Possible causes

– Low transmission fluid level
– Dirty transmission fluid
– Faulty torque converter clutch solenoid valve
– Torque converter clutch solenoid valve harness is open or shorted
– Torque converter clutch solenoid valve circuit poor electrical connection

When is the code detected?

When the PCM detects a continuous open, short to ground or short to power in the TCC solenoid valve circuit, then DTC P0740 sets.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Transmission shift shock
– Vehicle may not shift into the highest gear

P0740 BUICK Description

The Torque Converter Clutch (TCC) solenoid valve is an electrical device that is used with the torque converter clutch pulse width modulation (TCC PWM) solenoid valve in order to control TCC apply and release. The TCC solenoid valve attaches to the transmission case assembly extending into the pump cover. The Powertrain Control Module (PCM) controls the solenoid by providing the ground path. The PCM monitors the throttle position (TP) voltage, the vehicle speed and other inputs in order to determine when to energize the TCC solenoid valve.