Hello,

I'm hoping someone can point me in the right direction. The KJ was wired for 7-pin trailer lighting with the MOPAR wiring harness. It was done before I got it. Anyway, the running lights on the trailer quit working. Turn signals and brake lights work, but no running lights. After tearing apart and testing things several times, I have reached the conclusion that power is not being sent from somewhere in the front of the vehicle to the harness in the back, i.e. the MOPAR trailer harness is fine. All the fuses are fine, unless there are others besides the ones by the battery and the ones by the drivers' door.

In this pic, you can see a wire bundle going up over the right rear wheel well. This contains the black and red wire that is supposed to power the trailer running lights. So my question is: does anyone know where these wires go? They seem to disappear into the oblivion behind the dash.


This is the back of that plug, where you can see the black and red wire going into the upper left corner of the plug. Note, this is not part of the MOPAR trailer harness, it's part of the vehicle. Wires come into it from two different directions; most from the left side of the vehicle, and a few from that bundle in the previous pic.


This picture shows the MOPAR trailer relay bundle. The one second from the bottom is the running light relay. Power is supposed to come in through that black and red wire, then when the relay is tripped, flow out through the black and lime wire just above it, out to the trailer. Continuity testing has shown that the relay is working, there's just no juice to pass along. If I can't trace the black and red wire, would it be ok to tap into the wire that trips the relay to power the trailer lights? Because that still works. But I don't wanna make things worse.


Sorry if the pictures are huge. A big pre-emptive "Thanks" for any ideas!

Just working from memory here, the stuff that comes from the left, is parking light, brake light and one of the turn signals, the stuff from the right is just the right turn signal

Check the ground wire or consider simulating a ground wire to supplement/replace the ground wire

most trailers get their ground from the hitch ball contact

if your vehicle lights are working correctly, the place I would start would be trailer grounding

the power leads that feed the functions of the trailer lighting are tied right in with the rest of the vehicle light function wiring somewhere in the dash/underbody wiring

you sure the exhaust didn't burn the harness or rub the parking light feed? for some reason im thinking it was a brown/yellow wire for parking lights in the trailer harness

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03 Renegade (Black)
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Thanks for looking at this. I suppose I should make a few clarifications:

--All vehicle lights work as they're supposed to, and I definitely don't want to change that!

--All lights on the trailer itself, and the mopar Y-harness (that includes the relay pack) all work as they are supposed to, provided they are given power as intended of course. As in, nothing in the rear of the vehicle is broken (I was hoping that's where the problem was).

The problem is that there is a wire from the front that powers the trailer tail lights (as in parking/running/use-when-it's-dark-out lights), separate from the vehicle tail lights, and it is no longer supplying power. I don't know where to look for the source, and I'm not gonna try to take the dashboard apart.

Truth be told, I don't fully understand all the wiring here. It is FAR more complicated than what I've seen done on other cars, where you just splice into the vehicle tail lights for trailer lights. I *think* what they are doing is tapping the power for the vehicle tail lights to actuate relays that transfer power from a separate source to the trailer. That way, if something goes screwy or shorts out on your trailer, it doesn't take the vehicle lights out with it. But I'm not clear on why I'm getting power for the other functions, like turn signals, brake lights, etc but not for running lights. I mean, I know it's because it comes from someplace else, but where and why? Wouldn't there be a fuse for that somewhere? I see in the book there is one for "Frt Fog Lights/Trailer Tow Stop and Turn Lights" and it is good, and all those functions work. There is nothing about trailer parking lights or tail lamps, though, and that is the circuit that has stopped working.

Thanks again!

I beleive mine had an inline fuse with it and the power connected directly tot he battery. The blue os for the trailer brake modual and the rest I forget. I am not sure where my wiring diagram is. If you look at the Just for Jeeps website for th e7 pin you can download and print the install manual and go from there.

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No longer a CRD or Jeep owner. Selling everything I have, needs to go as I need the room for a project.

Thanks jinstall! That manual for the front harness is one I'd never seen before, didn't know it existed, and it might just be exactly what I needed.

I love this board.

Thanks again, and Happy Easter!

Just wanted to conclude this little episode, in case anybody else has the same thing happen. Jinstall was right, there is another wiring harness that goes up through the front, that has its very own fuse. I replaced it, and now all is well again. It's just one of those cases where if you know what you're looking for and where it is super easy to fix, but if you don't, you might never find it. Here's a picture of the rubber fuse case, it was right next to the battery all along. D'oh!



Thanks again, everybody!

My aftermarket one plugs in just like in the pix!

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GONE-2003 Liberty Freedom Edition-GONE

2011 LTZ CrewCab Z71 4x4 Silverado.
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