Trailer lights only work when headlights off

[NicholasP]

So my trailer lights only work when my headlights are off. I know this topic has been posted a lot here, but my issue is I have my lights on a 2 x 4 mounted on top of my skiff. I thought I had them grounded properly, but I guess not? I have attached a picture to show what I've done. The white wire go to the attachment that plugs into my wire harness on my truck. At no point does it touch the trailer.

Any advice as to what I should do?

Thanks
Nick

 

[bruceb58]

Bad ground.

 

[MH Hawker]

jf you want a chance for help what are you working on

 

[NicholasP]

I'm trying to get the headlights to work on this light bar I have on my skiff. I thought the white wires in the picture had it grounded? they are the same on both sides and then they go to the plug in where it connects to the truck.

 

[Maclin]

What brand and year of vehicle? Are you using the flat 4 wire connector?

What lights are you expecting...
Brake
Signal
Running

Are you sure the other wiring from the lights is headed to the right sockets.
Are you sure the metal bracketing holding the lights is not touching the light wires.

 

[Maclin]

Oops, left out this part...... is the connector on the tow vehicle factory, and did it ever work correctly on any other trailers or applications.

 

[NicholasP]

The vehicle is a 2003 dodge ram 1500. It is a flat 4 wire connector. I'm just trying to get the brake lights to work when I brake and when I signal. Right now, they only work when I have the headlights off. I think the wiring is correct and the metal holding the lights is not touching the light wire anymore than it would be if it was bolted to the trailer. I'm pretty sure this is a ground issue, I just need some assistance in where to ground it as I'm not great with wiring.

 

[bruceb58]

If you know the ground between the lights to the plug is good, look at the vehicle side to make sure it is good.

Reason the brake lights work with the running lights off is that there is a sneak path ground through them. Once you turn the running lights on, the situation is reversed.

 

[NicholasP]

I recently sold my old truck and bought my new (to me) truck. I also replaced the flat 4 plug to make sure there were no issues there. I have had the same issue with both vehicles. So I'm wondering if grounding it to those metal pieces I have holding the lights up is sufficient or is even functioning as a ground.

Thanks
Nick

 

[Maclin]

On my truck with the flat4, somehow the cover had come off and it was getting pummeled I guess, ended up not working any more. I cleaned the contacts but it was a no go. I have the tow package so I use one of these round to flat adapters when I hookup to a flat4...

 

[Silvertip]

I suggest you start at the tow vehicle and see if it requires a unit that allows using conventional trailer wiring with a truck that has SEPARATE stop and turn lamps. Some vehicles use a dual filament stop/turn/running lamp. Many vehicles today do not. You cannot mix the two systems without the converter. I suspect the system on your truck is the type that requires a converter. This is especially important if the wiring on the truck was added by the original owner.

 

[bruceb58]

He reporting that his brake lights won't work with running lights on but works with runnings lights off. That is independent if he needs a convertor or not. Not saying he doesn't but his problem is with something else

 

[Willyclay]

All good advice above but I would start with a Circuit Tester like the one at the iboats.com Store (host of this free forum; hint, hint). See the link below. Good luck!

http://www.iboats.com/EZ-Trouble-Sh...5238237--session_id.772042906--view_id.215416