If you look at the illustration on the fog light upgrade, there's two junction blocks by the brake pedal that they label C1/RB ( C1 right block) and they have you remove one pin from it, and add in one from the new foglight harness. It may be that it taps into that line that's needed for the fog to be powered? It just uses a common ground that's already there as well.
What does the FSM schematic show for that junction block and where does the wire you're switching go to is what has me curious.
The beatings will continue until attitudes improve!
HID Quad bi-xenon + foglight retrofit