Electrical problems make me sad. Battery drain.

Pants

Pants

Pants

Soldato
Joined
18 Oct 2002
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Leicester
Hi,

I'm hoping somebody could help with an electrical drain i've got on my MK1 Octavia VRS.

When my car is locked there's a draw of 210mA which is killing the battery in two or three days. I've left it locked for at least 20 mins and the same draw is still there even after all of the systems should have shut down:



I've isolated it to this wire. When it's pulled there is no current being drawn:



That's not too helpful because I have no idea how much stuff this wire powers. So to try and narrow it down some more i've tested the individual fuses in the fuse box at the drivers door:



In that picture i've taken Fuse 14 out (3rd in, 3rd down, from the top left) as this is the only one that seems to change the current draw. When that fuse is pulled I am getting a much more respectable 50mA total draw from the battery - although even that seems a little high:



I know this fuse is interior lights (of which none are switched on), but i'm not clear on what else it's doing. To dig a little deeper I tested the current for just this fuse. This is where i'm getting really confused. This fuse only draws a small 20mA. Although the total effect on the draw from the battery is 160mA:



So i'm a bit lost on what to do next, and this is annoying the hell out of me. If this fuse box isn't using the power then what the chuff is? Am I being daft and missing another fuse box or something?

Appreciate any help!

Cheers.

Anthony.
 
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Thanks.

Looks like this could well be the central convenience unit. The only strange thing is that in my case, nothing appears to have stopped working.

I just need to figure out now if it needs replacing, or if the problem is that something is failing to send a signal to tell it to shut down.

I might check the plugs in the drivers door just in case: http://www.briskoda.net/forums...
 
Check the wiring looms that go into the front doors and the boot hinges, the wiring frays at those points and may cause a drain or fry the convenience module, although the fuse would *normally* do its job there.
 
edscdk said:
next post from op "posting from my phone, does anyone know how to open the boot of a MK1 Octavia VRS from the inside?"
Click to expand...

Thats no joke :mad:

Did it to myself once in the back of a old audi estate, couldn't get out of the back and got stuck half clambering over the back seats trying to get out of the front doors.
 
dalin80 said:
Thats no joke :mad:

Did it to myself once in the back of a old audi estate, couldn't get out of the back and got stuck half clambering over the back seats trying to get out of the front doors.
Click to expand...

:D thats just made my morning

Thanks :)

I hate electrical drain issues - pain in the rear to track down.
 
I'll update my saga here, posting it on briskoda too...

Just checked the plug in the drivers door. All looks OK: (followed the first part of this great guide http://www.briskoda.net/forums... )




Also pulling this plug out takes the total consumption from 180mA to 140mA:




Damn, I was hoping it would be this plug so I could just WD40 it! More searching.
 
After more interior removal I've got to the Central Convenience Unit (I think).

When I take the centre-most plug out of this the draw from the battery drops right down to 10mA. Sweet.




The next thing is, how do I work out if this control unit is faulty, or if it's something connected to it?
 
They seem to go for £100 on e-bay. I'll ask at some breakers too.

I've opened it up and there are no burnt solder joint etc which is annoying as I could have fixed that!

I'm just not sure how to check if this thing is really faulty or not.
 
See if anyone on the briskoda would be willing to try your module in their car, or their module in your car?
 
Just bought a used CCU from the ebay. So I'll see how that goes in a few days. Just ran a fault diagnostic on the unit in VCDS Lite and I'm getting this:



Not very helpful because I don't know if there are really no faults or if it's a DTC / comm error. Sigh.

On an unrelated note my car failed it's MOT due to a leaky Weitec rear damper that was fitted under a year ago. I think this one had a manufacturing defect:



Bad times. :(
 
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Can I ask a really dumb question.. how do you check with a multimeter how much current is being drawn? I've got a similar problem with my Type-R, battery drained in 2-3 days. I've got a multimeter but don't really know how to use it :( Do I use put it across the two poles of the battery?

If it's not too much trouble can you provide a basic "for dummies" guide on what I should set the multimeter dial too, and where I should measure?
 
The first thing is to put the plugs into the right place. One into the COM and one into the 10A DC port. Switch the multimeter to the 10A setting.

Don't put the multimeter across the battery terminal when it's setup to measure current as it will blow the 10A fuse (or melt the rails if it's un-fused).

You need to break the circuit you are testing and put the multimeter in between so the current runs through it (in series basically). I'd start by testing total draw from the negative battery terminal to the main negative wire, then pull some fuses and see what happens.

You are looking for no more than a 50mA draw for a healthy car (that shows as 0.05 on the 10A setting).

One thing I'd be sure to do is make sure the car thinks it has been locked for at least 15 mins so all of the computers shut down (even if the doors / bonnet is open). This might mean using a screwdriver to move the door catch etc.

There are some good guides on youtube under parasitic draw or parasitic drain.
 
Some multi meters come with a 'amp-clamp' which allows testing with no risk or interruption of circuits but aren't always 100% reliable.
 
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