trailer wire, type or connection fault In 2021 Tundra

Good morning. I have that same error message “trailer wire, type or connection fault“ pop up on my brand new 2021 Tundra that I have read many issues on.
Before I had a 2018 tundra and drove all across the country last summer, 6300 miles, pulling my travel trailer and not one issue.
This message appear after driving one hour in a two hour ride a few weeks ago when hooking that same travel trailer to the new Tundra.
My first attempt at Toyota service department, they said, I’ve never heard of this issue and it must be your trailer”. Within these forums, I can see that this issue is not new.
It seems like everybody wants to recommend the P3 aftermarket brake controller and adapter. When researching that, that seems to only work for tundras up till 2019.
Any suggestions on where to begin with a brake controller that is compatible with my 2021?

 

use the search function- upper right. There a A LOT written about the exact subject in multiple threads on this site.

 

SAME WITH MY 2018 TUNDRA STILL WORKING IT

 

My 2020 had the same issue. Turned out the trailers ground was connected to the electric brake wiring.