After changing the transmission fluid and filters sets po762 after driving 10 ft

Yes. It was giving po708 so I removed the pan to inspect the internal harness and range sensor. I did not unhook any of the solenoids, changed filter and added new fluid. I just went over and made sure the harness plug was tight, and the TCM plug. Still gave code after coasting for a few feet. I don't think the fluid has ever been changed in over 100,000 miles.