also, some factory and/ or illuminated switches require them to be wired on the ground side for the illumination to work...

I just did the Fog lights in my '98 Ranger. factory lights, but I built the fog light harness.. triggered off of 1 of the park lights for now, but when I get the money for the factory radio bezel w/ fog switch, the switch needs to operate the ground, so the illumination and indicator light function. so for it to function the way I need, there needs to be a diffrent relay to trigger the current 1, so the fog light switch can control the ground circuit