P0744 Lexus Torque Converter Clutch Solenoid Valve Function
Possible causes
– 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
– Low transmission fluid level
– Dirty transmission fluid
Tech description
When the a transmission solenoid is working intermittent, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. 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.
What about the obd code?
The P0744 Lexus is detected when A/T cannot perform lock-up even if electrical circuit is good.
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P0744 Lexus Description
The Torque Converter Clutch (TCC) 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.
Lexus Vehicle:Lexus ES,Lexus GS,Lexus GX,Lexus HS,Lexus IS,Lexus LFA,Lexus LS,Lexus LX,Lexus RX,Lexus RX,Lexus SC,Lexus GS350,Lexus GS450H,Lexus IS250,Lexus GX460,Lexus IS350,Lexus LS460,Lexus LS600H,Lexus LX570,Lexus RX350