Okay, so I bought the GM hitch package for my Silverado and I have a question. On the instructions, it basically just says to remove the bumper plug and replace it with the included Wiring Receptacle. But it doesn't say how. I've tried turning it to the left and right and I can get about a quarter turn. I am presuming the black cover next to the license plate is where it goes. So how in the world does the old one come out? Thanks for your help!