I posed a question several months ago about my 2015 F-150, and never seemed to get any replies. So this might be a good start to seek some help, not to steal the thunder from OP.
My issue is regardless of what the gain is set to, the "output" to the trailer, is never more than 1 bar (Occasionally when I am stopped, and I press the pedal hard I can get a second bar to illuminate).
So the problem is, when I am trying to slow down, particularly if I am going down a hill, the truck will shift down dramatically. For example, I was going 45 mph toward a traffic signal, down hill (not steep, but it was down), and the truck went from 5th gear to 2nd gear. It is alarming when the truck drops to 2nd at that speed, and the rpm jumps up. Not to mention it is a little embarrassing when the engine is screaming down the hill.
Additionally, I have reached the point where every time I have to slow/stop I have to use the lever on the controller. If I don't, the truck down shifts and I go through the same thing. What is the point if I have to manually apply the trailer brakes with the lever, every single time? If I'm slowing to make a turn, I would kind of like to have 2 hands available to work the steering wheel and turn signal and all of that.
I never had anything like that happen in my 2013 F-150. It never down shifted, and I never had to apply the brakes with the lever. Same trailer, only difference is with the truck. We traded trucks mid season, so it wasn't a situation where it worked with the '13, and then over the winter we made the trade, and then it "didn't work" with the '15. The change from "working" to "not working" happened over a period of about 3 weeks mid season.
My personal opinion, and I am not a mechanic in any way, is that the truck is sensing the trailer brakes are not being applied (or atleast not applied enough, which goes back to my previous statement about the "output" lights not being more than 1 and occasionally 2 out, if I remember correctly, 6), and it over compensates with engine brake by down shifting. As I said, it is startling when it dramatically downshifts. It has even down shifted to 1st from 4th. I am under the impression down shifting to first is never a good thing. I remember when I drove a manual transmission, the only time I put it in first was if I was standing still.
Apologies for hijacking this thread, just curious if anyone has any suggestions. I will be having the trailer brakes and the wheel bearings serviced in the next month or so, so any suggestions are appreciated
2015 Rockwood Mini Lite 2504S
2015 Ford F150 Ecoboost