Battery Drain Fuse 29

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TractorTel
New
Posts: 2
Joined: Fri Mar 05, 2021 4:49 pm
Drives: 2003 1.2 petrol 9N
Location: Cambridgeshire

Battery Drain Fuse 29

Post by TractorTel »

Hello

My daughters first car 2003 polo 9N 1.2 petrol.
The battery is draining overnight.
I’ve gone through previous posts on here and followed the route taking one fuse out at a time. Fuse 29 seems to be the parasitic draw. This fuse is for Air Con, data link and telephone. The car doesn’t have a telephone and doesn’t have air con. It does have a data link. The starting of the drain roughly coincides with when I used an OBD2 scanner on the data port to read codes. No codes found just wanted to check all was ok. Could using this device cause a problem with the circuit and is subsequently causing the drain?

I though maybe I didn’t exit the OBD2 menu correctly when unplugging so this evening I plugged it in again, searched for codes (no codes found again) and made sure I exited the OBD2 correctly. Fingers crossed this may have something to do with the drain. Maybe the car thinks the device was still plugged in. I’ll check the drain again tomorrow morning.

Could there be other issues relating to fuse 29?

Thanks
Johntheo1
Bronze Member
Posts: 138
Joined: Mon Jan 11, 2021 8:52 am
Drives: 2018 MK10 AW1
Location: Cork

Re: Battery Drain Fuse 29

Post by Johntheo1 »

There is one of these models in my family from new (2005) and it had/has twice the parasitic loss of other VWs, it draws 90ma v/vs 40/45ma on the others
but nothing remotely that would drain the battery overnight, it was often left at the airport for 10/12 days and the original battery lasted 13 years.
I can't recall if it was this car or a Bora that used to draw 2A with the doors unlocked which didn't matter if the car was locked overnight.
I check the parasitic loss on mine by disconnecting the negative lead and then connecting a multimeter switched to DC amps in series with one lead (+) on the earth strap and the other on the battery negative post and then wait a few minutes for the ECU to go to sleep. This car doesn't have AC either.
The data port should have nothing to do with the battery drain, I regularly plug my VCDS into it.
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