F$#&@@# Trailer lights ?

[SmokinM]

It's always something with them.

My stock trailer has got an issue going on between the parking lights and the electric brakes. When you turn on the park lights it causes the connected indicator light to go out on brake box and energizes the brakes. Turn them off and push button on brake box and the running lights come on. The brakes work as normal if the park lights are off if that helps.

First thought I must have a short in park lights but can't find anything there and it won't blow the fuse. Then I thought maybe a wire rubbing. Can't find any places any where that that's the issue and I got to say it is nicely wired all factory harnesses with heavy insulation. Now I am thinking it is a ground issue and one is back feeding the other. Is it more likely the park lights or the brakes if that is the case? Any other thoughts? Electrical issues are the worst!! Thanks for any help!

 

[SBMF 2015]

Check the doing in the trailer plug. We have had issues in the past with the spades in the plug loosing up and electricity jumping.

I would disconnect the brakes.

 

[Rydero]

Definitely take the plug apart and look for wires that aren't very secured or stripped too far back so they can touch each other. Sometimes the trailer has a junction box and problem could be there too but probably the plug itself. Somewhere the brakes and lights are connected. Indicator light turning off on controller is a clue. Brake controller sends voltage back and when it sees a ground it knows the brakes are there. It can't detect the ground because it's seeing voltage from the light circuit instead which it would expect if nothing was hooked up.

 

[Nesikep]

do you have a second trailer to be able to tell if the probelm is on the truck side or trailer side?

it does sound like a short between the running light and brake light circuit, connector plug is a prime suspect, is there a junction box somewhere?

On my cheaparse trailer they had the wiring running in a conduit pipe, and the brainless morons put the pipe where the suspension squashed it to bits and shorted everything out.. take a look around and look for damage somewhere... Dog/cow chew on the wiring??

 

[SmokinM]

Replaced the plug already that was my first thought also. Definitely on the trailer side as all my others do fine and both trucks do the same thing on this particular trailer. The fact that it will back light the parking lights off the brake box has me thinking a ground issue just can't find it. I feel like if the parking brake circuit was grounding it would be blowing a fuse.

 

[FungusProudKY31]

If the ground on the trailer is attached to the frame with a rivet I'd drill out the rivet and replace it with a small steel bolt and nut. That cured a problem for us one time on dissimilar metals from an aluminum rivet.

 

[Chevy]

I like the title! We have some them trailer lights and a truck head light must be the same brand. Lmao that's good. F$#&@@#!

 

[SmokinM]

Think I found it. Somewhere along the lines the previous owner had backed it up over something and pinched one of the factory pigtails in the skid pan at the back where they shield them for loading docks. It has a ground, brakes and park light wire in it and they had holes in them about the size of a pencil lead. Of course that pan and every other wire shield on the trailer is riveted in from the factory.

The nice thing is the way it is done with different wire harnesses linked together I could unplug them one by one and isolate out down to which section it was in using a test light and my daughter as a spotter/ button pusher on brake box. Otherwise I may never have found it. Thanks for all the ideas and feed back.

 

[Nesikep]

Think I found it. Somewhere along the lines the previous owner had backed it up over something and pinched one of the factory pigtails in the skid pan at the back where they shield them for loading docks. It has a ground, brakes and park light wire in it and they had holes in them about the size of a pencil lead. Of course that pan and every other wire shield on the trailer is riveted in from the factory.

The nice thing is the way it is done with different wire harnesses linked together I could unplug them one by one and isolate out down to which section it was in using a test light and my daughter as a spotter/ button pusher on brake box. Otherwise I may never have found it. Thanks for all the ideas and feed back.

So I was kinda right!

 

[cfpinz]

Stuff like that will drive you plumb mad!

So now that you've got that all straightened out, are you ready to tackle that fancy '99 feed truck that I bought for the wife?

 

[SmokinM]

Ha ha! If you cant figure it out I know darn well I can't but I will be glad to come up there and lean over the hood and drink beer anytime you need moral support!

 

[SmokinM]

Yes you were Nesi.

 

[Caustic Burno]

Converted to 7 pin RV plug yet?
Makes lots of problems go away.
I converted everything last year.

 

[Lucky]

Trailer wiring is always a PIA and it never fails that you don't have any help around to sit in the truck. I bought a Power Probe last year when I was fighting a similar issue, it helped but I'm not smart enough to use it correctly.

 

[cfpinz]

Converted to 7 pin RV plug yet?
Makes lots of problems go away.
I converted everything last year.

Different strokes for different folks. The first thing I do whenever I buy a trailer is cut those darn things off and put an old 6 way metal plug on.