If you have a DMM (multimeter) or 12 volt test light the best thing to do is check for 12 volts at the fuse socket to make sure the fog lamp switch is good. After that check the fog light relay to see if it is energizing. You can jump the contacts pins 87 and 30 of the fog light relay to see if the lamps will come on for troubleshooting purposes. Make sure ignition is off first before jumping relays. Also, are the low and high beams working properly. If the high beams are stuck on it will inhibit fog lamp operation.