So now your using 2 adapters, 4 to 7 and 7 to 6 and it's still not working. Why am I not surprised. You could have used a 4 to 6, but I'm sure that would not have worked either. Some basic troubleshooting will save you time and money. Slide the cover off the 6 pin trailer connector and look for broken wires and verify they are connected to the correct pins.
Also check the continuity of the 7 to 6 adapter, especially if it's not the same one others are using
I am not surprised it’s not working either. And I am aware I could have used a 4 to 6 but looking online none were available in my area so this was the next best option. Everything is connected fine and all wires are good to go. At this point I’m just assuming the trailer does not like the JLU connection for whatever reason. When I need to use the utility trailer I’ll just use the GMC. Problem solved.
All that have used the utility trailer have used the same 7 to 6 adapter and it’s fine. One thing, they are all GM vehicles so maybe the trailer just dislikes Mopar ??‍
