I've got a 2000 A6 2.7T that seems to have developed a small battery drain somewhere. I've put in two new batteries and so I am sure that there is a problem with the car and not the battery.

My local mechanic came up with what seems to be a plausible/good idea... he thought what was happening was that the relay switch to the internal air circulation system (warm weather package feature with the solar panels in the sliding roof) would not turn the ventilator motor off after the sun went down thus running the motor nonstop and discharging the battery. He tried pulling the fuses for that, but it still seemed to drain...

I'm still not convinced that isn't the problem... but anyway...

Right now I am in the process of pulling groups of fuses on Friday nights and rechecking on Monday mornings (I normally drive the car every day during the week) but this is a pretty long and tedious process.)

I was thinking I could try to put an ammeter on the battery and pull fuses trying to see if there's a noticeable drop at any point, but I need to borrow an ammeter.

Any other ideas/suggestions?

I've got the classic german car case of so many little nit-picky things going wrong, and I'm tired of getting reamed by the dealer on every one that I'm trying to solve some of these problems myself. (It's out of warranty these days obviously - while it was in warranty, I didn't mind so much bringing it in and having them fix it, but after paying to fix some of the little things, I just can't afford to keep paying the dealer boatloads of cash for this stupid stuff...)

-NavNut

 

Sounds like a logical aproach....Let me know if it works. I have a similar problem with my bmw....

 

Ok... so I've got this narrowed down considerably, but I'm still not there. After not being able to diagnose this with the ammeter (It always seemed to draw over 2 amps no matter what fuse I pulled - I ought to recheck this now that I've narrowed it down to a single circuit.) I tried a long and arduous binary search on the fuses... ie. - pulled half the fuses, let it sit for two days... see if it works... if so, pull the other half... etc... and divide and conquer, weekend by weekend, until I've gotten it down to a single fuse.

I believe it's the circuit with the Radio on it - I have a factory radio, and while I don't have the kick panel with me now, I think it's fuse #37 if I remember correctly. Seems to be consistent... leave the fuse in without starting the car for two days, and the battery dies... leave the fuse out while it sits for two days, and the battery seems fine.

I noticed something interesting though: in the kick-panel descriptions, it describes this circuit as something like: "Radio/cell phone". I have the factory radio, but I do not have the cell phone installed. I also noticed something interesting: If I pull out and put in the fuse repeatedly, I can hear a speaker clicking in the driver side door post. Now I THINK that the optional cell phone has a mic and speaker in the door post separate from the radio speakers. I'm wondering if some circuit for that option (the cell phone speaker amplifier???) may have failed and is now drawing lots of power all the time...

Since I don't care about the cell phone stuff, I'd be happy to cut any power wires to the stuff I'd neve use... Does anyone have a wiring diagram handy? Does this sound reasonable? Any other ideas? Let me know. Thanks.

-NavNut