Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, headlight low beam problems in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; hey everyone,
my driver's side low beam is out. took the front end apart and replaced the hid xenon bulb....didn't ...
my driver's side low beam is out. took the front end apart and replaced the hid xenon bulb....didn't fix it. swapped the passenger side to test the new bulb(it worked) and neither bulb worked on the driver's side. checked the 20 fuses for both left and right, both good, even swapped them, both good. still no working headlight.....what next.....besides the dealer that I just got back from valve cover gaskets and they said nothing about the headlight even though I know they checked it. I keep the headlight switch on auto, and when I got the car back it was off.
So I took the front apart again to check the ballast.....swapped it with the other side and problem solved....almost. the bad ballast was drenched with water...pouring off. So the moisture problem is the cause. Since I had it apart, and I dont have the new ballast yet, I put some silicone around some of the edges and will wait to see if it helps before I replace the ballast. Might need a whole new housing.
If it was that drenched, yeah a new housing maybe in store for you. Try finding where the moisture might of found its way in first. Seal that up and see what happens. Just make sure you don't seal up any vent holes, including from the ballast to the housing. If there are any, it's been a couple years since I took them apart.
I know there are some in the back of the housing, they should have little one to two inch tubes attached to it with a angle downwards.