So the passenger side headlight on my 2006 GS 430 has intermittently started not working. Turning the headlights off and then back on again reestablishes functionality. There is a lot of moisture inside that headlight housing.

I'm tempted to buy a factory new headlight for that side if for no other reason than to cure the massive moisture problem. But I also want to fix the headlight and I'm not sure how to go about it. It looks like a new headlight from Lexus does not come with a new ballast.

Any suggestions on how to begin troubleshooting this intermittent issue? I have a feeling everything will test normal if it's not malfunctioning at the time of the testing. I've got to remove the entire front bumper in order to replace the housing and I'd like to do that only once if possible.

 

An easy first step you can do is swap the bulbs to the other side and see if the intermittent shutting off follows it. HID bulbs do that when they're dying. Even though it doesn't address the moisture, at least then you'll know if it's a deeper issue like ballast/headlight/corrosion without taking off the bumper yet.

If it's the bulbs Formula J87 bulbs are a nice upgrade and cost less than OEM Phillips. If it's the ballast I don't know for sure if you can or can't, but when I was replacing my headlights I couldn't get the ballast connector out of the old headlight without destroying some of the AFS internals. It's a very tight space in there.

 

If you swap the bulbs and the problem stays on the same side then try swapping the ballasts and see if the problem moves then. Do u know how the moisture is getting into the housing? Make sure your bulbs are all seated correctly and the dust covers are all installed. Also look for any damage from a rock or something. If you can find the source of the moisture then you can dry the housing out by removing one of the bulbs and turning on the other to generate some heat and get the moisture to leave through the empty light socket. Then rectify the problem. I would definitely try to repair your housing and avoid the expense of replacing it.