both HID ballasts dead

I can't work this one out. I've had HIDs fitted for the past 3 years or so. maybe 4. I've changed the bulbs a couple of times but for the MOT here (Finland) I need to have headlight washers for "xenon" headlights. so before each test I disconnect the HIDs and put the halogens back in. I did the same this year but took a couple of weeks to get round to swapping back over again. When I did neither side worked. I tried spare bulbs but still nothing. Halogens back in and they work fine. So how did both sides dies simultaneously? It was very cold for a few days (peaked at -30) but that's not unusual for January here and I've had no problems before with those kinds of temperatures.
I'm about to order new ballasts but would really like to work out what happened the existing pair. They were both completely disconnected for a couple of weeks. is it possible that the inactivity had somehow killed them?
very strange.

any thoughts welcome.


Well-Known Member
VCDS Map User
I know there is an option in VCDS for xenon headlamps - I wonder if the setting has changed to normal halogen if it has detected there are no xenons fitted?
Abit of a long shot - but may be worth trying.

Have you fitted both xenons together? The headlamps may require both to be installed at the same time to function.
thanks for your thoughts guys.
I'm 99.9% sure they didn't get damp because in -30 it's extremely dry. just friggin' cold :) And all the seals are intact.
The VCDS option wouldn't apply for aftermarket HIDs because the ECU doesn't know HIDs are fitted. The ballasts are just connected to the existing wiring to take the 12v feed.
it's a puzzler eh?
haha. no. def not mate. that was one of the first considerations. And unlikely i'd do both wrong simultaneously. The cost of new ballasts isn't a problem. It's a bit of a pain in the **** swopping them over because I have them installed inside the headlights and sealed. Looks like i'll just have to do that though. ah well...
not a fuse (one of the other first things I checked) and the halogens work so couldn't be the fuse.
broken wire is possible, but like a ballast failure it seems a bit odd that both would go at the same time.
I guess the only way is to fit new ballasts and as long as they work chuck the old ones and not worry about it :)