What I have is a receptacle on the interior of the wall that the bottom outlet is switched. I have a 3 wire coming into and out of the receptacle. 2 red wires on the top as well as a white on the other side, and 2 black wires on the bottom with a white on the other side. The grounds are tied together. How can I change it and wire up the GFI off of this one so that the indoor isn't switched and the outdoor one is switched?
You can pull off this receptacle as long as you use the constant power and its neutral (white) I would think it was the red seeing how the bottom you say is switched, but wouldn't count on it til I tested it. I would use wire nuts connecting jumpers to the existing receptacle and the new wires would be hooked to the line side on the outdoor GFCI. This would guarantee that if it trips it would not interrupt the interior circuit.