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DTC - Diagnostic Trouble Codes information

P0743

Powertrain Codes

P0743 - KIA - Torque Converter Clutch System Circuit Malfunction

Symptoms

- Engine Light ON (or Service Engine Soon Warning Light)

Possible Causes

- Faulty torque converter clutch solenoid valve - Torque converter clutch solenoid valve harness or connectors - Torque converter clutch solenoid valve circuit is open or shorted - Low transmission fluid level - Dirty transmission fluid

When Detected

By performing a voltage drop test, the ECM detects that the TCC solenoid circuit is open or shorted.

Tech Notes

This is an electrical problem code. Could be a problem to the harness to the TCC solenoid, the TCC solenoid connector or the TCC solenoid it self.

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.