Code
P0740
GWM
P — Powertrain
- Malfunction in the clutch chain
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in the TCC solenoid circuit
- Corroded, loose or damaged connector at the transmission/TCM
- Failed torque converter clutch solenoid (stuck, intermittent, open coil)
- Low or dirty automatic transmission fluid causing incorrect hydraulic pressure
- Faulty transmission control module (TCM) or PCM output driver
- Blown fuse or faulty relay supplying the TCC circuit
Symptoms
- Transmission may not lock torque converter — reduced fuel economy
- Harsh or soft shifts, torque converter slipping or shuddering
- MIL/Check Engine Light illuminated and stored P0740
- Possible limp-in/limp-home mode or derate of transmission performance
- Unusual transmission noise under load
What to check
- Retrieve freeze frame and live data with a capable scanner (TCC duty, commanded state, actual engagement, transmission line pressure, gear, engine RPM, vehicle speed)
- Check for additional transmission-related DTCs (P0741, P0750–P0770, P0730, etc.)
- Visually inspect TCC solenoid connector and wiring for damage, chafing, corrosion or pin push-out
- Verify battery voltage and ground integrity at ignition on and while cranking
- Check transmission fluid level and condition (color, smell, debris)
- Inspect relevant fuses and relays for the TCC/TCM circuit
Signal parameters
- TCC solenoid coil resistance (typical range): roughly 2–30 ohms (manufacturer-specific — consult vehicle manual)
- Supply voltage to solenoid with ignition ON: approximately battery voltage (~11–14 V)
- Command signal from TCM: switched ground or PWM duty cycle (0–100%) depending on design
- Expected change in line pressure or engagement status when TCC is commanded ON (monitor via scanner)
- No open circuit (OL) or short to ground/power on continuity checks between TCM pin and solenoid
Diagnostic algorithm
- Connect a professional scanner and read stored codes and freeze-frame data. Note operating conditions when code set (gear, speed, RPM, temp).
- Inspect the TCC solenoid connector and visible wiring at the transmission for corrosion, water intrusion, pin damage, or rubbing — repair as needed.
- With ignition OFF, backprobe the solenoid connector: check coil resistance across solenoid pins. Compare to vehicle-specific spec; replace solenoid if out of range or open.
- With ignition ON and engine off, check for battery voltage at the supply pin of the solenoid connector. With engine running and TCC commanded, monitor control side for ground switching or PWM using a scope or multimeter.
- Wiggle-test wiring while monitoring live data for intermittent faults. Repair any intermittent shorts/opens.
- Verify transmission fluid level and condition. If low/contaminated, correct level and flush/replace fluid and filter as required, then retest.
- Check fuses/relays and TCM grounds. Repair poor grounds or power issues.
- If electrical tests pass but TCC still does not operate, perform a hydraulic pressure test to confirm line pressure and apply-pressure to TCC circuit per factory procedure — inspect for internal valve body or converter issues.
- If all wiring, solenoid, hydraulic and mechanical checks pass, consider TCM/PCM output driver failure — verify by substitute TCM or bench tests per manufacturer guidance before replacement.
- Clear codes and road-test under the same conditions to confirm repair. Monitor for reappearance of P0740 and related symptoms.
Likely causes
- TCC solenoid electrical fault (open/short or connector corrosion)
- Failed TCC solenoid
- Low/contaminated transmission fluid or insufficient line pressure
- Damaged wiring harness at the transmission
Fault status
Status
P0740: Torque Converter Clutch (TCC) Circuit Malfunction — ECU/TCM detected improper control or feedback from the TCC circuit. Check wiring, connector, TCC solenoid, transmission fluid and control module.
Repair difficulty: Medium
Diagnostic time: 1.0-3.5 hours
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