After I posted that I thought there might be a naming issue. What you are calling fog lights are the white light the lights up when the car goes in reverse right? If that the case I've never heard them referred to as fog light just back up or reverse lights.
Nope they're reversing lights. The rear fog light is a high intensity red light, on a VW it's usually two pulls out of the headlight switch. First one turns on the front fogs, second pull turns on the rear one in addition.
Here's a random Tiguan picture I borrowed from a google image search :
It's the really bright one at the lower right of the left cluster.