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Headlight bulb gone....only it hasn't....

Posted: Tue Apr 25, 2017 1:10 pm
by Kpowell911
Hello all, Strange one here, and one that come up the day before the MOT....

I have a 2012 Scirocco Bluemotion 2.0 TDI 140.

My drivers dipped bulb went and gave the warning light on the dash. No problem. I removed the bulb and it had blown so replaced it with a brand new one. Put the new bulb back in and it still doesn't work, still got no light and the dash light is on.... So I take the bulb out and test it using a 12v RC Lipo Battery. It works fine. I put the bulb in the holder and connect the battery to the holder and the bulb works so clearly the bulb and holder are fine.

The rubber bung has obviously fallen off when driving so is missing. Its possible that something could have got in to the light housing (moisture/ dirt) but I can't see a way of checking/cleaning the connections?

Has anyone got an advice? A google has scared me with ECU issues?

Thanks In advance.

Re: Headlight bulb gone....only it hasn't....

Posted: Tue Apr 25, 2017 1:19 pm
by Cuprabob
There are no fuses, so the controller may have shut the circuit down. It may need reset with VCDS but sometimes disconnecting the battery works.

Re: Headlight bulb gone....only it hasn't....

Posted: Tue Apr 25, 2017 1:27 pm
by Kpowell911
Thanks for the reply. If it was something like the controller as you suggest wouldnt more than one light be out? Its only my right dipped beam that the issue is with.

Ive also disconected the battery for half hour to no avail :(

Re: Headlight bulb gone....only it hasn't....

Posted: Tue Apr 25, 2017 1:33 pm
by Cuprabob
Kpowell911 wrote:Thanks for the reply. If it was something like the controller as you suggest wouldnt more than one light be out? Its only my right dipped beam that the issue is with.

Ive also disconected the battery for half hour to no avail :(
No, because the circuits are controlled separately from the controller. Each circuit has it's current monitored and if it exceeds a specific value then it will shut the circuit down. It's normally not an issue with normal halogen bulbs as they tend to fail open circuit. Normally it only shuts the circuit down if it detects a short circuit.

Re: Headlight bulb gone....only it hasn't....

Posted: Tue Apr 25, 2017 1:40 pm
by Kpowell911
Thats interesting. Guess I need a VCDS local to me to reset it :/

Re: Headlight bulb gone....only it hasn't....

Posted: Tue Apr 25, 2017 1:45 pm
by Cuprabob
I'll be honest, my money would have been on the bulb holder as those are notorious for causing issues but you say you've confirmed it's OK.

Re: Headlight bulb gone....only it hasn't....

Posted: Wed Apr 26, 2017 4:26 pm
by Kpowell911
Right, Go to my Mrs Dads Garage early, we put the right holder in the left light, and the left holder in the right light. Both lights worked and no error on dash board :) went for the MOT and I can happily report it passed with no advisories :)

Weird hey?

Re: Headlight bulb gone....only it hasn't....

Posted: Fri Apr 28, 2017 2:44 pm
by xjay1337
Electrics are strange at the best of times. Glad it's fixed.