Mark 5 GTI battery drain issue, not the stereo.

[Paulo P]

Hi,

I have a bad battery drain on my Mark 5 GTI which is killing the battery in less than 2 weeks. At first I suspected it was the stereo and maybe someone had changed my head unit but found that it wasn't that.

With the car locked I can see this drain.



Remove fuse F3 from the engine bay



and the drain instantly drops to this



A google search suggests that fuse F3 is for the multi function on the clocks, has anyone experienced this drain before and cured it?

Thanks 

[Paulo P]

Anyone come across this?

[pudding]

It won’t be for the clocks at 20 amps!  I’ve seen another reference saying it’s for the ‘onboard power supply module’ whatever that is!

I guess with that fuse pulled, figure out what no longer works on the car, or plug in a scanner and see there’s any power supply type fault codes.

Unfortunately F3 is not mentioned at all in the handbook.

[Dogma]

How old is this battery?


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[Paulo P]

It won’t be for the clocks at 20 amps!  I’ve seen another reference saying it’s for the ‘onboard power supply module’ whatever that is!

I guess with that fuse pulled, figure out what no longer works on the car, or plug in a scanner and see there’s any power supply type fault codes.

Unfortunately F3 is not mentioned at all in the handbook.

I'll have to try that then, I was hoping that it was something that somebody had already come across. Thanks.

[Paulo P]

How old is this battery?


Sent from my iPhone using Tapatalk

The battery is about 8 months old, it previously killed a Bosch S5 in 10 months from new when it went flat unnoticed.

[Paulo P]

I've just got around to removing that fuse to see what stops working and it's the remote locking. With fuse F3 removed, the remote locking doesn't work and neither does the central locking via the drivers door lock. The central locking still works via the button inside the car though.

Has anyone got any ideas what part that could point at?

[Paulo P]

Anyone? I notice that the alarm LED is still flashing on the drivers door when I lock it manually which says to me that it's not the alarm that's causing this drain. A few years ago the alarm siren used to go off on it's own but it's not happened for years, even when the battery drains. I still wonder whether it could be linked to that?

[muff1991]

could be linked... but not certain.

I knew someone whos battery would drain and it turned out to be the boot lid wasn't shutting off the boot light when closed. wasn't a VW but anything's work a check.

[mo]

Apparently there are 2 identical relays in the engine bay fuse box that can cause battery drain if faulty.