P0850 Park/Neutral Switch Performance

P0850 code - With the engine running not equipped withh manual transmission. No vehicle speed, TPS, MAP, BARO or 5-volt reference DTCs active.

 Vehicle speed, engine speed and engine load calculations indicate that the vehicle is not in park or neutral. Set condition this DTC the Powertrain Control Module (PCM) receives and invalid park/neutral switch state message for 0.32 seconds. Default action the MIL light illuminate.

Possible causes P0850 code

- Transmission range sensor (TRS) wiring issues
- Communication failure between the PCM and the TCM
- Transmission Control module (TCM)

Diagnostic test P0850 code

Step 1. Check for an active DTC
This DTC could set during towing if the manual park release cable was not fully pulled and the pawl is in an intermediate position for too long. Start the engine and test drive the vehicle, with the scan tool read DTCs.
Diagnose and repair any CAN bus communication faults before continuing.

Is the DTC active or pending?

Yes, go to step 2.
No, perform the PCM intermittent condition.

Step 2. Check for Transmission Control Module (PCM)
With the scan tool, read TCM DTCs.

Does the TCM also have a DTC present for the Park/Neutral switch or TRS signal circuits?

Yes, perform the appropriate diagnostic procedure.
No, replace the Transmission Control Module (TCM). perform  the Powertrain Verification Test.

Share this post