DTC P0850-Park/Neutral Switch Performance: Notes

Fig 1: Park/Neutral Sense Circuit - Circuit Diagram

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

For a complete wiring diagram, refer to appropriate SYSTEM WIRING DIAGRAMS article.

Theory of Operation 

The Park Neutral switch rationality test is enabled only for vehicles equipped with a 4/5 speed automatic transmission. This diagnostic checks if the park/neutral switch is incorrectly stuck in the neutral position during driving conditions by comparing Vehicle Speed, Engine Speed, Throttle Position, and Pressure Ratio to the fail thresholds and by looking at the state of the Park/Neutral Switch. The stuck in drive condition is not explicitly checked as the starter relay does not energize and therefore render the vehicle inoperable. 

• When Monitored: 

  Continuously with the transmission in Park, Neutral, or Drive and NOT in Limp-in mode. 

• Set Condition: 

  This code will set if the PCM detects an incorrect Park/Neutral switch state for a given mode of vehicle operation. One trip fault. Three good trips to turn off the MIL. 

Always perform the PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding.