OK, check photo. The factory 4 pin plug on my Excursion is the opposite of all other trucks I have seen. The trailer plug will not fit into it without some sort of male to male adapter. My buddies 05 F350 is different. In the photo the one I am holding underneath is from the trailer-its the same damn plug!

Whats with that??

photo in my garage, tried to attach it here but its huge and blurry

 

No, that looks correct. Your trailer plug has some sort of cover over it though. The plugs themselves are different though. Your Ex plug has one prong and three sockets, where your trailer plug has three prongs and one socket.

Cut some of the rubber surround off from around the trailer's plug to expose more of the prongs. It seems this is a common problem though because someone did that to my black Ex before me. I say cut the trailer plug up because if you do the Ex's plug, then it gets dirtier and corroded easier when you aren't pulling the trailer.

 

The pic in question...

 

I have seen those connectors. The "sleeve is supposed to slip over the male (truck in your pic) connector normally but doesn't work with some connectors like the one you have on your truck. What I have done is just cut the sleeve off the female (trailer connector in pic) connector then it will work.

 

Your trailer plug (on right) would plug into this truck connector because ti is made for it. You can see in the second pic what you would have to cut off your trailer plug to make it work.

 

If you're concerned about cutting anything, you could get one of these adapters for your 7 pin.

Pollak 7 Pole to 4 Pole Connector Adapter Pollak Wiring PK12716

 

That's what I used when I found my 4 pin to be corroded and faulty, easy too.

 

I have one of those as well and also prefer it over the factory plug. I also have a whole array of 7 pin to 4 pin male and female plugs on both sides, 4 pin wire extenders and converters, and such, I pull quite a few different trailers and always seem to need a different plug or connector. My favorite to use is the 7 pin to 4 pin with about a foot of wire between the two. Seems to be the right length for most of the 4 pin trailers I pull where the 7-4 pin with the 4 pin built into the 7 pin sometimes falls short of the trailer wires reach.

Along with the lugs and wires I have the same array of receiver hitches with different drops and ball sizes. lol