Trailer wiring

[AM0608]

Ok so I am hooking up a 7 prong trailer wire up to my 2000 Expedition, it does not have the factory tow package. It has a 4 factory prong wire hooked up I bought a new adapter to fit a 7 prong. When I hook it up and turn on the running lights, the lights on the trailer work fine, as soon as I hit the brakes the lights shut off. If I turn on any blinker both sides flash. Fourways/emergency flashers work as they should. I cleaned the grounds on both the trailer and the Expedition and it's still doing the same thing. I hooked the adapter up to a friend's truck and everything works properly with that truck connected to my trailer. Don't know where to start looking as wiring is not my strongest trait so any help is appreciated. I do have a test light and multi-meter. Thanks in advance for anyone who can help me get this working right.

 

[05expedeb]

On the 2000 model look under the rear and follow the wires from the 4 pin connector they should plug into a larger connector which also is used for the 7 pin wire harness. Send me a PM with your email address and I will send you some information on the connector and wiring.