# Headlight Quandry: Blub, Ballast or Invisible Gremlin?



## Audi_ATX (3 d ago)

Hello all, I am new to this forum and also new to owning an Audi (purchased used two days ago for a second ‘fun to drive’ vehicle) and I really need some help from some of you* gurus* on this siteI *This will be one of the first of MANY posts as I learn and work on this car.* I have already searched the forum for prior answers (none were here) so this is my first post. As a background, I’m semi-mechancial (average simple stuff) and I am active in the local Jeep community (I do love my Jeep and doing ‘Jeep stuff’) and I am often answering questions in Jeep forums and doing the same thing in that community as most of you are doing here. I hope to learn about this new TT and be of value here as well since each vehicle was purchased for a different use.

*CAR*:

2008 TT Roadster convertible (8J), 95,000 miles, automatic 6-speed transmission, 2.0L 4cyl

*CONTEXT*:

I just purchased this (used) two days ago in order to use as a fun second vehicle which I intend to become my daily driver. As mentioned previously, I love my Jeep, BUT 14-15 mpg, the aerodynamics of a cinderblock, and an engine built for torque (not speed) isn’t ideal for a daily vehicle. That said, the prior owners of this TT weren’t ‘car people’ and there are some items that I need to repair, one is the headlights…

*HEADLIGHTS ISSUE:*

I am getting a ‘bulb out’ warning light and it iseems to be the driver side high beam. I took out both headlight assemblies (driver and passenger) and replaced both bulbs (with a new base) using '_Torchbeam D3S HID Headlight Bulbs, 6000K Diamond White, High/Low Beam_” from Amazon (link here: Bulb Link). These are 35-watt Xenon bulbs that come with the base and they should be the same type of HID bulb with the metal stent base as the factory bulb. They were direct fits.

*Buuuuut*…. After changing both bulbs, here is the problem:

The bulbs/headlights shine at *two very noticeable levels of brightness*. The passenger side looks normal (dim setting) but the driver's side bulb is much brighter - as if it is stuck on bright while the passenger side is on dim.
When I switch the lights to 'bright' using the stalk on the steering column, the passenger's side light goes to bright but the driver's side is unchanged, it sets at the same brightness as it was already at (as if it is stuck on bright already???). It does not change from dim to bright or bright to dim - it just stays steady and pretty bright.
Also, when the lights are switched to bright, after about 10 seconds the passenger headlight (the only one that actually changes from dim to bright) automatically shuts off of bright and goes back to dim although the light switch on the steering column is still set to bright. It's as if it has a mind of its own. The driver side light just stays on at the same (and only) brightness it is already at. So, the passenger side won't stay on bright even when it's put there.
Finally, while driving, I noticed that the driver side light flickers off when I hit a bump as if there is a loose connection, however, I have checked and the connection for the plug is tight and in place and so is the connection to the bulb. I don't find anything loose.

*WHAT I HAVE ALREADY TRIED: *

I replaced both headlight bulbs with brand new Xenon DS3 bulbs, so I don't think the bulb(s) is/are the issue. To be certain, I swapped bulbs between the two headlights and the problem stayed exatly the same with no change and it didn't follow the bulb, so it's not a bulb issue.
I also swapped the headlight ballast between the two lights and again, the problem remained unchanged, so it doesn't seem to be a ballast issue either.
What am I not seeing here? Any suggestions or ideas from the group?


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## Robw516 (Dec 15, 2021)

I cant tell you with any certainty but I had a simular issue on another car. 

Check the sock/plug for the bulb is in good condition. I had one car and the plug overheated and melted. Sure you would of spotted this when you changed it but its something to check.


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## Audi_ATX (3 d ago)

Robw516 said:


> I cant tell you with any certainty but I had a simular issue on another car.
> 
> Check the sock/plug for the bulb is in good condition. I had one car and the plug overheated and melted. Sure you would of spotted this when you changed it but its something to check.


Thank you for your reply, I appreciate you taking the time. I have looked at the connections (where it plugs into the bulb itself as well as the plug into the main headlight assembly) and they are both in good working order, not burned, melted or otherwise damaged. I wish it were that simple and that I could find the problem that easily!


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## FNChaos (Nov 30, 2016)

It wasn't quite clear from your description, Did you have a “bulb out” issue before you changed bulbs, and if so what were the original symptoms other than the warning light (i.e was the bulb actually burnt out or ?)

Are your headlights Xenon dipped (low) with separate Halogen main (high) or do you have Xenon-plus (Bi-Xenon) headlights (i.e one Xenon bulb with a shutter for high/ low)


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## Wolvez (Jun 22, 2018)

The headlight bulb is D1S not D3S.


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## FNChaos (Nov 30, 2016)

Wolvez said:


> The headlight bulb is D1S not D3S.


Good catch. 

Which leads to lots of confusion & more questions: 

OP's mistake? Are the bulbs are indeed D1S or are the bulbs really D3S?
If D3S, then are the headlight ballasts OEM? if so what is the part number on them?

If your headlights are basic Xenon w/ D1S dipped (low) then your main (high) beam problem is with halogen bulb not your xenon (which has not been replaced).

If headlights are Bi-Xenon w/ D1S then main beam issue is with your headlight shutter since the bulb output doesn't change (there is no separate high / low filament in HID, just a shutter that blocks some of the light)

If the bulb is really a D3S then do you have an old halogen headlight with a HID kit? (what is the p/n of the headlight?)

If the bulb is really a D3S and everything else (ballasts, etc) all appear to be OEM, is there any sign that the bulb connector(s) have been replaced / modified? (a D1S connector should not fit a D3S bulb, and vice-versa...)


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## ebusch (Jul 1, 2007)

FNChaos said:


> If headlights are Bi-Xenon w/ D1S then main beam issue is with your headlight shutter since the bulb output doesn't change (there is no separate high / low filament in HID, just a shutter that blocks some of the light)


I had this issue with my lights. In my case the shutter in the driver's side light had failed, and the high beam would not activate. I think there was a "main beam failure" or some similar error message on the DIS. When I tried to enable the high beams, the passenger light would engage for a couple of seconds, and then automatically turn off again.


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## TT'sRevenge (Feb 28, 2021)

Wolvez said:


> The headlight bulb is D1S not D3S.


Was going to say the same, pretty sure they are D1S bulbs.

If the correct bulbs are installed and they look vastly different in terms of brightness and colour on each side and this still occurs with the bulbs swapped, it's probably the ballast.

Problem with HIDs is the bulbs can last for over a decade, easily. However once the bulbs age they become harder for the ballast to strike each time which puts unnecessary wear on the ballast. The only indication of the bulbs getting older is they tend to become more "blue" in colour temperature. In other words, HID bulbs _should_ be changed _before_ they actually "blow" because by the time they blow or go out, they may well have taken the ballast with them. Unfortunately nobody really tells anyone this so most owners would just keep on truckin' until a bulb actually goes out, by which time it may be too late to save the ballast or the ballast may not last much longer even after the bulb is replaced.

On another note, personally I would stay away from cheap, off-branded HID bulbs as well. Never really heard of "Torchbeam" as any kind of reputable brand so I'm guessing these are cheap China aftermarkets. Honestly it's a much better idea to just go with factory-spec Osram, Sylvania, or Philips bulbs. For a D1S yes they will probably cost $70-100 each which sounds expensive, but there's a reason they aren't like $30 like the aftermarkets...

If you need to replace one or both ballasts those will likely be prohibitively expensive new/from Audi but you can get used/yard ones off eBay, etc. for relatively cheap, which would probably be your best bet.

If there's a problem with the shutter in the headlight this is usually caused by broken wires within the headlight assembly. It's not super common but is not unheard of either. Sometimes it can be fixed easily, other times you have to basically cut/drill the headlight back to get to the wire(s) you need to repair, because they are inaccessible otherwise. Most electromechanical issues within the headlight will pop up a warning on the dash for headlight range or cornering, and also set fault appropriate fault codes.


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