Fashionable torque converters use electro hydraulic Manage for the lock-up clutch. The hydraulic circuit which locks/unlocks the torque converter clutch is managed working with hydraulic valves. The valves are actuated right or indirectly by solenoids. The control of the oil tension in the lock-up clutch is done by two valves: https://torque-converter-clutch75296.ziblogs.com/34089271/torque-converter-clutch-things-to-know-before-you-buy