93' XLT Factory Trailer Wiring Not Working!

[DGrant09]

Does anyone have experience with the factory trailer wiring in a 93' XLT? I have tried several times to get this working and come trailer pulling day I find a light or all lights not working, which is the case today, the wiring harness we bought that runs from the round connector behind the left rear bumper to the trailer is new and continuity (truck is a 7 pin, trailer connector is 4 pin).
I have looked for diagrams and trouble shooting guides with no luck.
I would deeply appreciate any trouble shooting info.. We have a 5,500 mile trip this summer and we'll be pulling trailers the whole way..
The trailer lights are also good, each time this happpens I end up using our Durango to pull the trailer..
Thanks in advance!!

 

[ExploderHOKIE]

First things first, get a test light and make sure you have power at the 4 prong connector, if you do, you've got a trailor problem, but if you don't then disconnect the 4 prong wiring from the plug under the rear bumper, and test that connector, you might find out find you have a simple problem like a bad ground or connector

 

[DGrant09]

Thanx, but I ran those tests to the connector under the bumper with no luck. What I did last night was buy the wiring adapter for an Explorer without the factory tow package (our's has the package and a different adapter) and installed that along with a heavy duty flasher unit. The Explorer FINALLY "legally" towed a trailer last night!! This was frustrating getting to this point for I spent a good bit of $$ on shocks, tires, and serviced the truck to pull a trailer and something simple would always creep in on tow day and stop the show..