P0740 – Torque converter clutch (TCC) solenoid – circuit malfunction

By John Kershaw (Contact Me)
Last Updated 2016-08-23
Ed.D, PhD Philosophy, BSME

Table of Contents

1. What Does Code P0740 Mean?
2. What are the common causes of code P0740 ?
3. What are the symptoms of code P0740 ?
4. Codes Related to P0740
5. Get Help with P0740

What Does Code P0740 Mean?

DTC P0745: When the transmission solenoid malfunctions, in most cases the problem is not the electrical part of the solenoid; the problem is generally foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. The line pressure solenoid valve regulates the oil pump discharge pressure to suit the driving condition in response to a signal sent from the TCM (Transmission Control Module) or PCM (Powertrain Control Module).

NOTE: Whenever diagnosing a 700 series DTC (Diagnostic Trouble Code) with a transmission, transfer case or other driveline components, check for a DTC under chassis and body systems, not just under “P” or powertrain/engine or emission control type codes. Module communications DTCs are “U” codes. These are most often found when looking for DTCs under chassis or body systems. Chassis related codes are labeled “C” and body system related codes are labeled “B” codes and these can cause drivetrain issues if they affect a sensor that is also used by the heating and air conditioning system.

DTC P0745 sets when the PCM or TCM has detected an abnormality in the electronic pressure control solenoid circuit. Computer controlled automatic transmissions use variable amounts of hydraulic pressure to provide shifting and TCC (torque converter clutch) operation.

What are the common causes of code P0740 ?

• Low, dirty or contaminated transmission fluid If the transmission fluid is very dirty, it is recommend changing the transmission fluid and if possible removing the transmission pan for further diagnosis.
• Excessive debris or metal particles on the transmission pan could be an indication that there is a transmission mechanical failure and that the transmission will need to be rebuilt or replaced.
• Defective pressure control solenoid
• Line pressure solenoid valve harness is open or shorted
• Line pressure solenoid valve circuit poor electrical connection
• Fluid blockages inside the transmission fluid passages
• Mechanical internal transmission failures
• Defective PCM or TCM but this is rare

What are the symptoms of code P0740 ?

• MIL (Malfunction Indicator Lamp [Check Engine & Service Engine Soon])lights on with stored historical P0745
• TCC does engage/disengage
• Disabled shifting function with engine stall when coming to a stop
• Harsh shifting, transmission slippage, transmission overheating
• Fuel efficiency concern

Codes Related to P0740

• Transmission slippage codes often accompany this code like DTC P0894

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