How can I bypass the parking brake wire?

I have a Pioneer AVH-P6600 and I've tried to use a 3 prong switch in order to "turn on" and "turn off" the parking brake check wire. There is a positive prong, a negative prong, and a positive out prong. I connected the negative to the ground wire on the radio and then connected the postive to the power wire on the radio and then i connected the parking brake wire to the postive out prong. I have tried toggling it on and off 3 or 4 times and I still can't view video. Can anyone please clarify how I need to do this using the switch? Preferably using the switch I have now because I have already installed it (cut a hole in my dash to make it fit).