I have a weird problem with my A4, just as the title says, all of those lights tend to flicker, not necessarily on and off but rather dimmer and brighter. I can't think of anything that would cause this and am baffled by it. Just in case it has anything to do with it, I do have after market headlights, not just the bulbs but the whole casing and everything, you'll see it in my picture. Alternator looks new plus I don't think that would cause it either. Like I said, I can not think of anything that would cause this, and it's bugging me. Any help would be most appreciated.

 

Your alternator / battery could certainly cause this, and would be a prime suspect. The battery, followed by the alternator would be the first two things I would check in this instance. Included with the alternator check is to ensure there is good tension on the belt that drives the pulley attached to the alternator.

 

The belt tensioner was just recently changed, also the voltage reader on the dash reads 12V at idle and increases when I'm driving. The dash and radio controls do NOT have this problem though, just the headlights tail lights and the dome.

 

Have you done a visual inspection of the belt and tensioner to both ensure it's fully seated on all pulleys and touched the belt to ensure it's tight? Also, I would double check the voltage with a multimeter.

After that, I would then begin looking for faulty wiring behind the switch for the lights to the left of your steering wheel or perhaps a substantial intermittent load being placed on the electrical system without you realizing it's going off and on like a failing / faulty AC compressor clutch that has a mind of its own and engages and disengages at will.

I know this seems redundant and almost down right silly, but in my experience on these forums we can never rule out things without properly testing them first. I hope you understand. I would be certain the pulley was installed correctly and is still doing its job, followed by checking voltage with an independent meter.

 

So I did some investigating and I found out that the flickering is caused by the way the engine idles. And it only idles like that when the headlights are on. The engine also idle at the same rate the headlights are flickering. When I turn off the headlights, the engine idles just fine. I also checked that the belt had sufficient tension, and it did. So I guess a new alternator would probably fix the problem but, the it's already been replaced several times so I don't think it's necessarily the alternator that's at fault but the high voltage light bulbs.

 

Re-reading what you posted two posts ago, I should have realized what was going on. At idle you should still be seeing more than 12 volts on the dash because the alternator is being powered by the belt, which is being turned by the crank. This is a pretty cut and dry alternator issue.

Now that you have said the car has been through a couple of alternators in its life, this would lead me to believe that there is a tremendous draw of power that is killing them over time (Faulty wiring, shorts, etc.), or the voltage regulator has been swapped from alternator to alternator in an effort to save money. I have also heard of horror stories of people using aftermarket alternators and having nothing but problems time and time again. I would recommend going with Bosch as I believe they are OEM.

 

Hi.


It's been quite a while since you posted this thread but I happen to have a pretty similar problem now in my A4. So my question would be: did you find any kind of solution for the flickering lights? Thanks for your answer in advance mate.

 

There's a module under the drivers seat. It gets wet when your convertible leaks. Comfort system central control module. Your all welcome.