I was at the junk yard and picked up this power socket that was attached to the rear hitch. How is this power plug used for?

 

It's the 7-wire trailer wiring socket.

Did you unplug it from where it connects to the wiring harness behind the right taillight, or did you just cut the wires?

 

I disconnected it. I did not want to cut it.

what is the 7 wire trailer wiring socket do? (Sorry for the stupid question.)

 

Uh, it's used to connect trailers with 7-wire plugs to the vehicle's wiring harness.

Adapters are available to connect the more common Flat 4 trailer plugs.

 

Did I pull all the cords? See picture attached. Or do I need to also get the wire that goes to the fuse box?

 

You're gonna have a hard time using that without the matching "European 7-way round pin" plug. Here's a Euro 7pin to 4 pin flat(first or 2nd result on Google)

https://www.etrailer.com/Wiring/Tow-Ready/118710.html

 

Yep, pretty much useless here in the states. I'd be surprised if the other adapter (7 to 4) worked also, since other countries often have different wiring configurations...that don't match up with USA trailer wiring.

 

From the looks of the harvested harness, it's only taking 4 wires from the connector behind the RH tail light to start with, which kind of defeats the point.

 

I'd assume that's why there are 3 other wires after the Turn signal tap box.

 

My memory is that all the necessary wires go to the plug behind the taillight, so this harness makes it go 7 -> 4 -> 4+3 -> 7.