Originally Posted by malice9999

Having just taken my headlights apart today, I can tell you exactly what is happening. The condensation you see on the lens of your headlight is pooling at the bottom of the headlight causing your ballast to short out. I have the same problem in my passenger side headlight. The headlight "computer" that your dealer is referring to is actually a HID ballast w/integrated ignitor. Lexus conveniently mounted the most important (and expensive) part of your lighting system where water can pool with no drainage ports.

When I took them apart, there was corrosion all inside the "computer". I cleaned it up the best I could and dried it with a blow-dryer. After putting it back together there was an improvement - I could tell the bulb was trying to ignite from the flickering, but it was too late; the damage had been done. If you search on ebay, you can find an rx330 ballast for about $50-$100. These ballasts are manufactured by Denso and are actually very high quality, compared to some of the aftermarket stuff on the market. Unfortunately, they don't like water... go figure!

I tried sealing the headlights with some flowable RTV silicone, but I won't know for another week if they're still leaking. Luckily, I live in Seattle where it's either raining, or about to rain. My current plan is to purchase new ballasts on ebay, new lamp housings from Lexus ($440 ea.), and then transfer the "guts" (Projectors, AFS motor, bulbs, and of course the new ballasts) to the new housings. When all is said and done, I should be able to get away with new headlights for under $1000, which isn't bad compared to the $2400 I was quoted for two new complete headlights (parts only). Figure half of that for you since you only have one affected headlight.