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?

Diagnostic trouble code P0740 is detected when TCM detects an improper voltage drop when it tries to operate the solenoid valve.

Symptoms

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

P0740 Description

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.

P0740 Information for specific makes

P0740 SATURN
P0740 CADILLAC
P0740 ACURA
P0740 AUDI
P0740 BMW
P0740 CHEVROLET
P0740 CHRYSLER
P0740 DODGE
P0740 FORD
P0740 GMC
P0740 HONDA
P0740 HYUNDAI
P0740 INFINITI
P0740 ISUZU
P0740 JEEP
P0740 KIA
P0740 MAZDA
P0740 MITSUBISHI
P0740 NISSAN
P0740 PONTIAC
P0740 BUICK
P0740 SUBARU
P0740 SUZUKI
P0740 VOLKSWAGEN