# trailer lights ?



## bouttimeiv (Aug 5, 2013)

I installed new trailer lights and all work good except when I turn the lights on the car there are no running lights on at the trailer. clueless here any help 
Thanks Mark


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## Captain Ahab (Aug 6, 2013)

Make and model of vehicle will help


Also, what do you mean by running lights? 

Check the fuses to start


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## jethro (Aug 6, 2013)

If the brake and turn sigs work, then it's likely not the lights on the trailer, it's a problem with the harness on your vehicle. Do you have a factory installed tow package or is it an aftermarket harness? If it's aftermarket then there is generally a converter box that often goes bad. On my last vehicle I went through no less than 5 of those plug-in aftermarket harnesses. For the record, they almost always go because the ground wire fails. Once that happens, the controller dies.


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## FerrisBueller (Aug 6, 2013)

jethro said:


> On my last vehicle I went through no less than 5 of those plug-in aftermarket harnesses.



I hear you on that Jethro! I'm on box #4 I believe and I finally got rid of the terrible wiring job the store did and re-wired everything inside my vehicle to reduce the corrosion and weather damage. I also spliced in some fuses between the box and the trailer wiring so we'll see if that helps at all.


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## PSG-1 (Aug 6, 2013)

I had the same problem with the new aluminum trailer I just built. My brakes and turn signals worked fine, but I had no running lights. 

Here's a breakdown of my diagnostic, and how I fixed it. Found a blown fuse in my trucks' electrical center. Replaced it, popped again as soon as I turned on the running lights. So, I knew it was a short to ground. Brand new harness...WTH?

OK, so, next step was to use the continuity meter to check for the short. I put one probe on the ground (white) wire of the 4 pin plug, then touched the other 3, one at a time, and got a beep at each one. Huh? :?: That can't be right! 

OK, let's check a known working trailer harness, so, I checked the trailer for my Triton, got the same thing. WTH? Then it dawned on me, the light bulbs have to be removed to take this reading, as they complete a circuit from hot to ground. D-oh! #-o 

Allright, so, I removed all the bulbs, then started testing. Got no continuity on my turn and stop circuits, but got a continuity reading on the parking lamp wire. I left it connected and jiggled the wires around, to see if something was touching. It continued to beep. So, the next step, I started unbolting a side marker while listening to the continuous beep of the meter. As I removed the stud from the trailer frame, the beep stopped. That's the short! 

When I looked at the back of the marker lamp, I realized where I screwed up. It has little holes where you press the wire in. Well, in addition to having a slot for the positive wire from the brown wire of the harness, it also has a slot for ground. Looking inside the lamp, you can see that one hole comes through and touches the stud, where the other one is not in contact with it. 

Not sure why they do this, unless it's for non-metallic frames that need a seperate ground wire for each lamp. Anyhow, in my haste or inattention, I stuck the wire into the ground slot, which caused a short. Removed it and put it into the correct slot, then checked continuity, no beep. Re-installed the bulbs, and turned on the parking lamps...guess what? Fixed! =D> 

It's possible that it's something like this causing your issue.


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## SumDumGuy (Aug 6, 2013)

depending on how complex your light setup is you are possibly missing a ground. The running lights I have seen typically have a "hot" lead to them spliced from the rear lights cable and then they are grounded to the frame. Check that the frame ground at the runners is good.


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## jethro (Aug 6, 2013)

[url=https://www.tinboats.net/forum/viewtopic.php?p=324961#p324961 said:


> FerrisBueller » 06 Aug 2013, 09:03[/url]"]
> 
> 
> jethro said:
> ...



I just recently got a new truck and happily paid the $600 for the factory tow package for just that reason- which goes against all my principals! After buying a bunch of those aftermarkets I finally got to talk to someone who actually knows what they are talking about and I guess the issue is the ground. With those plug and play converter boxes I guess all the voltage for both lights and all the circuits (turn, running and stop) is grounded through that one ground wire. A factory harness has individual grounds for each circuit. You ever notice that when you pull off one of those boxes that the ground wire is fried, brittle and black? It's just the nature of the beast. All of the other wires are fine, but the ground wire has all the voltage for every circuit running through it.

So I hate to break it to you, but you better just buy a few of those converter boxes and have them on hand! The only thing you can do is periodically reset your ground. Remove it, wire brush it down and remount it. Even then, it's only going to prolong the inevitable.


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## dahut (Aug 7, 2013)

[url=https://www.tinboats.net/forum/viewtopic.php?p=324950#p324950 said:


> jethro » Yesterday, 05:47[/url]"]If the brake and turn sigs work, then it's likely not the lights on the trailer, it's a problem with the harness on your vehicle. Do you have a factory installed tow package or is it an aftermarket harness? If it's aftermarket then there is generally a converter box that often goes bad. On my last vehicle I went through no less than 5 of those plug-in aftermarket harnesses. *For the record, they almost always go because the ground wire fails.* Once that happens, the controller dies.


This is nice to know.
When you say the "ground wire fails," what do you mean? Im assuming you mean the ground connection, but maybe Im missing something?
Thank you.


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## dahut (Aug 7, 2013)

> I just recently got a new truck and happily paid the $600 for the factory tow package for just that reason- which goes against all my principals! After buying a bunch of those aftermarkets I finally got to talk to someone who actually knows what they are talking about and I guess the issue is the ground. With those plug and play converter boxes I guess all the voltage for both lights and all the circuits (turn, running and stop) is grounded through that one ground wire. A factory harness has individual grounds for each circuit. You ever notice that when you pull off one of those boxes that the ground wire is fried, brittle and black? It's just the nature of the beast. All of the other wires are fine, but the ground wire has all the voltage for every circuit running through it.
> 
> So I hate to break it to you, but you better just buy a few of those converter boxes and have them on hand! The only thing you can do is periodically reset your ground. Remove it, wire brush it down and remount it. Even then, it's only going to prolong the inevitable.


Well theres my answer to the ground problem. Thanks.


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