Chasing Electrical Gremlins

08 F-450

If I park my truck down hill and it rains, whenever I push the brake pedal, a bell goes off and notification comes up saying “Wiring Fault on Trailer” even when I’m not pulling a trailer. Can last for weeks until I’m assuming the water drains or dries from wherever it’s getting in to.

If I park the truck facing up hill and it rains, I don’t have any issues.

Anybody have any thoughts as to where I should start looking for the source of this issue?

I’m going to start with the plug(s) itself but am wondering if anybody else has had this happen to them.