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.