Torque Converter Clutch Operation

Vehicles With Computer Command Control
The electrical system used to control the activation and deactivation of the TCC on vehicles equipped with computer command control consists of a solenoid and 2-3 clutch pressure switch on 250C or forward clutch pressure switch on 350C located in the auxiliary valve body, a brake release switch, electronic control module, throttle position sensor, vehicle speed sensor and an engine coolant temperature sensor mounted externally of the transmission. The electronic control module receives information from the various sensors and, when vehicle speed is high enough, provides a ground for the TCC solenoid, which activates the converter clutch. When operating conditions such as heavy acceleration indicate that the TCC be disengaged, the electronic control module removes ground from the TCC solenoid and deactivates the system. The brake release switch opens the circuit and deactivates the TCC whenever the brakes are applied to prevent engine stalling.

Vehicles Less Computer Command Control
The electrical system used to control the activation and deactivation of the TCC on vehicles not equipped with computer command control consists of a solenoid, 2-3 clutch pressure switch on 250C or forward clutch pressure switch on 350C and a governor pressure switch located in the auxiliary valve body, a brake release switch, thermal vacuum valve, engine vacuum switch, vacuum delay valve and a ported vacuum source mounted externally of the transmission. The brake release switch opens the circuit and deactivates the converter clutch whenever the brakes are applied to prevent engine stalling. The thermal vacuum valve prevents the TCC from applying until the engine coolant temperature reaches approximately 130°F. The engine vacuum switch releases the TCC when engine vacuum drops to approximately 1.5-3 inches during moderate acceleration, prior to a part throttle or detent downshift. The vacuum delay valve slows the vacuum switch response to vacuum changes and ported vacuum is the source of vacuum to the vacuum switch and opens the switch to release the TCC during a closed throttle coast down.