Code
P1876
MITSUBISHI
P — Powertrain
Gearbox potentio#2 error(SRC Lo)
Views:
UK: 13
EN: 144
RU: 18
AI status
Completed
Completed
100%
Causes
- Damaged or failed gearbox potentiometer (position sensor) #2
- Wiring short to ground in the sensor signal circuit
- Poor or corroded connector/terminal at the sensor or ECU harness
- Lost or low reference voltage or bad ground to the sensor
- Intermittent open circuit in signal or return wiring
- Faulty transmission control module/ECU (less common)
Symptoms
- Check Engine/Transmission fault lamp illuminated
- Incorrect gear indication on dash or gear selection mismatch
- Transmission enters limp/failsafe mode or limited gears
- Harsh or reluctant shifting, inability to select certain gears
- Intermittent fault that may clear when connectors/mounts are moved
What to check
- Read stored DTCs and freeze frame/fault occurrence conditions with a scan tool
- Visual inspection of potentiometer #2 connector, pins and wiring for corrosion, damage or poor seating
- Backprobe sensor wiring with ignition ON and observe live data (sensor voltage) with scan tool
- Measure reference voltage and ground at the sensor connector with a digital multimeter
- Perform wiggle test on harness while watching live signal for intermittent drops
- Check for related codes (ECU supply, ground, other transmission sensors)
Signal parameters
- Reference voltage (sensor supply): approximately 5 V (varies by model)
- Expected sensor output range: roughly 0.5–4.5 V depending on lever position
- Short-to-ground/low threshold: signal near 0.0–0.2 V considered LOW/shorted
- Open-circuit indication: signal may float or read near 0 V when unplugged (compare with specification)
- Resistance of potentiometer should change smoothly through travel (ohm check)
Diagnostic algorithm
- Safety first: Park vehicle on level ground, inhibit engine run if required and apply parking brake.
- Retrieve freeze frame and note conditions when the code set (gear, speed, temperature, ignition state).
- Inspect the physical condition of potentiometer #2 connector and wiring harness at the transmission for corrosion, damage, pin push-out or water intrusion. Repair any obvious issues.
- With ignition ON (engine off), backprobe the sensor connector: verify reference voltage (≈5 V) and good ground at the harness. If reference is absent, trace supply back to ECU/fuse/relay.
- With key ON, monitor sensor signal voltage with scan tool or DMM while moving the gear lever through its range (if accessible). Signal should change smoothly within the expected range. If signal is stuck low, suspect short to ground or failed sensor.
- Measure potentiometer resistance (if removable) and confirm smooth variable resistance across travel. Replace sensor if resistance is open, shorted or shows dead spots.
- Perform a wiggle test on harness and connectors while watching live data to reproduce intermittent faults. Repair chafed wiring or broken conductors.
- If wiring and sensor check OK, inspect/repair grounds and harness routing to eliminate shorts. If wiring repairs are made, clear codes and road test to confirm.
- If all wiring and sensor tests pass and problem persists, consider ECU/TCU input circuit fault — verify with manufacturer service data and replace/control unit only after eliminating harness and sensor faults.
- Note: follow vehicle-specific service manual for pinouts, resistance/voltage specifications and safety procedures.
Likely causes
- Contaminated/corroded connector at potentiometer #2
- Chafed insulation causing signal wire to contact chassis ground
- Moisture ingress into sensor causing low output
- Broken internal potentiometer track producing low output
- Faulty reference (5V) supply or ground at ECU harness
Fault status
Status
SRC Lo — Gearbox potentiometer #2 signal detected below allowed threshold (low voltage/short to ground or lost reference). Stored when low-signal condition persists during monitoring.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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