Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Code P0740, Torque Converter Clutch: Notes
The Torque Converter Clutch (TCC) eliminates the loss of power to torque converter when cruise control is engaged. This allows the convenience of the automatic and the fuel economy of a manual transaxle. The main components of the system are 2 PCM controlled solenoids located inside the transaxle.
TCC is applied when the TCC apply solenoid coil is activated (on) resulting in a straight through mechanical coupling from engine to wheels. TCC is released when TCC apply solenoid coil is deactivated (off) allowing torque converter to operate in conventional manner (fluid coupling between engine and transaxle).
TCC PWM solenoid is used to vary hydraulic pressure to converter clutch regulator valve, allowing a smoother engagement of converter clutch.
Code P0740 will set when the following conditions are present.
- TP sensor throttle angle greater than 10 percent.
- Vehicle is in 3rd or 4th gear.
- VSS signal greater than 35 MPH for a 10 second minimum.
- TCC is commanded on by PCM.
- Engine RPM/vehicle speed ratio indicates TCC is not locked.
- Above conditions for over 10 seconds.
With Code P0740 set, PCM will not allow 4th gear and TCC operation, only 1st, 2nd, and 3rd gear operation. Code P0740 does not illuminate the Malfunction Indicator Light (MIL).
- Determines whether fault is caused by a bad solenoid or control circuit.
- Checks availability of battery voltage.
- Checks PCM's ability to pulse PWM solenoid on and Off.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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