I think you mis understood. I didn't have my fog lamps grounded to battery. It is just them getting blown up from a deer which lead me to discover broken / cooked fender to batt ground
Had the same issue recently. I hit a deer and blew my fog lights that I had located in my bumper holes. After that my needles on guages were whacky. Low oil pressure. Low voltage. Hard starting. Headlights would go dim. Found that my ground wire from passenger battery to fender had cooked itself...