I think RoadRunner is trying to say that the computer would not know if your clutches or bands were worn out. It can only check sensed problems...Torque converter clutch slippage, solenoid problems....Some transmission problems are electrical, some are mechanical. The mechanical ones aren't directly sensed by the computer.
A bad torque converter (IE-Turbine problems, Sprague clutch problems) wouldn't be sensed, but a slipping lock-up clutch would be, as the computer would see the difference in input RPM (Motor RPM) and output RPM (TSS-Transmission Speed sensor). However, the computer wouldn't know if the lock-up clutch slippage is a worn clutch plate or low hydraulic pressure. So the computer doesn't always know what the problem is. (FWIW, Ford Service doesn't always, eerr, maybe rarely, know what the problem is. You kay or may not have a back TC. It is not uncommon to claim a problem, then fix a different problem, but not let you know they were wrong.)
