Circuit Description

Lock-up solenoid is turned on and off by signals from ECT ECU to control hydraulic pressure affecting lock-up relay valve. Lock-up relay valve controls operation of Torque Converter Clutch (TCC). If ECT ECU detects a malfunction, fail-safe function is enabled. DTC is set when a open or short circuit occurs. Possible causes are:

• Lock-up solenoid open or short circuit.
• Lock-up solenoid malfunction.
• ECT ECU malfunction.