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Unread 02-17-2014, 12:48 PM   #1
thegipper
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rear tail lights go out after towing a boat?

Ok bare with me here, this is an odd one.

My 95 ZJ 4.0 (297k miles) didn't have a trailer hitch when I purchased it. I went to a junk yard and found a factory original one off another ZJ. It has the large round style plug (for the lights) built into the hitch.

After I mounted the hitch I needed to figure out how I was going to hook up the trailer hitch plug on the hitch since my Jeep didn't have a hitch from the factory. When I was at the junk yard I found a few ZJ's that had aftermarket hitches on them and found one that had one of those tail light converter boxes in it, so I snagged it. This is what I used to hook up my 7 pin factory plug.

Ok, so here is where it gets weird.

I've had it setup this way for years now and has always worked fine so long as I'm just towing my small POS boat that just has the two standard brake/trailer lights in the back. I have the little adapter plug that goes from the round 7 pin connection to the flat 4 on the boat.

No issues here, always work perfectly fine.

Last year though I was up north at a friends cabin and we were taking two boats out so I needed to pull one with my jeep. The boat I was pulling was a 17ft alumacraft on a nice aluminum trailer. This trailer has a 7 pin hook up (just like my hitch, so no adapter needed) but also has many more lights including ones on the sides (yellow marker lights) and two sets of lights in the back. I'm assuming it draws quite a few more amps. Anyways, when I hook it up, everything at first works fine but when we were like 3 minutes into the drive my buddy who was behind us noticed that the trailer lights were all off AND all of my tail lights/brake lights on the jeep were off.

We tried screwing with the plug etc, but they wouldn't come back on. After about 20 minutes of sitting the lights (jeep and trailer) started working again only to go back off after a few minutes.

It's like the trailer draws too much juice and causes something to get screwed up on my jeep.

This same boat hooked up to his truck has no issues at all so its not the trailer.

Anyone know what would cause this and how I should go about fixing it. Only reason why I care is because I'll need to pull that boat again come this spring (walleye fishing trip).

Oh btw, the exact same thing happened when I pulled another buddies enclosed snowmobile trailer (rather large) which also had many lights on it. It did the exact same thing, lights went out on the trailer and jeep (rear tail lights/brake lights) until I let it sit for 20 minutes and then it happened all over again as long as the trailer was plugged in. This trailer also had the 7 pin connector.

Any help is appreciated, thanks.

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Unread 02-17-2014, 12:52 PM   #2
Gearhead31
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My first thought is a bad fuse or wire someplace, the extra draw is causing heat which is making it lose the proper electrical contact? Try checking the fuse for them. I think it would be in the side panel up front. If not there, then it would be under the hood. It could also be that since you got a JY one, it's going out? I'll try to dig more and give a better answer later on
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Unread 02-17-2014, 01:17 PM   #3
thegipper
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I'm almost leaning towards it being the tail light converter box that I snagged. What I don't get is why it would cause the lights on my jeep to go out, I could see it "overheating" and making the trailer lights go out but my jeep?

You would think if it was a fuse it would blow and not come back on until the fuse was replaced.

It's soo weird.
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Unread 02-17-2014, 01:28 PM   #4
Gearhead31
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I'm really leaning to a bad box first, then a bad connection somewhere, then a weird short being bottom of the list.. What kind of box did you get, the style that has it's own power wire that goes to the battery or the kind that only splices into the current tail light wiring(either by splicers or by "T" connectors)? If you have the second kind, you need to replace it as you are pulling more draw than the lights are factory fused and rated to.
a brand new basic one that you splice in can be bought at U-Haul stations starting around $35 + tax for a 4-wire blade style. The kind with the "T" connectors are around $45-75 for bladed up to 7 wire.. Both require you to run a wire up to the battery(or other proper power source).
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1995 ZJ ltd, 4.0 i6, *cough stock cough* 253,xxx and still pumping strong
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*In peace, sons bury their fathers. In war, fathers bury their sons. - Herodotus
[QUOTE=JasonStebbins]We can call it the Whoosh King Catalog System. :D[/QUOTE]
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Unread 02-17-2014, 01:41 PM   #5
lionshooter
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Happened to me last week on my 93 ZJ. Hooked up a friend's utility trailer and all lights went out. 5 wire to 4 wire converter supplied by E-Line checked out good. Started tracing wires and got to a little black box bolted into a cavity hidden behind the spare. Inside the box is a computer board apx 4"x4". It had 2 burned contacts. I resoldered it and now the tail lights and blinkers work but still have no brake lights. Don't have any idea where to look next. Fuses all good, pedal switch is good, no shorted wires...mumble, mumble, about ready to unleash the 4 letter words.
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Unread 02-17-2014, 02:05 PM   #6
Gearhead31
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Quote:
Originally Posted by lionshooter View Post
Happened to me last week on my 93 ZJ. Hooked up a friend's utility trailer and all lights went out. 5 wire to 4 wire converter supplied by E-Line checked out good. Started tracing wires and got to a little black box bolted into a cavity hidden behind the spare. Inside the box is a computer board apx 4"x4". It had 2 burned contacts. I resoldered it and now the tail lights and blinkers work but still have no brake lights. Don't have any idea where to look next. Fuses all good, pedal switch is good, no shorted wires...mumble, mumble, about ready to unleash the 4 letter words.
Do you mean a trailer light adapter box or the light outtage module box? the LOM should be a box bolted onto the frame at the rear of that little cubby area, the trailer adapter would probably be towards the front or behind the paneling all together
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1995 ZJ ltd, 4.0 i6, *cough stock cough* 253,xxx and still pumping strong
1998 Chevy Cheyenne K1500, 5.7L Vortec, mostly stock
*In peace, sons bury their fathers. In war, fathers bury their sons. - Herodotus
[QUOTE=JasonStebbins]We can call it the Whoosh King Catalog System. :D[/QUOTE]
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Unread 02-19-2014, 09:16 AM   #7
thegipper
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Update*

So I pulled off my access panel behind the spare to see exactly what I have going on and found these.





One is lamp outage module, the other is the converter.

So here is what I need to know. Is my problem occuring because of something with the LOM or with the tail light converter? Could the converter be shorting because when I'm hooking up these larger trailers with more lights its drawing too many amps? I believe they both have LED lights. I know a lot of those converters have an "integrated circuit protection". Could this be tripping because its drawing too many amps?

As you can see, the converter I'm using doesn't have its own power supply. What I still don't get about this theory is why the tail lights and brakes lights go out on the jeep even if this converter gets "tripped"?

Should I even be using the LOM or should i unplug it and just connect the two connectors together?

Also, I'm using a converter (see the one in the picture) when I have it hooked up to a 7 pin socket. Should I not be using a converter in the first place to hook it up to a 7 pin socket?

I'm not sure where to go from here. Any help is appreciated.
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Unread 02-19-2014, 09:54 AM   #8
jeepjeepster
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Never been a fan of those boxes like that. I like a wiring harness that keeps the trailer lights separate from the jeeps lights.
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Unread 02-19-2014, 10:03 AM   #9
thegipper
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Quote:
Originally Posted by jeepjeepster View Post
Never been a fan of those boxes like that. I like a wiring harness that keeps the trailer lights separate from the jeeps lights.
So maybe I should ditch that converter and get one that has its own power supply. I'm really thinking that is the problem but I thought maybe someone else had some insight.
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Unread 02-19-2014, 01:12 PM   #10
thegipper
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Just got off the phone with an electrical support guy at Draw-tite. Apparently this model of converter is so old they don't have any specs for what it is rated at. I told him my situation and he agreed that it sounded like it was drawing too much power when I was towing these larger trailers and that I should upgrade to a powered converter.

He did say something about I could possibly have a faulty "head light circuit breaker".....Ahhhh......never heard of that before. Anyone know what he's talking about?
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Unread 02-19-2014, 01:23 PM   #11
Gearhead31
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As far as I know, the circuit breakers in our jeeps are not like a house, once they pop, it's like a blown fuse. You need to replace. I do not however have any experience messing with them, that's only what I've read here.
I believe the LOM really only sends info to the VIC to alert you to burnt out/not properly functional light bulbs. I'd imagine you could bypass it but I would rather recommend you don't just for safety sake.
That converter box style is only rated for a 4 wire standard trailer plug, Though I think it could be used to work alongside other input for a 7 wire. Still not sure why it would make all your tail lights go out but since it's related to overdrawn currents, it's not surprising
As to the box issue, definitely get a new box. It's not a self powered unit so chances are it's drawing too much power and somehow not blowing fuses in the process. Since that's the box you have, you can pick up one from U-haul no problem. There's plenty of other places but that's what I have experience dealing with(picked mine up there, $39 w/ tax). There is the kind with the "T" adapters and the kind where you actually splice the wires together. The latter is about $35, give or take for where you are. The prior is another $15. Either way, you will have to run a wire up to the battery or other good power source, any 15a tap IIRC. Give yourself probably half an hr for the job. 45-50 min if you have to end up testing it yourself like I did.

Edit: stupid question, the 7 wire is turns, brake, ground, reverse lights, +12v rail and power brakes, correct? That would mean you need a bigger one for reverse light function. Otherwise you would actually have a 6 pole connector with the +12v and brake booster line hooked up
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1995 ZJ ltd, 4.0 i6, *cough stock cough* 253,xxx and still pumping strong
1998 Chevy Cheyenne K1500, 5.7L Vortec, mostly stock
*In peace, sons bury their fathers. In war, fathers bury their sons. - Herodotus
[QUOTE=JasonStebbins]We can call it the Whoosh King Catalog System. :D[/QUOTE]
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Unread 02-19-2014, 01:30 PM   #12
thegipper
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Yeah I'm probably going to go that route.

I was looking at these on Ebay and they appear to be pretty decent. I got a call into their tech support because it states that it can be used with vehicles that have LED lights but I want to make sure that it will work with trailers that have LED lights.

Anyways, here it is. 10amp, powered, and i can get it shipped for 18 bucks. Anyone have any experience with converters from MME?

http://www.ebay.com/itm/Powered-Tail...d30a91&vxp=mtr
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Unread 03-18-2014, 09:07 PM   #13
thegipper
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Just thought I would update this post.

I installed the powered tail light converter that I found on eBay and it fixed my problem.

Apparently those trailers I was towing were drawing too many amps for a unpowered tail light converter.

Still don't know why it was messing up the lights on my jeep but it doesn't do it any more....oh well

Thanks guys
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Unread 03-19-2014, 10:27 AM   #14
jeepjeepster
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Sounds good, glad its all working now.
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Unread 03-19-2014, 01:55 PM   #15
Gearhead31
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Glad it was the easy fix for ya mate!
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1995 ZJ ltd, 4.0 i6, *cough stock cough* 253,xxx and still pumping strong
1998 Chevy Cheyenne K1500, 5.7L Vortec, mostly stock
*In peace, sons bury their fathers. In war, fathers bury their sons. - Herodotus
[QUOTE=JasonStebbins]We can call it the Whoosh King Catalog System. :D[/QUOTE]
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