OBD-II Trouble Code Description for P0740 GMC

Torque Converter Clutch Circuit/Open

What does this mean?

OBD2 Code P0740 GM definition:
The torque converter clutch solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Lock-up piston operation will then be controlled. When the torque converter clutch solenoid valve is activated, the torque converter lockup clutch will engage creating a 1 to 1 RPM ratio between the transmission input shaft and the rotational speed of the torque converter. Lock-up operation, however, is prohibited when A/T fluid temperature is too low. When the accelerator pedal is depressed (less than 2/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.

Symptoms

Possible sumptoms of OBD code P0740 GM
– Engine Light ON (or Service Engine Soon Warning Light) – Transmission shift shock – Vehicle may not shift into the highest gear

Causes

Possible causes of OBD code P0740 GM
– Low transmission fluid level – Dirty transmission fluid – Faulty torque converter clutch solenoid valve – Torque converter clutch solenoid valve harness or connectors – Torque converter clutch solenoid valve circuit is open or shorted The Error code is generally activated on detection of the following conditions: Diagnostic trouble code P0740 GM is detected when TCM detects an improper voltage drop when it tries to operate the solenoid valve.

Possible Solutions