U-Haul 4-flat harness in my Jeep doesn't work

[TomOfTarsus]

Hi y'all!

I have gone through the purgatorial suffering of chasing all the gremlins out of my trailer wiring. It's a simple, no-brakes trailer with a 4-wire configuration. About a year ago, I had the local U-Haul outfit wire in a connector so I could pull the thing behind my Jeep, a 1999 Grand Cherokee 4wd, 4.0L straight six model.

I have no power on said harness. BTW, before starting this thread I've searched here and on the Jeeps unlimited forum, where I've also posted and asked for help. On that forum, someone said that the U-Haul harness is not simply a matter of hooking into the tail light/brake light/turn signal circuits, say, right at the light assemblies; instead, there is some kind of a box that may have burned out, particularly if I had a short in my trailer wiring, which does seem to be the case (tail light - brown- shorted to ground). That thread has gone nowhere, but it said before I revived it that this box was cheap to buy and relatively easy to replace.

Since it is a royal pain for me to get the thing to the U-Haul dealer, I was wondering if anyone here might know where the box might be and how to get it, and then where to buy the new one?

Thanks, I sure appreciate it. Keep your wheels down and your ROPS up!

Tom

 

[tommu56]

What kind of lights do you have on the rear of the jeep ?
If it has the amber turn signals you will need the converter.

I usually putt them in behind one of the taillights and run one wire over to get the other turn signal.

as for the 4 wire flat plug
white is ground
yeLlow is left turn and brake
gReen is right turn and brake
brown is the parking lights

here is a link on the wiring
http://65.196.229.68/fitguides/pdf/N119176.pdf

and a link to buy one

Amazon.com: Curt Manufacturing I-24 Tail Light Converter 3 To 2 Wire: Automotive

and this link says they have to be powered I'm not sure about it

http://www.truckstuffusa.com/poweredtaillightconvertertrailerwiringkitsbyvalley.html

tom

 

[TomOfTarsus]

Thank you, and yes, I have the amber turn signals on the back of the Jeep. I have the trailer wiring down & problems corrected. But that U-Haul wiring harness in the back of the Jeep has no power at all.

The plug has both the traditional 4 wire flat plug as well as a plug for a U-Haul trailer (2 white, 2 black, 4 female sockets) and LED's on the U-Haul plug side that don't light.

I suspect I've burned this mythical box out somehow. I'll check your links, thanks again.

Tom

 

[firemanpat2910]

U-Haul 4-Way Flat Piggyback Plug
60" Lead
U-Haul 4-way Flat (tow vehicle side) wiring with the U-Haul patented piggyback feature. Allows for hookup to trailers with 4-way flat wiring as well as classic bullet connections.
Price: $8.50 ........................ If that is what you have the picture shows crimp on connectors. 99% of all trailer light issues are with the ground (white wire) 99% of other problems are with those crappy crimp connectors. test #1 does trailer work on any other vehicle? test 2 does it make the lights work when you hook to the ball(2nd ground-not reliable) test 3-ohm meter from white truck end of plug to ground?

 

[firemanpat2910]

test 4- volt meter or test light from GOOD ground to brown truck side wire parking lights on should be solid 12vdc test 5 leave ground connected turn on 4ways, should have 12-0-12-0-12-0 vdc on yellow and green wires. I would bet a beer its got to do with the connectors and the ground.... But some times there areseperate fuses under the hood for trailer wires, just because the taillights on jeep work that dose not rule out simple blown fuses. to edit..... test 3 should have as close to 0 ohms as possible high resistance means bad connection=means bad ground

 

[Diamondpilot]

The last one I installed on a Cherokee I needed to access the drives side rear wheel well area. You can do this by removing the interior trim panel from the cargo area and you should see the box and wiring. Check all connections and if nothing looks suspect just change it out. You can get them at WalMart or any auto parts store for about $12. Its called a tail light converter. Basically it converts a 5 wire system to 4.

Chris

 

[TomOfTarsus]

Thanks, all, I'll check it out tonight!

Tom

 

[radioman]

This reminds me of a freind I did as well. They were getting ready to go to maryland with thier jeep and lights wasnt working. Found the trailer wiring was shorting out through the conduit pipe and it burned out the convertor box that was hidden in the wheelwell like diamond piolt did. Since uhaul did thiers too, we had to look for a uhaul type of convertor box so I didnt have to rewire anything. It was a simple plug in thing.