The TP sensor indicates the throttle plate angle. If the driver accelerates to huge-open throttle, the TCM disengages the TCC to downshift. There are lots of means of locking the torque converter clutch. These variations are purpose of the hydraulic circuit controlling the clutch actuation. You may see inside the https://beckettvwtro.jts-blog.com/32968950/new-step-by-step-map-for-torque-converter-clutch