Vehicles that are equipped with an automatic transmission have a torque converter that goes between the engine and transmission. This increases the engine's torque output, as well as driving the rear wheels. Both, the engine and the transmission are connected by this fluid coupling system with which the torque increases, resulting in equalized speeds creating a stall speed where the actual engine RPM and transmission input RPM are 90% efficient.
The TCC (Torque Converter Clutch) is used by the PCM (Powertrain Control Module) or TCM (Transmission Control Module) to bring the hydraulic fluid and achieve the coupling of the torque converter clutch, this to make the coupling solid and effective.
When diagnostic code P0740 OBD2 is set, it indicates that the TCM/PCM (you must refer to the manufacturer's diagrams to find out which system your vehicle uses) has detected a fault in the torque converter clutch solenoid circuit.
Factors that may lead to the establishment of DTC code P0740 are
Maybe there's an incorrect transmission fluid level.
The TCC (Torque Converting Clutch) solenoid may be defective.
The Torque Converter Clutch is probably defective.
Internal damage to the transmission.
Possible solutions of the DTC code P0740 Generic
When faced with fault code P0740 OBDII, you must do the following:
Inspect the transmission fluid, make sure the level and conditions are correct, add more fluid, or change it as needed.
Check all cables leading to the transmission. If you find problems such as worn cables or cables that are rubbing against other components, you should make the necessary repairs or replace them if necessary. Also, check the connectors and make sure there is a good electrical connection.
Changes the TCC (Torque converter clutch) solenoid.