I doubt that someone hooked yours up that way at the factory. More likely it was a modification such as I have done. I took the original setup (that I described in my post) and modified it to put the fog lamps on the high beam side of the headlights. I then installed small halogen high beam units in place of the foglamps and aimed them up and slightly outward. They work only with high beam and go out when I dim the high beams. We don't get much fog here in AZ and I need "elk lights" up at Alpine in the White Mountains when we are driving at night up there.

You could "bridge" the fog light wire so that they worked with either high or low beam, but you would need to install a heavy duty diode in each of the feed wires so that you didn't accidently "back" voltage up into both circuits. Optionally, you could rig up a relay or relays to do the same thing. You could also power the fog lights from a fuse that is only hot when the ignition is on. Omegabenz suggests the taillight circuit. That sounds OK, just be sure to increase the fuse amperage for that circuit to account fo the additional current draw. That might be the simplest. If your switch is like mine, it will only stay in the out (or on) position when the headlights are on. If you wanted to use the fog lights independent of the headlights you would need a separate switch.

Cheers,
Wes