The factory fog lights on the '01-'04 Elantra are wired in such that they only come on when two criteria are met: the parking lights are on and the low beams are on. They will not work with only the parking lights on, or with the parking lights and the high beams on. The way this works is that the fog light relay coil gets ground when the head light switch is in the low beam position, while getting +12V from fuse 6, which is only active when the parking lights are on. This DIY for eliminates the need for the low beams to be on to use the fogs, by relocating the relay coil ground signal from the low beam switch to chassis ground. This way, the fogs will work as long as the parking lights are on, and independently of the low beams or high beams. Check your local laws to make sure use of the fog lights is legal in this manner.

Procedure: 
                  

                                          
                                                                  
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