I just bought a new Haulmark 28ft Egde enclosed trailer. All lights work except my dome lights. I checked my plug on my truck and I thought there should be one that is always hot. These dome lights are 12 volt. Help!!

 

The interior lights on my (Well Cargo) trailer only work when at least the parking lights are on.

Are you using a 4-way flat connector?

 

They are most likely hooked up to the battery charge wire on the truck. The truck has to be running for that wire to receive 12V. Try using them with the truck running.

 

You guys hit it on the head. My ignition has to be on for the dome lights to work. Thanks guys.

 

Ignition? Really?

Well...wait are you using a 4-way flat or a 7-pin? Probably a 7-pin, right? You must have brakes on a 28' trailer.

 

Yes, I am using the seven pin that came with the truck and my understanding is on any car hauling trailers use must have brakes on it.

 

I have the same problem, my truck is a 04 f350, my trailer is a 99 Halmark. I have not tired the trailer dome lights with the truck running, but I believe everything is wired correctly on the truck. The trailer lights work properly on my Dodge. I use my trailer in part for camping and would like to have the dome lights work with the key off and in my pocket! This is my only trailer and I am the only user I can take the risk of wiring this to be always hot. What changes need to be made to the truck to make this + termnal always hot even with the key off?

Thanks for any help.
JOE