Trailer Tow Lights Fuse Keeps Blowing

[TomAce]

Hello,
New to posting here, but have found a lot of useful info on here...

Anyway, I have a 2017 RAM 2500 (6.4L). Just hooked up my travel trailer, and towed it for the first time at night. The running lights on the trailer last about 5-10 minutes, and then the truck fuse blows. I thought it may have been just a bad fuse, so I replaced with a new one. Started down the road, and 10 minutes in, it blew again.

It's not the trailer because I then hooked it up to my Yukon, and the running lights on the trailer work fine, and STAY ON with no fuses blowing in the Yukon.

Any thoughts on this?

Thanks!!

 

[PolarisCobra]

Did you drive the Yukon with the trailer connected? I have seen mice get into the wiring, eating the insulation. When you drive, and hit a bump or a curve, the wiring in the trailer moves a bit, the bare part shorts to the frame, blowing the fuse. When stopped, if the bare spot isn't touching the frame, the fuse will hold.

Mice are the worst...

 

[TomAce]

Did you drive the Yukon with the trailer connected? I have seen mice get into the wiring, eating the insulation. When you drive, and hit a bump or a curve, the wiring in the trailer moves a bit, the bare part shorts to the frame, blowing the fuse. When stopped, if the bare spot isn't touching the frame, the fuse will hold.

Mice are the worst...

Yes, I drove around with the trailer connected to the Yukon. Went for about a 20-minute drive, drove on city streets, pulled into a parking lot, drove on some gravel and uneven roads with pot holes...lights stayed on.

 

[turkeybird56]

Could be a short at the hitch receiver where U plug into trailer to 7 point connector, something grounding improperly, but just a thought.

 

[PolarisCobra]

Yes, I drove around with the trailer connected to the Yukon. Went for about a 20-minute drive, drove on city streets, pulled into a parking lot, drove on some gravel and uneven roads with pot holes...lights stayed on.

Well - It was a good theory at least. I am still betting that something is sorting to ground from the trailer connector back, keep us posted.

 

[TomAce]

I still have not figured it out. I've taken the truck to the dealership, and of course they did their "test", and everything is "working". The problem with their test is that they probably just did some circuit testing while the truck is in the shop, stationary. I had told them if the truck is not moving, everything works. Their response is "well, then it must be your trailer. I respond with "Well, I disagree because when I hook my Yukon up to the trailer and do a road test, nothing blows, and everything works properly."

I feel like this will never get resolved because shops are lazy as hell, and all the blame goes elsewhere. Why can't someone just want to try and troubleshoot the problem? So frustrating!

 

[Badger 13]

My thoughts are pretty much what others have said, some type of short in the plug at the back of the truck, or maybe where it plugs into the harness on the back side of the bumper. Any chance of picking up that connector harness at a junk yard, or maybe get the Curt harness that T's in under the truck and give that a try ? That would by-pass the factory plug. Another idea is, just to pick up another trailer end plug and drive around with that in for a few days and see if blows the fuse. I can feel your frustration. Hopefully you can get to the root of the problem.
Good luck with it.

 

[TomAce]

get the Curt harness that T's in under the truck

Badger, Not sure I'm following this comment. Can you please explain?

 

[Badger 13]

Tomace, from the sounds of your problem it is on the truck end. To help troubleshoot, I always did it in "segments", not knowing exactly where the problem is. By using an replacement 7 pin plug with nothing attached to it might determine if there is a short right in the truck connector itself. From there you could continue on by pulling the wiring harness apart behind the bumper and check for shorts there. Curt makes a "T" harness that can plug into the harness behind the bumper. People use that for wiring in the under tailgate light bars, or to use a 7 pin plug in the box to use with 5th wheel trailers. With this type of testing you will be able to see if the problem is at the back of the truck, or if have to start trouble shooing further forward. Hopefully this makes sense. Also, just throwing this out there, was the trailer wired for the Yukon, or did someone at one time maybe mess with the trailer wires ? The only reason I mention this, I have seen where someone wired a trailer to a vehicle but it was not the "standard" trailer wiring..

 

[TomAce]

UPDATE:
So I was at Lowes the other day doing some shopping for other things, and happened to go up the aisle that had towing "stuff". They had one of the T harnesses that Badger13 suggested, so I bought it. Took it back home and hooked it up...positioned it so that it was just under the bumper and not hard to get to.

Just took a trip with the trailer to Angel Fire, NM. And guess what...NO ISSUES WITH THE LIGHTS.

Now, if I can get the dealer to replace the factory harness...

Thanks for the suggestion Badger!

 

[Badger 13]

Nice to hear that you tracked down the problem, and hopefully the dealer will replace the factory harness. Issues like these are such a pain, but fortunately some of us run into these issues and find a fix. You also picked a beautiful part of NM for take a trip to as well.