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Matt, Engineer
Category: Audi
Satisfied Customers: 21726
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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We have a 2000 Audi TT. The other day while my wife was

Customer Question

We have a 2000 Audi TT. The other day while my wife was driving the headlight warning light came on. This happened during the day but my wife always drives with her headlights on. Tail lights work just fine. During my troubleshooting I have noticed a few things. Sometimes both headlights would not come on when selecting on, sometimes the left headlight would flicker when coming on. Also, when you turn the key off and your headlights are left on, you will get the warning buzzer but the headlights went out when I turned the key off. This is strange because in past the lights would stay on during the buzzer warning until you actually turned the headlights off.
Does any of this make sense?
Greg Abbott
Submitted: 1 year ago.
Category: Audi
Expert:  Matt replied 1 year ago.

Hello Greg

I'd 1st check that the connections to the gas discharge control module behind each lamp as these are high power connections and can corrode, check and clean the earth connections for each module

Customer: replied 1 year ago.
Matt, are you online?
Customer: replied 1 year ago.
Customer: replied 1 year ago.
Would be nice if you would respond or at least give me a hint you are interested in helping me?
Expert:  Matt replied 1 year ago.

Hello Greg

Sorry but I'm in the UK so was in bed at the time

how can I help, have you investigated the connections as I've suggested?

Customer: replied 1 year ago.
Matt, I had no idea you were over in the UK, I'm in California. I wanted to pass on to you that I noticed the left headlight seemed a little dimmer than the right. Also, a few times after I turn on the headlights within a minute the left headlight goes out. Once again, this does not happen every time I turn the lights on. I did remove the lamp from the vehicle and have it with me in the house.
Expert:  Matt replied 1 year ago.


OK thanks for the extra information, I'd say that this sounds like a faulty ignitor unit for the gas discharge headlamps

this is a seperate box that is just behind each headlamp and the wires run from the loom, into the ignitor box an onto the headlamp

Customer: replied 1 year ago.
I have attached a picture. This is the igniter, correct? This requires the removal of the whole headlight assembly, correct?
Expert:  Matt replied 1 year ago.


thats the correct part, I've known ignitor units to fail like this so they only work for a few moments then switch off as they overheat

Customer: replied 1 year ago.
the answer to the second question? Do I have to remove the headlight assembly? Also, my original question had a question in there about why the headlights now go off when you turn the key off but the warning buzzer continues to sound until you manually turn off the light switch? This is all new, as the headlights have always stayed on after you turn the key off with the buzzer warning making noise.
Expert:  Matt replied 1 year ago.


you can just squeeze the ignitor out without removing the headlamp but its far easier with it out

and the buzzer is only wired to the switch and not through the headlights themselves so really its a buzzer for the 'lights left in the on position'

Customer: replied 1 year ago.
Okay, thanks for the info on the igniter. I understand the buzzer is wired thru the light switch so it would sound off if lights are left on when ignition switch is selected off. However, my question was, why do the headlights go out after you turn the ignition switch off while the headlight switch is still selected on? This is not normal......
Expert:  Matt replied 1 year ago.

Aah Ok

I understand your question, but yes you're correct that is not normal

if the car has aftermarket lights then these can be wired differently?

if its the original Audi unit then its likely the fault is related to a faulty ignitor unit

Expert:  Matt replied 1 year ago.


do you still need help?

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