I've got a '99 TJ Sahara.  Fog lamps started acting up last fall.  Throw the switch and they wouldn't come on.  Leave the switch on and later you might hear a snaping noise and then they would come on.  As weather got cold, they won't come on at all.  I've changed out the switch but that was not the problem.  Don't want to take this into the dealer as they would probably charge me an arm and a leg for a cheap fix here in Chicago....