for some reason I want to say the wire you are looking for is brown but I may be wrong, I'd need to double check that. keep in mind though, that because its factory, your headlights circuit is able to handle the increased current when the fog lights are on, but your parking lights aren't designed for it and may not be able to. on my fog lights, I tapped that wire that is hot when parking lights are on (headlights too since the parking lights are always on with the heads) and I used that to energize a relay to give my fog lights switch power. so then the fogs turn on whenever the switch is on, but if the parking lights are off, the fog lights are off no matter what positition the switch is in. works great for me. I like to use the fog lights in lower visibility situations when running the full headlights is an overkill. anyway, I suggest you use a relay to power the fogs, and energize it off of the parking lights circuit, that way you don't have to worry about blowing a fuse and being without any lights at all when you really need some.
