Phantom battery drain
 

I see there have been a lot of posts about TT batteries that die after sitting a few days, with (and assuming a newish battery) the three primary reasons seeming to be (1) Bose amplifier, (2) alternator regulator, and (3) alarm battery.

I have pulled the radio fuse (42) and plan to let the car sit for a week. If it stays charged, is this a pretty good indicator that the amplifier is the drain?

Regarding the alternator regulator diode problem, would this cause drain if the car is off and sitting, or only if the alternator is running.

Finally, where is the alarm/battery in the TT Roadster?

Thanks in advance! I've had the car for almost a year, and so far have used this forum to fix the roof-open light (which also fixed the windows not going up all the way), using neo magnets to hold a compartment closed, and as a guide to planning to fix the pixel problem.

So, after letting the car sit in the driveway for almost 2 weeks (with the radio fuse pulled), it has maintained a charge and started right up. (Previously, the new battery would go dead in a week of sitting still.) So, it would appear I have a draw on the radio circuit. I could guess that it is a short in the amplifier, and buy another one, but those seem to run >$200 used, and it could be another short somewhere. Do you have any suggestions on how I could run a switch that would allow me to turn off the circuit without having to pull the fuse?

batterry Drain
 

I would suggest, use a multimeter, and disconnect the negative battery terminal. Then using your meter read the voltage drain across the meter with the negative probe grounded to the car, positive lead to the positive terminal with everything off. If you see a draw, then you start pulling fuses, until it stops. Once you have isolated the circuit, you can see what is being powered by that fuse.

Looks like I have the same problem. How did you end up resolving this?

I pulled the comfort control module (accessed from the trunk, behind the passenger seat). When I opened it up, I found corrosion on the circuit board. You'll see this is a common occurrence. Apparently the drains from the convertible top can funnel water towards the CCM.

Anyway, I sent the board off to ModuleMaster in Idaho, and they fixed it. www.modulemaster.com

Good luck.

Wasn’t my Amp
 

I have had phantom drain on my TT for a month now. It went to an Audi specialist who diagnosed a fault with the amp. Fuse was removed to stop the drain and I was sent away. Drain remained.
The RAC have just tested every fuse in the driver side panel and then moved on to the boot. He spotted the bubbling noise and I spotted the smoke!
Wiring junctions under the rear fuse box were sitting in water and shorting. Once removed from the water and wrapped up nice and tight (for now) the drain stopped immediately. Fingers crossed that is my fix. Thought I’d post in case it helps anyone else.