Transmission Range Sensor Circuit Malfunction (PRNDL Input)
Diagnostic trouble code P0705 indicates that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) has detected a malfunction in the Transmission Range Sensor (TRS) circuit. The module sets this code when it receives multiple, conflicting, or no gear position inputs (such as Park, Reverse, Neutral, Drive) from the sensor.
This code is considered high severity because a faulty transmission range sensor can prevent the vehicle from starting (if it cannot detect Park or Neutral) or cause erratic and unsafe transmission shifting.
Common symptoms
- Check Engine Light illuminated
- Vehicle will not crank or start
- Harsh or erratic transmission shifting
- Transmission goes into 'limp mode' (stuck in one gear)
- Reverse lights do not illuminate when in Reverse
Likely causes
- Defective Transmission Range Sensor (TRS) / PRNDL switch
- Corroded, damaged, or loose wiring and connectors in the TRS circuit
- Misadjusted Transmission Range Sensor or shift cable
- Internal transmission valve body issues affecting the sensor (on models with internal sensors)
- Faulty Powertrain Control Module (PCM) or Transmission Control Module (TCM) (rare)
What to check before replacing parts
Scan for all DTCs and record freeze frame data.
Look for: Check if P0705 is the only code or if there are other transmission or communication codes that might indicate a broader electrical issue.
Visually inspect the Transmission Range Sensor, its connector, and the wiring harness.
Look for: Look for signs of corrosion, water intrusion, frayed wires, or loose connections at the sensor.
Verify the adjustment of the shift cable and the Transmission Range Sensor.
Look for: Ensure the mechanical linkage moves the sensor to the correct detents corresponding to the gear selector position inside the cabin.
Use a scan tool to monitor the Transmission Range Sensor PID data while moving the gear selector through all positions.
Look for: The scan tool should display the correct gear (P, R, N, D, etc.) matching the shifter position. If it shows multiple gears at once, 'unknown', or no change, the sensor or circuit is faulty.
Perform a continuity and voltage check on the TRS circuit using a multimeter.
Look for: Check for proper reference voltage, ground, and signal return to the PCM/TCM according to the manufacturer's wiring diagram. An open or short circuit indicates a wiring problem.
This page explains the generic P0705 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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