How to diagnose fault with bi-xenon?
 

Hi chaps. My n/s bi-xenon has gone out with the bulb failure light in the driver warning panel. I've got VCDS. Can I diagnose what's gone using VCDS, or is it pretty obvious what it is? Basically normal beam is off on n/s, but hi beam works fine both sides (although there's a blown sidelight too on n/s)

I'm not familiar with xenons, so any help will be most appreciated as always.

I take it I'm correct thinking it's bi-xenon? Pic attached

Vcds is unlikely to tell you much about the state of the bulbs, but you could try it. The headlight aim controller failing is more common, but that doesnt cause a lack of illumination, so you're either looking at the bulb being faulty, or the ignitor that gets it going (bit like a normal household floresent tube)

You could change the bulbs over from n/s to o/s and vice versa to see which part is faulty.

When you say hi beam still works, I guess you mean on flash, ie pulling the stalk back? - If you push it forward to hold main beam, that should work with the same bulb as dipped beam, and i'd be quite confused if it was igniting for main beam, but not for dipped.... When your 'flash' hi beam works, it should be a seperate Halogen bulb that works for that.

(its the use of the same xenonbulb for main and dipped beam + a seperate 'flash' halogen that makes the xenon plus, plus... !)

Interesting you have a side light out too - Not sure if that was an incidental comment, or part of the diagnostics, but maybe a dodgy earth?

Hope that helps....

Hi Ian, (belated) Happy New Year +++

Thanks for your help, I've just been out and swapped the bulbs (never seen one before - funny looking things...).

You're correct - switch to full beam, the halogens kick in as well as normal beam. Flash and the normal beams lift up along with halogens (in this case only one side lit & lift).

It's a bulb that's gone - I could tell by looking at it actually, all powdery and funny colours inside compared to the other side.

So, I'll price up some new ones (I'll get both sides to match).

PS. Sidelight is blown, can see break in filament.

Cheers again ;)