Originally Posted by Tiger-Heli
Chaddz3 already did this on an S model and mentions a lot of the reasons for not using a vampire tap off the parking lights (I don't think it's a good idea off the headlights).
No reason that circuit couldn't be built without the switch if you NEVER wanted to use the headlights without the fogs, and I'm not sure why it couldn't be done under the hood if you preferred to, but you would have to find new ignition and parking lights trigger wires.
So really all you would need to do instead of running the trigger wire from the relay to the switch would be to run the trigger wire directly to the parking light with a fuse of course to achieve what hes asking? Which would negate the switch and turn your fogs on when the parking lights were on but not draw but an amp or so from the parking lights?