Trailer Lights Issue - How to Check Location of Short

[TSCTSC]

As you know, I have no running lights on my trailer. I have hazard and turn lights. Apparently, it has been blowing my fuse in the truck. I replace the fuse, and the lights work fine for 5-10 min and then they blow again. GOing to the dealer next week to check the trailer. I have checked the grounds and the external wires on the trailer and they all looked good. How do I make sure that the problem is not anywhere on my truck? Someone in another post mentioned the truck under bed adaptor. How do you check that? Thanks

[Guest]

You have to check every inch of wire on the trialer.. and it could be a bad side marker lamp, etc.. you just never know the source of the short until you find it.

Yes, it is possible its on your truck.. It can also be a lose connection, or just as simple as too much load for the fuse in place for your running lights.

I wish there was a simple answer that would lead you to your problem, but there isnt.

If I cant find the source of the problem eventually.. I just start replacing things until it goes away... needless to say my trailer ended up with new LED tail light this year and new side marker lights.. its a huge difference on current load. Wire is cheap to rewire the entire trailer.. but a pain in the butt to install on most.

Pain.. but no more shorts or blown fuses. Its easiest to replace the vehicle end 1st.

[Surface Tension]

Make sure you have a good ground and your not relying on the hitch and ball contact for ground. I've found its easier to replace the wiring instead of messing around trying to find a short or open.

[Eiger0304]

Surface tension hit the nail on the head. If I cannot figure out a wire problem in less than a 1/2 hour, I just run new wires. Fleet Farm sells the wire by the foot (all 4 wires together). I believe it was $.19 a foot. I also run grounds all the way to the back lights. That way you don't have ground issues especially for trailers that tilt.

As far as finding out if its your truck or not, if was your truck, you would probably blow fuses when a trailer was not hooked up. Have you tried hooking up a different trailer to see if your fuses still blow??

If you figure out it is trailer causing your problems and decide to re-wire your trailer, try wiring up only your taillight/signal lights first. Then if you still have no problems, then hookup your side markers.

[harvey lee]

I have had numerous problems the last 2 years with the wiring and always a different problem.

This spring I bought a new harness and installed it and now,no problems.Well worth the few dollars and time spent messing around all the time.

[burl]

I to had the same problems.Found out some mice had crawled in side of the tubing and ate up alot of the insulation on the wire.Ended up rewire most of the wire from the front back.why do mice like to eat this stuff?Burl.

[VMS]

If you are blowing a fuse inside the truck, it will not be a ground wire issue...it will most likely be a wire that has chaffed against a metal surface and is creating a short. This can get to be a tedious job, but it will require some time and close checking. be sure to have string to tie to the end of the wires so that when you are done checking, you can pull the wire back through (if the wires run through a square or rectangular tube of some sort).

Once you find the Chaffing, cut and soder, then, if possible, find the smallest diameter wire tubing you can find, and run this tubing over the entire length of wire. Once done, you will never have a chaffing problem again.

Not a fun project, but it is do-able..

Steve

[BarryG]

Get someone elses trailer and see if it works or not! If theirs doesn't work it's in your truck. If it works its in your trailer! If it's in your trailer, rewire the whole trailer and be DONE with it! You can buy a complete wire harness at Wally World for $10. That is the easiest thing to do! If I can do it ANYBODY can!

[TSCTSC]

Wow...I need a trailer with has a 5 flat adaptor. IS there an easier way? Is there some tester that I could use?

[BLACKJACK]

TSC, follow the advice you got above and just go get some new wire or a wiring harness thats ready made and rewire. I did my fishhouse this winter, new taillights and all, and it took about an hour - and the only thing I know about electricty is you need it to run your toaster!!

I also like the idea of trying someone elses trailer, it will isolate the problem to your truck or your trailer.