wire harness for your trailer

skywarn · **Posted:** Tue May 18, 2010 7:31 pm

has anyone had any luck installing an aftermarket 4 flat harness for your trailer with out blowing up the little black box that comes in the harness?? Ive been through 4 u-haul 2 wal-marts and now an e-trailer model that keeps plowing up. called the dealer and they said that i have to buy the mopar harness ($99.30 + shipping) and thats the only way to wire for trailer lights. I went ahead and orderd the part... gues sit was the last one in the USA i called 39 states and 87 part houses and found one in AR.

so the reason i ask, i would love to be able to return this $100 part if ther is another fix for this problem...

so the short question is:

how to wire a 5 wire jeep to a 4 wire trailer?

bueller? bueller? bueller......

TJ2 · **Posted:** Tue May 18, 2010 8:16 pm

I haven't tried to hook a trailer up yet. A flat four works for camp trailers.

The fact sheet on my '05 claims the tow package includes 7 to 4 trailer wiring adapter. Anybody know anything about that?

mag03kj · **Posted:** Tue May 18, 2010 8:28 pm

I wanna say that you can buy a 7to5 way!

dritchie · **Posted:** Tue May 18, 2010 8:43 pm

If you don't have the EVIC, your going to have to get another wiring harness to go all the way up to the dash. I had one adapter go bad, then they put in a heavy duty one and it's been working fine for several years.

Dave

cerich · **Posted:** Tue May 18, 2010 9:11 pm

no evic and a self installed e-trailer 4 with zero issues.

05 Limited

mag03kj · **Posted:** Tue May 18, 2010 9:15 pm

dritchie wrote:

If you don't have the EVIC, your going to have to get another wiring harness to go all the way up to the dash. I had one adapter go bad, then they put in a heavy duty one and it's been working fine for several years.

Dave

Cowcatcher · **Posted:** Tue May 18, 2010 10:54 pm

Hummm....I'm confused. Do you hve a factory hitch and wiring? If you do I am pretty sure it would be 7 wire, mine was. And mine came with the 7 to 4 flat adapter. I have used the adapter several times, as well as an after market one, without problems.

geordi · **Posted:** Wed May 19, 2010 4:04 am

I installed the plug-in adapter kit from (IIRC) E-trailer.com - Plugged directly into both tail lights, in between the magic Mopar plug and the plug on the bulb housing.

No problems at all with the box, the ONLY problem I had was that the "stop light" fuse got cooked by the trailer - lights were too heavy for that crappy little fuse. Replaced with the next size up, no problems since. Flat 4 connector.

TAHOE · **Posted:** Wed May 19, 2010 8:25 am

I've got one of the magic black box adapters that plugs in the harness in the back, made by Hoppy I believe. It has it's own power source that goes to battery, not had any problems as of yet, but then I only hook it to battery when I'm actually going to pull trailer which is very little, use my workhorse 'Hoe for that duty.

ATXKJ · **Posted:** Wed May 19, 2010 8:30 am

FYI - this was the KJCountry writeup on installing the 7 pin wiring necessary for a trailer brake controller.
http://www.jeepkj.com/forum/showthread.php?t=26895&highlight=trailer+hitches

and Retmil's update about making the wiring closer to the FSM
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?p=377369#p377369

LibertyCRD · **Posted:** Wed May 19, 2010 11:37 am

Cowcatcher wrote:

Hummm....I'm confused. Do you hve a factory hitch and wiring? If you do I am pretty sure it would be 7 wire, mine was. And mine came with the 7 to 4 flat adapter. I have used the adapter several times, as well as an after market one, without problems.

x2. Your CRD should have come with everything you need to hook to a standard 4-pin trailer connector. The adapter, if lost, can be bought at Walmart for $10. I use one all the time. It just pops into the 7-pin slot next to the hitch and bingo...

mag03kj · **Posted:** Wed May 19, 2010 11:44 am

TAHOE wrote:

I've got one of the magic black box adapters that plugs in the harness in the back, made by Hoppy I believe. It has it's own power source that goes to battery, not had any problems as of yet, but then I only hook it to battery when I'm actually going to pull trailer which is very little, use my workhorse 'Hoe for that duty.

X2 I got the same one! I use it just about every month!!!

Squeeto · **Posted:** Wed May 19, 2010 2:09 pm

When I bought the truck I plugged in my four wire trailer and it didn't work. I ran it back to the dealer and they said that (in Canada) the truck didn't come stock with a hitch (bullsh?t?) and mine was some after-market job. No warranty.

$10 Walmart replacement has worked since.

mikey1273 · **Posted:** Wed May 19, 2010 5:09 pm

I have the Mopar hitch and only have a 4 wire connector on my Jeep. Its even mounted to a plate... looks OEM too. what would it take to have a 7 wire if I needed it?

jinstall · **Posted:** Wed May 19, 2010 8:56 pm

I remeber that there was a OEM 7 and 4 wire harness for the KJ. I haev the 7 way and it required an extra wire harness that had to be run all the way tot he battery. I also know that the e-spec has a 7 pole and 13 pole system and requires the same harness as in the US. I do not have a EVIC and everything works great, in europe and in th eUS.

boilermaker2 · **Posted:** Fri May 21, 2010 10:20 am

I bought mine new in '05 with Tow Package and Trac-Loc. It came with the 7 pin. Either in the glove box or in the netting on the rhs (shotgun side) in the back was the 7-4 pin converter. This 7to4 flat converter is a little different than some you buy in the store (if I knew how to do picks on this site I'd post, sorry). Anyway, stock adapter works fine but I gave up on the aftermarket one. :2cents:

Oh, also changed out something in the fuse box (forget what its called, that was a long time ago) to run a little more juice to the back EVEN THOUGH IT CAME WITH THE FACTORY TOW.

OK, pulled the manual, note that in the interior fuse box (pag 344 in '05 manual) that cavity 19 is for trailer towing and front fog lights on page 346, in the power distribution center under the hood in cavity F10 there is 30 AMP fuse. I thought there was a relay too but I guess I am confusing it with my old Ram (rest in peace :dead:

)

I thought I was going to be helpful with this post. Now I'm just as confused as the poster.

Cliffnotes: if it is factory tow setup, DCX will have a 7-4 pin that will work. What you buy at the local store may not...

Boilermaker2

Joe Romas · **Posted:** Sat May 22, 2010 7:41 am

ATXKJ gave links to good instructions

I did like Retmil did to make my aftermarket Mopar kits more like factory. The Mopar wiring kit does not, at least mine didn't, come with the 7 to 4 pin adapter plug. However the 7 pin cable and connector follows standard configurations and a proper adapter from Wally's should work fine. The Mopar kits do a good job of isolating the trailer wiring from the jeep's wiring by using relays.

The last thing I would do is take my jeep to U-haul and let them use the clamp on saddle blue splices that pierce the insulation allowing moisture to corrode the wire :furious:

Big Montana · **Posted:** Sat May 22, 2010 2:44 pm

TJ2 wrote:

I haven't tried to hook a trailer up yet. A flat four works for camp trailers.

The fact sheet on my '05 claims the tow package includes 7 to 4 trailer wiring adapter. Anybody know anything about that?

Mine came with one. I keep it in the little net thing in the back of the Jeep. It works like a charm.

dirtmover · **Posted:** Sun May 23, 2010 9:27 am

Squeeto wrote:

When I bought the truck I plugged in my four wire trailer and it didn't work. I ran it back to the dealer and they said that (in Canada) the truck didn't come stock with a hitch (bullsh?t?) and mine was some after-market job. No warranty.

Agreed, this is BS. Mine came factory installed but when I was buying one dealer did try to give me the run around saying that the factory installed was not available here and they would have to do the install.

Squeeto · **Posted:** Sun May 23, 2010 11:44 am

dirtmover wrote:

Squeeto wrote:

When I bought the truck I plugged in my four wire trailer and it didn't work. I ran it back to the dealer and they said that (in Canada) the truck didn't come stock with a hitch (bullsh?t?) and mine was some after-market job. No warranty.

Agreed, this is BS. Mine came factory installed but when I was buying one dealer did try to give me the run around saying that the factory installed was not available here and they would have to do the install.

I think that I was told that all trucks come with the hitch (metal) but you needed to pay extra for the electronics part. Seems counter-productive. Anyway, the junk I pulled out was not oem (I am the second owner) so maybe this is true.

Junk out, new Walmart junk in. No problem.

wire harness for your trailer

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