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im using the etrailer wires. it looked a lot easier to install than the oem and it had good reviews.
For unpinning, if you are looking at the harness from the side of the pins and not the side where the wires come in, you should see a piece of plastic thats in the middle of all four pins. pull that piece of plastic out. If you know how the pins look, you would know that they are kind of like a fish hook. to remove them, you have to the push the pins downward or upward towards the wall of the harness depending on which way you are holding it. they should snap off and come loose fairly easy. once they are loose, you can pull the pins out from the back of the harness by the wires. reconnecting them is the exact reverse.
i am using the oem trailer hitch as well, to keep wires in place at the hitch, i just routed them through the original bracket. The wires just hang there perfectly.
good luck