drive, and the transmission not in Limp-in mode.

Set Condition:
If the transmission is in Park or neutral, the engine must be cranking. If the transmission is in drive, the vehicle speed must be above 50 mph, the rpm must be between 1,985 and 4,480, the TP sensor must not be closed, and the MAP must be above 66%.

Theory of Operation:
The park/neutral position switch is used to communicate the state of the transmission to the idle air control (IAC) motor via the PCM. The IAC motor needs this information in order to determine the target idle speed. The IAC motor holds the Idle speed at 600 rpm in park or neutral, while it increases the engine speed to about 800 rpm when the transmission is shifted into drive. Spark also is advanced in park or neutral position, while it is retarded in drive position.

Possible Causes:
- Connector terminals/wires
- Disconnected wiring harness
- Park/neutral position switch failure
- Mechanical transmission problem
- Powertrain control module failure