The reverse on my trailer will not activate. From looking at another truck and using a test light, I've determined that reverse is the center connector on a 7 pin round connector. The wire is black with a green stripe. My test light does not come on win I tap into that wire before or after the connector so that tells me that the connection is loose or open before the connector. Do you guys have any suggestions? Am I right on my assumptions of the wiring?

yes you are correct on the pin configuring. look inside of the wirring connector some of them only have brass pins or plates for a 4-wire plug( make sense?) if it is the one that comes with the truck I think that is the way it is. you will need to go buy one from a auto parts store or trailer store...where do u live???

Sorry guys, the truck is a 2000 model. I don't know what I was thinking.

All of the terminals in the round 7 plug do not work until you install the relays and fuses in the power box in engine compartment next to the brake booster. It is just a matter of pluging them in. The relays should be in your glove box from the factory if they were not removed and discarded. The inactive terminals are for the electric brake, reverse and 12v power leads.
The stop, turn and parking terminals are active.

USA1, Thanks for the reply. I have posted back in the General Discussion area because I was getting more feedback. I think your exactly right I just need to find the relays. I'm also missing the fuse that is for a Trailer Electronic Brake Control.

On the 2000 F350 I just traded I found that it was easier to run a power wire back from the front and hook it to a lighted toggle switch on the dash(powered off the aux power port and mounted next to it) and just wired a 2 wire light plug to the m/cyl on the trailer and used one side of the plug.

Slick 02, you might try looking for the fuses and relays we're talking about because they are not installed from the factory. You will find them in your glove box. I found mine, installed them and everything worked fine.

my psd has a 4 flat and the 7-pin round. When I wired a 5-pin flat, I just put the truck in reverse with the parking brake on and used a test light until I found the correct pin.