I recently purchased an 02 A4 1.8T and am experiencing a battery drain if unused for about 24 hours in the winters (been seeing temperatures pretty close to freezing)

Did a search and nothing to explain the below...

Some background on the diagnosis:
- battery, alternator, starter tested and all reading look ok
- Disconnected the alternator but drain continued
- Radio was removed and replaced by dealer in the past

There is something weird I saw with the current drain test when pulling fuses. When I remove the fuse for the instrument panel lights, the climate unit actually lights up. I suspect this could be a short but wanted to see if anyone knew wheter this is supposed to happen? If not, I am guessing I'll have to get a hold of the radio removal tools and check the wiring...

I also have the notorious slowly blinking hazard switch which stays on after i lock the car... I disconnected that as well but the drain continued.

Do you think this is a short behind the radio/climate unit? Doesn't make sense to me that the climate control lights up when the fuse is pulled for the instrument lights..

Any and all help much appreciated!

 

Eeek, not good. Are you sure that the battery was load tested? Any idea on how old the battery is?

If the battery won't hold a charge, it could produce similar behavior.

 

Have you done a draw on it? Hook up dvom test in milliamps. Put poss probe to negative cable, negative probe to terminal. Should read about 0020. Cable has to be disconnected. If you have more than stated start pulling fuses. That should show culprit.

 

the battery is actually about a week old.. having just bought the car, i figured id just replace the battery since the previous once was at 50% life... the new one has been tested to ensure that its good. when it does die, i slow charge it back to life (has taken about 4-5 hours) to avoid strain on the alternator

i did run the current drain test (create a series between the negative terminal and probe and measure the current there)... and saw this weird symptom where the climate unit lights up

question about the mA number you quoted -- how long after the car has been switched off, doors closed, and armed? The fuse test is kind of a pain to do with closing doors, arming alarms, waiting for systems to shut down i'd imagine -- so last time i did this test, i used the 'reference point' as the drain when the driver door was open (overhead lights switched off)

 

just out of curiousty have u checked to see if any other bulbs are dimmly lit? It could be your body control module that took a crap on you.

 

yup i did check that at night one day in case i missed it during the daytime.

except the hazard button, all else incl. trunk, doors, etc are off

i wasnt able to work on it for the last 2 days due to the blistering cold but hope to get a few hours in today and find the culprit.

 

I had the same problem when I bought my 2002 A4 1.8t, took it to a shop and they told me the battery cable was bad....they replaced it and I also bought a new battery all problem went away....that was two years ago.

 

interesting... any idea how they diagnosed this?

i was able to get the drain down to 300mA by disconnecting the fuses for:
- instrument lights
- air conditioning

 

Ok just found the receipt from the repair....quote from receipt found excessive resistance on positive cable which caused battery to fail as well as excessive voltage draw on fuse circuit for climatronic and instrument cluster circuit. Replace battery cable $17, battery cable terminal $16, labor $120....headache gone priceless...lol...hope this help, I gone through 3 shops to have the problem found and solve, refuse to go to Audi stealership wanted 300 to diagnose problem....hell no

 

oh sweet. thanks for digging that up. i think ill replace them just to eliminate the possibility.

also i did find something interesting. when i disconnect the instrument light fuse, this illuminates the climate control unit... but when i remove that fuse as well, the draw drops to about .25-.3 which i understand is normal.

Hmm i guess i need to get my hands on those radio removal keys and start digging... FML