My 2000 TT (brand new to me) started doing some strange things after the battery was replaced.  The interior lights will not turn on while the car is turned on and the alarm led's flash while driving.  The alarm stopped honking when using the clicker to lock the door and the windows stopped rolling down that little bit to let me enter/exit easily.  None of this is horrible but I thought before going to my local dealer, I would check the forums..  This is my first Audi and I am very excited to getting to know my car and talking with some you Audi Fans.

Sorry I can't help, but I am experiencing virtually the same exact problems a couple months after we replaced the battery in my wife's '01 TT. In addition to what you mentioned, it thinks the doors are open when they're not, and when she turns on the headlights, it alarms as if the car was off and the lights are on. So annoying. Now the brake lights have come on too and the battery dies, so it has become more than an annoyance. If I can't find a suggestion on where to look/probe, we're going to have to take it to the dealer. 

ANYONE? Thx

ANYONE?

I know there is a computer relearn procedure that can be done after you pull the battery but that is really only for drivability of the vehicle and not electrical issues.

Perhaps instead you should pull the neg battery lead and let it sit for twenty minutes unplugged, reconnect the battery, turn the key one notch to the first position and let it sit there for 5 minutes, restart the car, and see if you have the same problem. Be ready to get your radio out of safe mode so have the code ready. The procedure I just listed will reset your ECU.

If the battery is not keeping a charge, it could be the wiring harness from the alternator to the battery.  This harness also connects to the fuse block located on top of the battery.  The electrical gremlins could be a result of a faulty harness.  They tend to go bad.  You can check out the harness if you have a volt meter.   Put one probe on the large wire at the alternator and the other on the possitive post of the battery with the car running.  It should read about .06v.  This is the voltage drop between the alternator and the battery.  If it is higher, say around .15 or .2, then the harness is bad.  This is assuming of course that the alternator is not the problem.  Check it first by putting one probe on the large wire at the alternator and the other on the negative post of the battery.  This should read around 14v or so.  If it does, then you can check the harness as described.

Previously Eddie Blevins wrote:

><p>If the battery is not keeping a charge, it could be the wiring harness from the alternator to the battery.  This harness also connects to the fuse block located on top of the battery.  The electrical gremlins could be a result of a faulty harness.  They tend to go bad.  You can check out the harness if you have a volt meter.   Put one probe on the large wire at the alternator and the other on the possitive post of the battery with the car running.  It should read about .06v.  This is the voltage drop between the alternator and the battery.  If it is higher, say around .15 or .2, then the harness is bad.  This is assuming of course that the alternator is not the problem.  Check it first by putting one probe on the large wire at the alternator and the other on the negative post of the battery.  This should read around 14v or so.  If it does, then you can check the harness as described.<p>

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eddie:

thanks very much for the information! Last summer my 2001 TT suddenly died in traffic after losing power and the dashpod gauges going cuckoo (Battery light coming, on airbag light, then all warning lights followed by the tach needle jumping, etc.). I had the vehicle towed to Inskip Audi in Rhode Island where they said it was the alternator ($800 plus). I told them that I would have to think about it because I didn't have the money at the time, not really I just wanted to replace it myself and save the money. I picked the car up and I was surprised to find that they replaced the battery. I told him that I didn't authorize the battery replacement, and they just commented well we had to get it started to get it diagnosed! So I paid the $300 plus (for a $100 interstate battery with Audi decals on it) and managed to drive the car home hoping the battery wouldn't die (it was just a 20 minute ride).

So I took my old alternator out based on the vast knowledge of the Audi mechanic set Inskip, and bought a remanufactured one at AutoZone ($200 or so and a new serpentine belt). Replacement took about 4 to 5 hours.

A few days later the same symptoms occurred! I drove for about an hour... gauges started going wacky, and the strange thing is when I pulled into a parking lot the car started up after a few minutes rest. So all sorts of Internet searchs pretty much told me that AutoZone alternators were junk, so I took the new alternator out, and had bench tested at AutoZone and Napa. both places said it was fine. This has been driving me crazy! Especially when I read in different forums that people paid the dealership for two or more batteries, alternators, diagnostics, etc. WITH no results in fixing the car.

I came across your posting and I just did the voltage drop test from the battery to the alternator with a reading of .17-.20. Just to make sure I was doing everything correctly with the multimeter, I performed the same test on my 1995 Toyota T. 100 pickup. That test resulted in a reading of .05.

So, I just have to investigate further and either clean the contacts of that cable or replace, but I am so glad that at least I'm almost at the solution to drive this beautiful car which I've cursed and swore at for so many months!

Also Inskip also told me that I needed a new timing belt when they checked this problem I last summer. my car has 51,000 miles on it, and I took a peek at the timing belt when I replaced the alternator and the serpentine belt and it looked fine to me! I wonder if there is anyone out there that had their TT checked per the recall notice, and an Audi mechanic actually said "oh, your belts all set!" I doubt anyone! Why would Audi actually not say the belt has to be replaced? The dealer is going to make money for the service, Audi is covering their butt by preventing timing belt failures repairs, etc. I would love to get my hands on the Audi service bulletin of actually how a mechanic is supposed to look and inspect the timing belt and then have them do that right in front of me! Yes I don't trust mechanics anymore and I especially do not trust Audi Corporate (for example my claim to get paid for my new instrument cluster was somehow lost in the mail so that's 1000 bucks out of my pocket! ).

I remember reading in a post regarding the TT and the person wrote "they sure do look beautiful, even on top of a flatbed tow truck!"

thanks again, I will let you know how I make out with the wiring.