P0740: Torque Converter Clutch Circuit Malfunction
Can you still drive? Yes, you can drive, but fuel economy will suffer and the transmission may run hotter than normal. Avoid towing or heavy load conditions until repaired.
What Does P0740 Mean?
Code P0740 indicates an electrical problem in the torque converter clutch (TCC) solenoid circuit. The TCC locks the torque converter at highway speeds to eliminate slippage and improve fuel economy. When this circuit fails, the converter cannot lock, resulting in higher RPM at cruising speeds and reduced fuel efficiency. The issue may be the solenoid, wiring, or TCM.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Failed TCC solenoid
- Damaged wiring to TCC solenoid
- Faulty TCM driver circuit
- Corroded connector at transmission
- Internal torque converter failure
Symptoms
- Check engine light on
- Higher RPM than normal at highway speed
- Reduced fuel economy
- Slight shudder at highway cruising speed
- Transmission overheating in severe cases
Diagnostic Steps
- 1Monitor TCC engagement with scan tool at steady highway speed
- 2Check TCC solenoid resistance against specifications
- 3Inspect wiring harness at transmission connector for damage
- 4Test TCC solenoid operation using scan tool bidirectional control
- 5Check for power and ground at TCC solenoid connector
- 6If solenoid and wiring test good, check for internal converter damage
Recommended Parts & Tools
transmission fluid
transmission connector repair kit
OBD-II scan tool
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $150 - $1200 |
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Frequently Asked Questions
What does the torque converter clutch do?
The torque converter clutch (TCC) locks the torque converter at cruising speeds to create a direct mechanical connection between the engine and transmission, eliminating fluid slippage and improving fuel economy by 3-5%.
Can I ignore P0740?
While the vehicle is drivable, ignoring P0740 means reduced fuel economy and the transmission may run hotter. Over time, excess heat can shorten transmission life.
Is the TCC solenoid inside the transmission?
On most vehicles, yes. The TCC solenoid is typically located inside the transmission in the valve body area, though some designs allow access by dropping the transmission pan.
Community Fix Reports
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