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    GM Lumina/Grand Prix/Cutlass Supreme/Regal 1988-1996

    Torque Converter Clutch Solenoid



    Most late model vehicles with an automatic transaxle use a Torque Converter Clutch (TCC) system. The ECM controls the torque converter by means of a solenoid mounted in the output drive housing of the transmission. When the vehicle speed reaches a certain point, the ECM sends a signal to the TCC solenoid, (energizing it), and allows the torque converter to mechanically couple the transaxle to the engine. When operating conditions, (according to various sensors), indicate that the transaxle should operate as a normal fluid coupled transaxle, then ECM will de-engergize the solenoid. Depressing the brake pedal will also return the transaxle to normal automatic operation.


    Testing the TCC usually involves the use of special testing equipment. Here is a basic check that can be made to see if the TCC is functioning or not.

    1. Connect a tachometer or special scan tool.
    3. Drive the vehicle until the transmission is warmed up sufficiently.
    5. Accelerate to 50-55 mph (80-88 kph).
    7. Maintaining the throttle, lightly touch the brake pedal and check for release of the TCC. You will know if the torque converter clutch disengaged if the engine rpm increases.
    9. Release the brake, slowly accelerate and check for a reapplication of the TCC. You will know if has engaged by a slight decrease in rpm.


    1. Remove the negative battery cable. Raise and support the vehicle safely.
    3. Drain the transmission fluid into a suitable drain pan. Remove the transmission pan.
    5. Remove the TCC solenoid retaining screws and then remove the electrical connector, solenoid and check ball.
    7. Clean and inspect all parts. Replace defective parts as necessary.

    To install:
    1. Install the check ball, TCC solenoid and electrical connector. Install the solenoid retaining screws and torque them to 10 ft. lbs. (14 Nm).
    3. Install the transmission pan with a new gasket and torque the pan retaining bolts to 10 ft. lbs. (14 Nm).
    5. Lower the vehicle and refill the transmission with the proper amount of the automatic transmission fluid.

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