[GeoNY]

I washed my '05 300C, and later that day I noticed water on the inside of the driver's side headlight cover. While driving that night the driver's side headlight (HID) suddenly turned off. I bought a new bulb and installed it, but it still didn't work. Pulled the fuse to confirm that it's working fine, which it does (passenger side parking light works with fuse in, doesn't work with fuse out) so I put the fuse back in. Now I'm exactly where I started, moisture has re-appeared in the cover and still no working low beam on the driver's side. Any idea what else I should check and/or do?

 

[GeoNY]

FYI there was no water at all in the cover when I installed the new HID bulb. Everything looked dry at the time.

 

[JL-KA]

The ballast is in the bottom of the light. You probably fried it.

 

[Kaiser Bill]

you can take everything off the kight, remove it & heat it in the oven to drive off the water, then go around the edge seal with silicone. Test the bulb in your opposite headlight - if it works, your ballast has blown. This is bolted to the bottom of the headlight. The ballasts can be pricey & you MUST count the pins on its plug before you get another, as they come in 12 pin or 4 pin.

LAD5GL = 4 pin

LAD5G = 12 pin

lad5gl | eBay

lad5g | eBay

if theyre too rich for you, you coud try a replacement ballast (oem) for your D1S bulb.... example HID Xenon Replacement 35W D1R D1S Slim Ballast for D1R D1S Bulbs w D1 Plug Wire | eBay