Contemporary torque converters use electro hydraulic control for that lock-up clutch. The hydraulic circuit which locks/unlocks the torque converter clutch is managed using hydraulic valves. The valves are actuated straight or indirectly by solenoids. Visible Inspection:  Begin with a essential Visible inspection. Seek out any indications of leaks or problems https://jasperqcnvc.blogocial.com/torque-converter-clutch-things-to-know-before-you-buy-69745240