I have a 2017 Explorer Limited V6 (no turbo, no ecoboost) with about 71,100 miles on it that is experiencing a hard shift between 1st and 2nd gear almost every time. It happens most times at low speeds, rolling speeds, and first time out of a parking space or driveway. It also happens at times when quick surge of acceleration is needed; for example, a slow roll through intersection and then need to speed up quickly. It started around June of 2019 (50,000 miles) and I brought to the dealer. They did experience it, but said without any codes or errors showing they would just be guessing and didn't want to recommend any fixes.
The frequency has increased and it happens now almost every time after initial startup and in all weather conditions. Now (April 2021) I brought it back to the same dealer to see if they could check the transmission fluid levels and test drive it again and this time they told me I need a new transmission. No codes are showing still but this time they say they diagnosed it and "its something inside the transmission". I also took it to a second dealer for them to diagnose it and they tell me they cannot determine what is causing the problem and replacing the transmission may or may not fix it.
Also worth noting: I park in a driveway with slight incline, front end up (maybe 3 to 4 degrees) and after I back out of the drive way I drive down a long gradual hill until I reach a stop sign. The first hard shift always happens at that stop sign. I try letting the car sit idle for about 30 seconds before starting out to let it remember the shift points but that doesn't seem to help. I've also followed instructions to remove power and reset the shift points. This seemed to help at first but eventually the hard shift returns. I bought the car used and it was a fleet vehicle before me. But this issue did not happen immediately.
Is there any way I can be sure that replacing the transmission is the right way to fix this?
