4G & Trailer Brakes Q

Hi all, have a '24 SR5 with the integrated trailer brake controller. Went to pull my cargo trailer this weekend, plugged in the 7pin, truck found the trailer and asked the question on the dash about detecting a trailer, then asked if it was conventional/gooseneck (for which I answered conventional). Lights all work, turn signals, brake lights - all good.

But... when I start to adjust the gain on the trailer brakes before setting out on the road, the truck tells me the trailer brakes aren't available.

So I find the menu for the brake controller, and try to adjust the gain there as well. No luck - same message. Thinking maybe its just a connection issue: shut off the truck, unplug the trailer, start the truck again and drive around until it senses there is no trailer. Shut off the truck again, plug back in the trailer, and start it up - truck finds the trailer, asks the questions again, but once again does not find the trailer brakes.

It could be my trailer - it has sat for a couple of months unused, but I did have it hooked up and moved around with the Taco a few months back, and everything worked then.
I was in a huge hurry, as we were moving this weekend, so I had to just make two trips with the trailer lightly loaded so I could manage without the trailer brakes, but I want to get this sorted for next time I need the trailer. I didn't think to use any electrical cleaner and spray out the contacts on the trailer wiring or the truck wiring, so that will be my first attempt to fix it.

But welcoming any other suggestions, or if any of you have ran into this with towing a trailer with brakes (and the truck not finding the brakes), I'd love to hear if you had to take it to the dealer or solved it yourself? Sometimes, these fancy electronics make life easier and sometimes that make simple things harder...

 

Trace that blue wire from the junction box to the axles/brakes. Possible that some road debris or rat took out the wire.