01 379 electrical problem

I'll try to make this make sense. Last night I discovered an issue on accident. I've had a jumper wire between the brown and black wires on the trailer plug for sometime. (Pulling a bullrack occasionally when I turned the inside lights on it would trip the breaker, putting a jumper between the brown and black would help with this. Last night doing some work I had the trailer cord unplugged from the truck and turned the clearance lights on I only had half my normal clearance lights and if I had the headlight switch turned on it defaults to high beams only(something peterbilt does when something isn't right. Plug the trailer cord back in and everything goes back to normal (the jumper wire between brown and black is used when cord is plugged in.

So basically I don't have power on the black wire only on brown at the trailer cord and only half my marker/clearance lights on the truck work and it causes some strange problem with headlights too. If I jump brown and black at trailer plug everything works fine.

I'm stumped. Ive checked everything in the fuse panel and clearance and marker lights don't have a different designation anyway. Help me if any of this makes sense to anyone.
I hope I was clear as mud. This is without a trailer hooked up.

 

I wish I could get to the back side of the fuse panel to poke around a little better with the test light. I've had issue with connection in there before

 

That sounds like it could certainly be the problem as well. I hate these electrical problems so much

 

Turns out it was a relay that wasn't getting good connection. Don't know why I didn't check it better Friday night I've had trouble with this one before.

 

It was a frustrating weekend. Going to start pulling a different type trailer so I was installing a wet kit this weekend (60gpm hyd pump) .Not cheap. Pulled the bottom cover off transmission and feel around a little bit. Definitely have a bearing going bad, way to much slop and silver in the oil. But filled it with fresh oil, hope to get a little more time out of it. Oh the joys of an older truck . just overhauled engine this winter and I have a rear end gpnng need work soon to.

 

Yeah I know. Where's that banging head against the wall emoji.​