Possible Causes
WARNING: This page is about a different car, the 2003 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
FOG LAMP RELAY CONTROL CIRCUIT OPEN
FUSED B+ CIRCUIT OPEN
INOPERATIVE BULBS
FOG LAMP SWITCH SENSE CIRCUIT OPEN
OPEN FUSE
OPEN FUSED B+ CIRCUIT
CENTRAL TIMER MODULE
FOG LAMP RELAY