With the three-passage torque converter, two passages are useful for transmission oil (ATF) stream through the torque converter and for clutch cooling, whilst the 3rd passage is utilised independently to manage the lock and unlock with the clutch. This lack of electric power is often accompanied by increased engine RPMs https://torqueconverterclutch75317.thechapblog.com/33118999/torque-converter-clutch-an-overview