truck hitch electrical issues, where should i look first?

[DZink24]

i have had some significant problems with my trucks electrical system recently. i have 3 trailers, a utility trailer (no brakes) a boat trailer (no brakes) and a 18' 2 axle flatbed car hauler (w/brakes). when i hook to the boat and utility trailer, i have no lights whatsoever. when i hook up to the car hauler i have brakes and all lights EXCEPT for driver side turn signal/flasher. the running light/headlight on this side does work. when hooked up to another truck, all works as it should. hmm. i am stumped. could it be an issue with the brake controller?? i have no idea. this is all very recent, and very annoying, as it seems like every vehicle i have ever owned has given me grief at some point in regards to trailer lights.

 

[GaryOwen]

Sounds like you may have a bad ground connection at your truck connector. Run a temporary ground from your truck to the trailer and see if that helps. Use a voltmeter or test light on each pin of your truck connector. Wiggle the pins around to see if anything changes while testing.



I have also had bad places in my wiring on my 03. The outer wire cover appeared to be intact, but was corroded inside the wiring.

 

[jelag]

Gary has a good point but I suggest one step more... I'd suggest that the first 2 trailers need to ground through the hitch. . and they sit so much that you just haven't gotten through the rust.....

I'd connect the volt meet or test light to a good ground and test the circuits... and on the ground circuit on the plug I'd go from the 12+ to ground at the plug... .

 

[B.G. Smith]

Are you using an adapter to hook up the boart and utility trailer, if so that could be the problem. I'm guessing the car hauler has the 7 pin plug. If the brake lights on both sides of the trailer work but the turn signal does not then the problem may be in the trailer tow part of the truck electrical. There are some relays and fuses I believe in the PDC for trailer tow. Don't think the trailer brake controller would take out just one turn signal and if the truck signal on that side is working then the multi-function switch is probably ok so back to relays/fuses. bg

 

[wcoomes]

I had a problem where the tailgate lights plugged in, I left it unplugged since taking the tailgate off to load my camper. It eventually corroded and screwed up the entire system.

 

[Mark31]

I had a small amount of spider web in a plug that was hard to find. Triple check ALL your grounds. Don't ever count on a ground through the hitch. Wire in the grounds all the way from the lights to the truck. Lights should all work even if the trailer is not hitched. Take apart your adapter and look for corrode or critter damage. Try a different adapter. The ground in the factory wiring on my old S15 GMC went bad, so I cut the into the harness and grounded the wire to the frame to cure the problem. Unless I have seen visible damage or corrode somewhere, my problems have been grounding problems. Don't feel bad: "Lectricities" have made us all look "dummm" at least once! Mark

 

[Skydiver]

This is where a "Test Light" will pay for itself in 15 minutes.
First place the test light leads on a good, known truck ground and then a non-painted surface of the trailer. If the light glows you have a bad ground.
I love my test light.

 

[PToombs]

Dan, if you can't get it give me a call. I can talk you thru it, or can take a look for ya. I have to babysit the wife this weekend after foot surgery, so I can't run too far, but maybe the next?

 

[DZink24]

what is he consensus here... do i run the risk of blowing a fuse if i run a magnetic temporary light and plug them into the 4 prong that is spliced off the main 7 prong wiring? (assuming the 4 prong has power)