Fluid Coupling: It will allow the engine to operate independently from the transmission, And so the vehicle can stop without the need of stalling the motor. The torque converter clutch solenoid is often energised (trapped on) which interprets in to the torque converter getting normally locked. A structure function at https://torque-converter-clutch85161.ampblogs.com/5-tips-about-torque-converter-clutch-you-can-use-today-70427447