A solenoid is a linear electrical actuator. When is becoming energised (equipped with electric Power) it pushes or pulls a rod that's linked to the hydraulic valve. You will find different types of solenoid used for torque converter clutch control, but the basic principle of Operating is essentially the same. https://torque-converter-clutch53185.madmouseblog.com/14465020/not-known-factual-statements-about-torque-converter-clutch