I don't have any foglights, nor the wiring to have them, so pardon the following question.

I had installed an HID kit that ran the same style harness as the Putco one. Wires went to the battery, there were two grounds, and there was one H4 plug that plugged into one of the two factory headlight plugs, then, there were two empty plugs you could plug your headlights into. So, in short, it had the same wiring concept in mind.

I still had the problem with the high beams listed above. So it does strike me as odd that it would be a "foglight-only" problem.

Considering the wiring harness for the HID kit was basically identical, add ballasts, what would have caused that in my situation? It's actually the main reason I moved to the LED plug-and-play housings by TruckLite.