1997 Toyota Paseo • 157,000 miles

I have a 770 code and would like to know if the Trans solenoid is something I could do. I will have to replace the axle bearing on the driver side due to the slop.
December 22, 2012.


Circuit Description

ECT ECU uses signals from vehicle 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: l Lock-up solenoid is stuck open or closed.
L Valve body clogged or valve stuck.
L TCC malfunction.

Diagnosis & Repair Procedure

Remove and inspect operation of solenoid. If solenoid is okay, inspect valve body.


1. Access ECT ECU. Ensure ignition is off. Disconnect ECT ECU harness connector. Using ohmmeter, measure resistance between SL, S1
and S2 terminal and ground for appropriate solenoid.

2. Replace solenoid if resistance is not 11-15 ohms. To check solenoid operation, apply battery voltage to SL, S1 or S2 terminal of ECT ECU connector for appropriate solenoid. Ensure operating sound can be heard when battery voltage is connected. Replace solenoid if operating sound cannot be heard.

3. To check solenoid seals, remove suspect solenoid. Connect battery voltage to solenoid. Apply 71 psi (5 kg/cm2 ) of compressed air to solenoid with battery voltage connected. See Fig. 10.

4. With battery voltage applied, air should pass through No. 1 and 2 solenoids. Disconnect voltage to solenoid. Ensure air does not pass through solenoid. Replace solenoid if defective.

5. With battery voltage applied, air should not pass through lock-up solenoid. Disconnect voltage to solenoid. Ensure air passes through solenoid. Replace solenoid if defective.

Dec 23, 2012.