The torque converter clutch solenoid is often energised (trapped on) which interprets in to the torque converter becoming always locked. Slippage consumes power over the coupling stage. Locking the converter shell to your turbine shaft helps prevent this slippage from happening. There are lots of clutches within a torque converter. https://torqueconverterclutch76520.blogsumer.com/33196777/the-best-side-of-torque-converter-clutch