I bought a fog light kit for my 97 GLE from Courtesy and installed it. Only the passenger side light works. I called Courtesy thinking it was a bad bulb and they told me to swap them around. I did and only the passenger side worked again. That means there is a problem with the wiring. Any suggestions on what could be wrong? I am taking the car to the dealer a week from tomorrow and will try and get it fixed but I would like to do it myself if I could.