Code
P0708
GWM
P — Powertrain
- High Transmission Sensor
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring (short to battery voltage) in the transmission position/range sensor circuit
- Corroded, bent or pushed-off connector terminals at sensor or TCM/PCM
- Faulty transmission position/range sensor (TRS/neutral safety switch)
- Poor ground or intermittent ground connection
- Faulty TCM/PCM input circuit
- Aftermarket electrical work or water intrusion damaging harness
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Incorrect or no gear indicator on dash (PRNDL incorrect)
- Car may not start in Park/Neutral or shows starter interlock issues
- Erratic or harsh shifting, or transmission stuck in limp/limitation mode
- Reduced engine power or drivability restrictions
What to check
- Retrieve freeze-frame and live data with an OBD-II scan tool; note sensor voltage/PRNDL status
- Visual inspection of transmission connector, wiring harness and grounds for corrosion, damage, or pin pushed out
- Backprobe sensor signal, reference and ground with ignition ON (engine OFF) to measure voltages
- Check continuity between sensor connector and TCM/PCM, and for short to battery (12V) or short to ground
- Swap with known-good sensor only if verified by bench/voltage checks or follow manufacturer procedures
- Clear codes and attempt to reproduce after repairs
Signal parameters
- Reference voltage (typical): ~5.0 V (varies by manufacturer) present at connector with key ON
- Expected signal voltage range: ~0.0–5.0 V depending on gear; a 'high' fault often means signal > ~4.5 V or near battery voltage
- Short to battery detection: signal reading near 12 V indicates short to B+
- Open/short to ground: signal reading at or near 0 V
- Resistance (sensor to ground) and between signal and reference should match factory spec — if unknown, compare to good unit
Diagnostic algorithm
- Connect a capable scan tool, read P0708 and any related codes; record live PRNDL/transmission position sensor data.
- Visually inspect the sensor connector, harness along transmission, and TCM/PCM connector for damage, corrosion, or water ingress.
- With ignition ON (engine OFF) backprobe the sensor connector: verify reference voltage (≈5V) and ground present. Record signal voltage.
- If signal is high (>≈4.5V or near battery), disconnect the sensor: if signal goes to open-circuit value (usually open/float), suspect short to B+ in harness. If signal drops to expected value, suspect sensor.
- Check continuity between the sensor signal pin and the module input pin; check for short to battery (measure continuity between signal wire and battery + with power removed) and short to ground.
- Wiggle test wiring while monitoring signal for intermittent faults. Repair any damaged wiring, terminals, or connectors found.
- If wiring and connectors are good, replace the transmission position/range sensor following manufacturer procedure and re-test.
- If fault persists after sensor and harness repairs, test/replace TCM/PCM or follow manufacturer module diagnostic flow (may require reflashing or replacement).
- Clear codes, take test drive or reproduce conditions to confirm repair and ensure code does not return.
Likely causes
- Damaged connector or corroded terminals at the transmission range sensor
- Short to battery voltage on the signal wire (pin sees 12V instead of reference)
- Failed transmission position sensor
- Loose or corroded ground at transmission or module
- Internal module fault (less common)
Fault status
Status
Transmission position (range) sensor circuit reporting higher-than-expected voltage. The vehicle may show incorrect gear selection, not start in Park/Neutral, or enter limp mode. Inspect wiring, connectors, sensor and module input.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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