Trailer Wiring Problem on 1994 Ford Explorer Eddie Bauer Edition

My explorer came with the towing package, On the left rear side behind the bumper i have the little round plug with 8 Wires. There is a dust cap covering that one, and it runs up and hooks into the wires for the license plate lights and that is plugged into the plug that comes from the rear left tail light. I tried tapping into the wires after the plug under the tail light, it didnt work. Then i tried before the grey square plug in the left cubby hole, the running lights work, but when i use the blinkers both rear lights flash but on an on off patter, where one is on and the other is off, and vice versa. Also when i hit the brakes the reverse lights come on.. but when i removed the ground, the reverse lights didnt come on anymore but the blinkers still didnt work right, i tried the trailer on my brothers 02 chevy silverado and it worked great. I hooked up my DMM to the harness i installed on my explorer and the brown got 12v when the lights were on, the green and yellow would get power with the left or right blinker and when pressing the brake. Im stumped and dont want to go spend money on a harness adapter when i can just straight wire it.