[jamblazer]

Bought 2003 330ci in May 2014 with 62,500 miles. Read on this forum about how to reset Inspection Light, which involved turning ignition switch on and off...nobody mentioned to turn off Auto Headlight...after about three times, headlight warning light came on for driver's side...opened hood, and xenon bulb and holder were loose and out of socket. Put bulb and socket back in, but no light. Bought new bulb from parts store, but did not work at first...after turning switch off and on, got it to work one time, but then turned it off, and has never been on again.
Reading this forum has me petrified to go to dealer 60 miles away and have them convince me I need a new headlight assembly...so I have about convinced myself to try and fix it myself...gulp...I have read that it probably is the ignitor, ballast, or control module.
QUESTION: Should I buy both a used ignitor and ballast on eBay, or does anyone have a similar experience that can help me diagnose why light will not work.

 

[Solidjake]

Looks like you've read up but you're missing an important step. Swap the bulbs around and see if the problem moves or stays. if it stays swap ballasts, ignitor, etc then you will know what part is wrong. Also make sure to check your ground on your tail lights since that affects the headlights as well.

 

[ac_2007]

Don't buy anything yet.

I was pulling out my hair trying to diagnose failed xenons on my M3.
In my case, I removed the ballasts, the ignitors, swapped them, did electrical load testing, voltage drop testing...

...and it turned out to be TWO sets of cheap D2S xenon bulbs.
I put back in the 14 year old 4300k Osrams that my 325i came with, and the M3's headlights worked flawlessly.

Don't use cheap bulbs!

 

[eneka]

It could be either the ballast, bulbs, or ignitior. It was probably already on its last legs and when you cycled them, they gave out. If the bulbs are original I'd swap them out as well since they lose their output over time. These are oem bulbs.

 

[jamblazer]

Thanks for the quick, helpful replies. Still considering options...may start with another bulb first, after checking taillight ground!! Thanks again for the info.

 

[jamblazer]

Ballast probably failing, but found work-around

I have been able to consistently get xenon bulb to work using Manual lights...I turn on lights to parking, then to full lights. Once it flickered, and once it failed to come on, but each time I went back to parking, then to lights, the xenon came on and stayed! Reminds me of the old florescent lights where you had to flick the light switch to get the lights to come on when the ballast was going bad. I think the Auto feature attempts to switch on bulbs first time, and since they usually do not fire the first time, I get the dash warning light and no more attempts. Diagnosis probably points to failing ballast, but this works for me for now, so I am done. This is my play car, and I do not use much at night. My solution will probably not help anyone else...sorry. Thanks again for all who offered suggestions.