The torque converter clutch comes into action to mitigate the inherent inefficiency of the fluid coupling at bigger speeds. The TP sensor indicates the throttle plate angle. If the motive force accelerates to vast-open throttle, the TCM disengages the TCC to downshift. In torque converter no shifting system is necessary https://rylanekmlk.blogocial.com/torque-converter-clutch-secrets-69997227