I have a 2011 F150 with the 3.5 Eco Boost engine. Mileage is 136,000 and transmission fluid changed at 130,000. While driving on the highway at 65 mph using cruise there are no problems while on level ground or going uphill. When going downhill on a moderate grade the transmission will shift down to forth gear making a loud shifting noise. Depressing the accellerator the transmission will shift back to sixth gear. The does not happen when not using the cruise control. Any thoughts or reasons

 

The cruise does have some software with it that down-shifts my truck too; however only when my speed downhill exceeds the set-point by quite a bit (like 5 mph); it happens more when towing of course; but this upshift has happened without my trailer and therefore not in tow/haul mode, but using the cruise. It has always seemd warrantd when my truck has done this; moreover the shifts are smooth. Perhaps there is a problem with one of the sensors that helps control this. I know our trucks have a vehicle angle sensor; that's how the hill-assist (which works awesome when retrieving my boat at the ramp) works. There are likely several sensors the computer uses to do a myriad of tasks. Just a thought!