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Discussion Starter · #1 · (Edited)
Hi, just thought I'd post my experience of my battery drain that I eventually solved.

Thought I had a faulty battery so replaced it but battery kept on draining.

Been searching for around 2 - 3 weeks now and so have read many, many posts on this subject. There seem to be lots of posts that dont have conclusions and it was difficult to find posts that related to my specific issue, standard car just with battery drain as a lot of battery drain issues seem to be due to radio upgrades. Common issues did, however, seem to be related to the Siren horn or faulty door modules. I did a scan and I had both a faulty passenger door module and the siren didn't work.

Ended up doing a parasitic drain test, following the 'old' method of putting my multimeter in series with the battery, I found this easier than the VW technical bulletin method of checking the voltage across each fuse and it didn't cause me any issues with modules waking up.

I had a drain of 97mA, the only fuse that dropped this was F3 in the engine bay.

I thought I'd ruled out the alarm by removing the fuse in the interior fuse bay so then thought it must be the Door Modules or the CCM. Unplugged all door multiplugs at the door pillars...no change, tried a replacement CCM...no change, replaced the faulty door lock module...no change!!

So the only thing I could think of was the alarm siren and that it must be powered from somewhere else and not go through the passenger compartment fuse, so I took the wheel off, removed the plastic liner, drilled out the metal box and unplugged the siren.

Current draw dropped to 5mA!

So for me it was a case of a faulty alarm siren constantly drawing power from the battery, and it draws approx 90mA.

Hope this helps someone trying to diagnose their drain issue!

Took the siren apart as i've seen replacement batteries on ebay but it's completely fried...battery acid leaked all over the circuit board! Pretty poor design!

I can live without the alarm!

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Discussion Starter · #3 ·
You should be able to get a replacement siren... make sure you get the same part number and it should be just a swap over...
I think its one of the first of this type, ending with an A, so any used siren is likely to in the same condition. Car is old now, I've coded the alarm out and also disconnected the tilt sensor, favouring battery life over the alarm
 
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