Cargo Lights on New Enclosed Trailer Blow Fuse

Updated 04/25/2020 | Published 04/23/2020

Question:

I have an enclosed 30’ trailer that’s about 9 months old. Recently I can’t seem to get the cargo lights working. I have break lights and blinkers. I’ve replaced to fuse in my pick up twice now, the lights come one for a second before the fuse blows. I have a 2019 GMC Sierra and a 2019 hallmark trailer. Any advice on next steps to solve this issue

asked by: Ulises G

Expert Reply:

If the fuse only blows after you turn the lights on, then I'd be willing to bet that there is a short on one of the wires somewhere between the switch and the lights. Unfortunately the only way to check this is to trace all of the wires for the lights looking for any sections that are damaged, frayed, or pinched that could be touching a metal part of the trailer.

When I see this on newer trailers, it is often times due to the wires rubbing against a sharp metal edge of the sub-frame that wears through the wire insulation. The trailer may be too new for this, but I'd also check for corrosion on the light switch terminals.

Let's start there and let me know if you don't find anything. If you don't, I'd be curious to know if the fuse blows any other time such as when you hook up the trailer or if you just jiggle the light wires. Could you also tell me which fuse is blowing in your truck? Is it the 12 volt battery charge fuse? It is a shame to have this problem with a new truck and trailer, but we'll figure it out.

expert reply by: John H