Help on Repairing Xenon Headlight
 

The driver side Xenon headlight of my 1998 E-320 will not light up more than 3 seconds. Most of the times, it will go dead as soon as I turn it on. When it can stay on for 3 seconds, it light up with bluish color but cannot turn to whiter color as the other does before it dies. I don't know if it is caused by the defective bulb or ballast.

I tried several times to open the headlight assembly but without any success, especially because the opening behind the assembly is very narrow and the cold weather is coming in.

Does anyone have suggestion on how the Xenon system works, how I may diagnose this problem, or have a detail procedure on fixing this problem so that I may get educated?

Thank you very much for your help.

I do not know specifically your car but I know HID theory; I presume you have Zenon HID. If this is the case, the light fixture is composed of a variable voltage ballast and the light element (bulb) itself. The setup is similar to an arc-lamp or florescent lamp, where the initial power is used to vaporize and then ionize the gas in your bulb. Then power can be cut back as the RXN stabilizes. That is why they take a few seconds to come on to full power (when cold). Also, the high beam uses the same element as the low beam, just at a different voltage and current.

From the symprom, it sounds like the bulb may be broken (possibly cracked) allowing the precious gasses you want to energise to escape; that may be why it only works for a second or two (as the gasses energise they expand and escape) and then die. Otherwise, it is very unlikely the ballast would break; but I cannot gurantee this. Also if it was the ballast, I would presume the light would do nothing at all.

Isn't your car still under warranty?

Good Luck!

Adam

Thanks, Adam.

My car was just out of warranty a few weeks ago. The dealer wants 1.5 hours to diagnose the problem and another 1.5 hours to do any repair. They think that I would need to have the whole assembly replaced.

Do you know any procedure to fix Xenon headlight? Because it is just a bulb, I may try to do it myself, although my technical skill is almost zero.

Thanks for any suggestion and advice.

I do not have experience with your model, but I'd presume that there is some type of fastener that is meant for easy removal (knob-like) that affixes the bulb to the fixture. If you can see the back of the fixture, experiment and observe how the bulb is held on. If the ballast is attached to the back of the fixture (blocking your path to the bulb), you may have to remove the entire fixture, with ballast. Remember that if you are doing this yourself USE CLEAN RUBBER GLOVES TO HANDLE THE BULBS!!! HID lights, like halogens, Hg, or Na vapor bulbs, get really hot. The oils from your skin will get onto the bulb lens and absorb light and convert it to heat thus reshattering your bulb you just repalced where you touched it. This may have been the case if your bulb had been replaced before (perhaps by someone not as carefull as we'd like).

Also, if you end up having to remove the entire fixture, you can always take it to a shop to have the ballast tested. Or if you can, you can try swapping bulbs with the bulb on the working side of your car. If, by testing you discover the working bulb does not work in your other socket (the questioned side), you either have a poor connection (unlikely in a 98') or a damaged ballast (also unlikely).

Worst case senario, you need a new ballast and you have an extra bulb.

Good Hunting
Adam

Thanks, Adam. Your advice is really valueable. I would try to find time and right weather to do what you have suggested.

A Different Approach...
 

If your car is only a few weeks (or a few thousand miles) out of warranty, then I would try and get the dealer to fix it! Many times they will. Try a different dealer.
I have heard that Mercedes-Benz dealers have been pretty good about this.
GOOD LUCK!

Thanks David for the suggestion. I will try it to see if the dealer may want to do it.

I tried to call the dealer and they refused to do it. I guess I would wait for warmer weather to look at my headlight. Right now, one Xenon plus fog lights are bright enough to illuminate roads at night. Thanks.