[DanEC]

I think the trailer relays do heat up as I remember Bob mentioning recently that he might look at Velcro for mounting the relay to the backing plate but he would need to check if the Velcro self-adhesive was heat resistant. I've never touched mine while driving the car. Suspect it heats up when turn signals are activated or brake pedal is held down. It's possible it could be a bad relay - I remember Patrickt saying it is difficult to trouble shoot their circuitry.

Since you have unplugged the brake light switch that would seem to take it out of the equation. What about the turn signals - have you been able to test them with this issue? If the front ones work but the back ones are acting funky that would seem to point in the direction of the trailer relay. I suspect Patrick will be along to help after bit.