# 2000 Audi TT battery drain



## diptenkrom (Apr 1, 2018)

So long story, but I will try to make it concise.

I have a 2000 Audi TT 1.8t Quattro Coupe, that I thought I had solved the problem on. I started here on the forum and checked all the usual suspects, and now 2 batteries later, and about $550 other wise spent, still have a drain. 

The car had no AC, heat, and found out no cooling fans or thermostat when I started digging into the issue to fix the AC. After having replaced the cooling fans, thermostat, voltage regulator, coolant thermoswitch, and fan control module, and flushing the cooling system, I had functional heat and fans that worked and car that actually got to operating temperature. I had the AC vac and fill done at a local shop I trust, and it still didn't work. Somewhere around then is when I started having battery drain issues. I took the car to a specialty shop local to me, in order to get the AC and battery drain diagnosed. They told me that the Gauge cluster and the AC compressor were bad, and causing the drain. I took it home and I replaced the LCD and the coolant temp servo on the cluster and reinstalled. I have been driving it with that cluster for a few weeks. Have had no issues with power since then. I had the compressor, expansion valve, and accumulator replaced by a friend of mine yesterday. Car drove after this, but I didn't go far. Went outside this morning to go to work and the car was dead again.

The only thing that has changed electrically since yesterday is that the AC compressor was plugged back in after it was replaced. Which means to me that the AC compressor clutch is locking down again, and there is something else causing it to do so. I don't really trust the specialty shop to touch it, since they charged me $350 to diagnose a thing that is not fixed after replacing what they said the cause was.


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## QCOUPETT (Dec 21, 2012)

*Do you have an after market stereo?*

Also check the UK forum- lots of battery drain posts there. Also, if no luck, check with Wak in the UK: [email protected]. A TT wisperer....


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## diptenkrom (Apr 1, 2018)

Thanks for the reply, I was beginning to think that nobody had any ideas. I have found some threads where people have had this issue, but they were either different car and generation, or there was never a follow up that posted the solution. Is there a relay for the AC comp clutch?

I have a factory stereo. nothing aftermarket on the car except the diverter valve and exhaust at this point. definitely nothing electronic.


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## QCOUPETT (Dec 21, 2012)

*OK*

Might be a bad ground or something. If all else fails, check w/ Wak.
Good luck


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## diptenkrom (Apr 1, 2018)

who is Wak? 

i was thinking if it was a bad bround it might not activate, but would that make it always on? is it negative switching system? usually stuff is positive switching, and the negative is just a solid connect to ground. does VW/Audi use a negative switching commonly in stuff?


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## Converted2VW (Apr 8, 2009)

FYI from another battery drain thread:
*
Since he has a coupe, it's less likely that it's the CCM.

I solved my battery drain with a multimeter last year.

Step 1: Car off, everything else turned off, trick the car into thinking it's closed with the door open and get access to the fuse panel.

Step 2: Remove your negative or positive battery cable (I prefer the negative post, but since we're measuring for amps, it shouldn't matter)

Step 3: Set your multimeter to amps; you'll want the fuseless circuit, so you may have to move your lead to the appropriate place on the multimeter

Step 4: Put one lead on the bare battery post, and the other lead on the disconnected cable end (I had my girlfriend hold my leads on their respective spots and watch the multimeter to save time)

Step 5: Wait for the car to shut off (dome lights off, radio off, car thinks door is shut)

Step 6: Narrow down your current draw to a circuit by pulling fuses one at a time until the draw becomes less than .05A. Search this circuit for shorts to ground and repair/replace the wire/component as necessary.

We narrowed mine down to fuse 42, which is the radio/amp fuse on our car (same year and motor here). After pulling fuse 42 my battery stopped draining, but I had no radio. Later last winter I did my heater core, and while I had the dash apart, I noticed a few wires that led to the back of the head unit had no insulation around them (they originally had a foamy wrap around them, but it had since deteriorated and all but vanished). I wrapped the bare wires (one was a small nut and bolt junction) with electrical tape, put fuse #42 back in, and have been enjoying my radio every since with no battery drain(well, I need a new door speaker, but hey).

If you narrow yours down to the head unit/amp, the tool is super cheap to pull the stereo, and a few torx bolts and that entire area is pretty easy to dismantle.*

Also, Wak is a TT owner in the UK that has put together a really helpful TT site: search for Wak TT


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## diptenkrom (Apr 1, 2018)

Converted2VW said:


> FYI from another battery drain thread:
> *
> Since he has a coupe, it's less likely that it's the CCM.
> 
> ...


Thakns for the info. 
I did essentially this procedure, and i know that the drain is related to the AC compressor clutch, what i don't know is what is left to switch the clutch on, even when the car is off. Where is the relay or switching coming from? ultimately i want to have AC and not a draining battery and ac clutch that eats itself.


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## TheDeckMan (Sep 26, 2004)

Converted2VW said:


> FYI from another battery drain thread:
> *
> Since he has a coupe, it's less likely that it's the CCM.
> 
> ...


Luis, this should also would be a great addition to the FAQ sticky.


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