Okay so here is the problem, I have had HID's installed for about 3 years not had a single problem, just the other night I noticed my high beam wasn't lighting, I un-plugged it and plugged it back up and it light so I thought problem solved. Tonight the hi beam did the same thing again, but this time I noticed, when I flip my switch, the ballast will make a loud buzz/zapping sound when trying to light the bulb.. Sometimes it will fire up and sometimes it won't. Any idea on what's going on? Bad bulb or ballast?

 

If the block hoots, and the lamp is lit every other time - a problem in a lamp.

 

Change places of connection of lamps to ballasts and you learn in what the reason.

 

sounds like a bad ballast, swap the ballast from your low beam to high beam and see if it works