We have an RV on a 2017 F53 chassis. This has the 3V 6.8 liter V10 with a 5-speed automatic transmission with overdrive.

Our problem is that it downshifts if I touch the brakes going downhill, and if the hill involves corners and slow speeds it will often downshift so low it'll start turning 4500 rpm just coasting downhill. This is NOT in Tow / Haul mode. I've tried driving it with Tow / Haul on and off, and I can't tell the difference in how it drives. It's as if Tow / Haul is on all the time.

I have discovered that when I'm coasting downhill at 45 mph and it's trying to float the valves out of the head (I exaggerate, but I'm frustrated) I can press the Tow / Haul button to turn it on, then turn it back off, and it'll upshift.

My previous RV was on an E450 chassis with the 6.8 liter V10, and it did this in Tow / Haul mode but it drove pretty normally with Tow / Haul off.

I've been told that Ford knows of the problem and has a fix, but I can't find a TSB online. I wondered if anyone else has the problem and has info on it.

I know ... I need to call a dealership, and I will. But I'd hoped to have a TSB in hand when I did.

Thx ... ed