Following this link in your best bet! you might be missing the small connector that the wires go in. I remember doing the same thing with my harness and the small screw driver. Don't give up, you'll get it.
I had some what of the same problem. I ended up shrink wrapping each of the wires separate so only a little of the connector part was visible. then I was able to slide the female end in to the male connector side, and secured everything together. I didn't want to cut and splice the wires if I ever decided to go back.
* NOTE * mine is a 2010 so the color of my wires are going to be different.
In the first picture below it shows the old connector (the one you had to de pin) on the bottom. The top two wire connector is the one off the GT500 harness. The two wires you de pined from your old harness plug in to that one. and the old connector just sits there.