Meaning

The TCM has detected an electrical fault in the transmission range sensor (TRS) circuit, also known as the PRNDL switch or neutral safety switch. The sensor informs the TCM of the driver-selected gear position (P, R, N, D, L). An electrical fault prevents the TCM from determining the correct selector position.

Common causes

• Faulty or mechanically misadjusted transmission range sensor (TRS)
• Open circuit or short circuit in the wiring between the TRS and TCM
• Oxidized, loose, or damaged TRS connector
• Missing or interrupted TRS supply voltage or ground
• Broken internal TRS wiring or loose mechanical linkage connection
• Internal TCM fault on the TRS input channel

Symptoms

• Engine or transmission warning lamp illuminated
• Starter motor does not crank in Park or Neutral
• Transmission stuck in limp mode
• Reverse or other gears unavailable or not recognized
• PRNDL indicator on instrument cluster absent or incorrect
• Multiple simultaneous transmission position fault codes

Severity

What to do

1. Check and correct the mechanical adjustment of the TRS on the shift shaft to manufacturer specification
2. Measure TRS supply voltage, ground, and output signal with a multimeter
3. Inspect TRS connector and wiring for visible damage, oxidation, or recessed pins
4. Use a scan tool to monitor TRS values in real time while moving the selector through all positions
5. Replace the TRS if it fails testing; if wiring is intact and TRS checks out, inspect the TCM

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