Circuit Description

ECT ECU uses signals from direct clutch speed sensor, airflow meter, Throttle Position (TP) sensor and crankshaft position sensor to monitor engagement of Torque Converter Clutch (TCC). ECT ECU compares engagement condition of TCC with lock-up schedule in memory to detect mechanical trouble of solenoid, valve body and torque converter. DTC is set when TCC lock-up does not occur at appropriate speed, or lock-up does not release at appropriate speed. Possible causes are:

• Lock-up solenoid is stuck open or closed.
• Valve body clogged or valve stuck.
• TCC malfunction.