I ripped my pigtail right out of the trailer last summer when backing into the side yard when it got hooked on the trucks hitch receiver.
I started a topic thread on it if you want to read the whole thing:
https://heartlandowners.org/showthread.php/54483-Ripped-7-wire-pigtail-out-of-RV?highlight=Pigtail
The meat and potatoes start around post #83.
Here is a wiring chart:
(Pig Tail) - Trailer
(Solid White) - white
(Solid Black) - white with black stripe
(Solid Blue) - Solid blue
(Solid Green) - Green with white stripe
(Solid Red) - Solid red
(Solid Brown) - Red w Black Stripe
(Solid yellow) - Nothing Sometimes this is used as a back up circuit.
And here are a couple photos from that thread that might help as well:
And here is my junction box after I had it all wired back up:
I wound up cutting about 10 inches off of the pigtail and it still almost gets caught on the truck's receiver.
Here is a 'before' picture:
I now run a bungee cord across the back of the truck hooked to the two holes in the top of the each bed wall along the top of the tailgate and it keeps the pigtail away from the hitch, yet allows a little spring if it needs to flex a little.