I just put my 6500# travel trailer onto my permanent camping spot. I did so for the first time with newer 2019 SC Lariat 5.0. 30 miles into the 45 mile journey I get 2 alerts on the instrument panel. They were “Hill Decent Unavailable” and “Traction Control Unavailable”. This also kicked me out of tow/haul mode and rendered drive mode changes inoperative.
I also noticed that the 10 speed tranny seemed to struggle with gear decisions and the engine seemed to be a bit noisy under load. The engine noise seemed to be a change in exhaust note.
Bought this Lariat used with 43k miles on the clock. After 3 years of saving and planning, it was the one I was looking for. Brought it home in December when it was cold in central Illinois. I noticed a lot of quirky technology behavior. Driver preset would not move. Mirrors would not fold when commanded and the auto headlight hi beam was erratic. So these towing alerts have me concerned that maybe I should go back to a less complex XLT.
Has anyone else experienced these types of issues in a Lariat or above?
TIA!

 

Whatever is failing in your Lariat would be the same part in an XL. Hill decent is an FX4 thing, traction control, tow haul mode, and transmission will be the same for all trim levels. Suspect seat presets and mirrors are an add on effect from whatever is truly wrong. Auto headlights are erratic at best and a pretty much useless feature on the 150 on most roads around me. Wife's infinity auto high beams work well.

Not an expert, but it does seem like most (if not all) of your issues are systems that don't function the same sitting still and moving down the road at speed. Would expect a proper expert could find the common denominator.

 

I have a 20 Lariat with he 3.5. I get no issues as you report with my slightly lighter trailer. Others pull much more than you with the 5.0, even if your weight was on the high end (not saying it is), your truck should not have thrown warnings as it did. Good luck, a tough one to track down. The 10 speed, I lock out 8-10 gears, was yours all over the place at speed, mph?

 

The traction control alarm message reminds me of problems I had on my 2008 Explorer. It was caused by an ABS sensor, IIRC. When it happened, most often going uphill, the alarm noise would scare the crap out of you. After talking it through with my mechanic, we decided to live with it. SUV still running strong as a work vehicle for my SIL. I can see it affecting the Hill Decent.
Auto high beam uses ambient light, including other vehicle lights (even reflected light off of signs or fog) and speed to go hi to low to hi beams.

 

My '19 Lariat had a similar issue. There was a TSB on it (see the attached service ticket)