P0740
PowertrainTransmissionmoderate severityTorque Converter Clutch Circuit Malfunction
What P0740 Means
Malfunction in the torque converter clutch (TCC) solenoid circuit.
Symptoms
- Check Engine Light
- No lockup feel (higher RPM at highway)
- Poor fuel economy
- Transmission overheating
Common Causes
- Faulty TCC solenoid
- Wiring issue
- PCM driver failure
- Torque converter failure
Diagnostic Steps
- Test TCC solenoid resistance
- Check wiring
- Command TCC engagement with scan tool
- Monitor RPM drop during lockup command
Where to start: Replace TCC solenoid or repair wiring. Solenoid is often inside transmission.
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