Hi there,
here is some tricks how to get rid of flickering front headlight at night time.
First I did replaced D4S light bulb just to eliminate thoughts that bulb could be causing that flickering. No improvement ,still was flickering.
Now I try to get Ballast because at dealer they don't sell it separate.
The ebay was solution..... for about $60.00 one ballast was delivered in couple weeks.
procedure was quite simple :
-remove bumper
-disconnect on front right side (passenger side) main switch white connector carefully. disconnect fog lights connector.
-remove headlight
-remove screw which is holding level rode( in order to get old connector out from headlight assembly) ...HERE WAS PROBLEM BECAUSE I DID NOT HAVE TOOL TO REMOVE THIS BOLT WITH VERY STRANGE SHAPE......SOLUTION WAS TORQUE BIT (T# 27)
-remove old ballast with cable and feed new cable of new ballast thru same way.make sure at this point to get seal on the bottom of ballast straight that water not coming in.secure it with 4 philips screws.ALSO MAKE SURE YOU PUT BACK THE GROUND CABLE ON THE BALLAST (SHIELD) .
-at the same time I did upgrade my fog lights using plasma LED.
NOTE HERE FOR FOGS:
-we have removed small heat shield inside fog light assembly because the new 9006 LED bulbs were projector bulbs.Just to get more light (lumens) I guess.

now we put all back together .
and we lost day driving lights.......lol ....the way it works after 5-10 min. of driving those day lights will come on.......could be computer sampling voltage and learning voltage after white plug was disconnected not sure at this point.

so all works ..NO MORE FLICKERING ...PROBLEM SOLVED.
here is some picks to help you solve this issue with lights.
​​​​​​​cheers!!!!

 

Just type in search field on ebay this:
"2006-2011 Lexus GS300 GS350 Xenon HID Headlight Ballast Control Module NEW"


and that was great match for 2008 gs450h ballast.

​​​​​​​so far works great.

 

I really want to get a OE ballast made in Japan but the problem is that so many Lexus' have this ballast problem it is now a common issue so if getting another used ballast from an old Lexus, that will increase the chances of the same problem happening again. I found this one made in Japan with 1 year warranty.
http://www.ebay.com/itm/272327636401


The other alternative is to get a new aftermarket ballast made in China.

I can't even believe how frustrating this experience this is. I want to buy Japan OEM but they have a history of failing so I have no choice but to buy aftermarket. Even on Amazon the OEM Denso listing has reviews saying failure post-installation.

Thoughts? Anybody?

 

I had the same issue. My left headlight would not come on dispite replacing it with a new one. I took it to a local HID shop to see if it was a bad ballast or headlight
They found the fuse was blown. They replaced it and now it works like normal. Only paid $35 for the diagnostic