Battery drain still happening... Completely stumped :( **UPDATE**

[MJ]

You've got an alarm horn fault, That has an internal battery that when faulty will do nothing other than draw current from the battery until it's specified charge level is reached, with a dead battery cell it never will so it just flattens the main battery. Get the o/s/f arch liner off and disconnect it and see if it changes behaviour over the next week.

[Eddie-NL]

No

only other faults that were there were the items that were removed (No Inclination sensor, No radio, No interior monitoring) which I refitted prior to testing

[Eddie-NL]

You've got an alarm horn fault, That has an internal battery that when faulty will do nothing other than draw current from the battery until it's specified charge level is reached, with a dead battery cell it never will so it just flattens the main battery. Get the o/s/f arch liner off and disconnect it and see if it changes behaviour over the next week.

All circuits were tested including this one, nothing

Also this is a very common fault on the Mk5 and other Vag cars

[MJ]

I'm well aware of the alarm horn issues. I've had it on my own car but Disconnecting it has got to be worth a try For the OPs sake. Unless you mean that fault was induced when you tested the circuit and wasn't there before?

[Eddie-NL]

It is worth it, just not easy for someone if they don't have the right tools to do it

The circuit for the horn, motion sensors, inclination sensor didn't give a reading so was not drawing

[Craigh1983]

I'm well aware of the alarm horn issues. I've had it on my own car but Disconnecting it has got to be worth a try For the OPs sake. Unless you mean that fault was induced when you tested the circuit and wasn't there before?

My alarm has never worked since the day I bought the car 2 years ago and the battery hasn't drained up until a couple of months back.

To be honest I just can't be arsed with all this now lol The car has been a bad one since the day I got it. problem after problem and I can't waste anymore time and energy and money on it. I may charge the battery up and part exchange it if I can't get to the bottom of this easily. I have no knowledge of all this kinda stuff so being able to get to the bottom of the problem is going to be very difficult :(

It's not even like I have a mate who is just around the corner who can spend the hours it needs on it.

Completely at a loss!

[dan930]

I've also had this problem so brought a cheap 027 lion battery from europarts,all seems good for a month until it started to get colder during dec-jan...can't start the car if I didn't use it for 36hours...brought a Bosch s5 & touchwood all is ok for now
Here is the info i copied from the europarts page
Detailed Product Information
The Bosch S5 Battery range is ideal for vehicles with higher than normal electrical drains. Most modern vehicles are now fitted with heated seats, windscreens and other electrical drains. The Bosch S5 car battery is able to offer up to 30% more power compared to the factory fitted battery, Because of this is also have up to 30% longer service life. All Bosch S5 batteries are sealed and maintance free for maximum peace of mind
Amp Hours: (Ah): 74AhCold Cranking Amp: (CCA): 750CCALength: 278mmWidth: 175mmHeight: 175mm

[Craigh1983]

I can't see it being the battery to be honest mate. Drive around 100 miles over the weekend. Parked car up Sunday night and Tuesday morning completely flat. I would have thought the s5 can hold charge for more than 2 days.

[MJ]

I've seen door control modules cause problems like this when one of the can bus wires brakes but they usually log a single wire fault. Same time span for the battery to go flat too.

[Craigh1983]

I've seen door control modules cause problems like this when one of the can bus wires brakes but they usually log a single wire fault. Same time span for the battery to go flat too.

John from the forum said he thinks it could be a door module or boot switch. How am I gonna tell it's that though? Do I just keep taking a voltage reading from the fuses every now n then to see if something has woken up?

[MJ]

Current drain test from the battery terminal, check their sleep status using live data on VCDS/vas or scope the wires, if there's anything other than a flat line then they're still drawing current.

[Eddie-NL]

checking via battery terminal is not the way to check on a CAN system as it doesn't pin point where the issue is

[Craigh1983]

checking via battery terminal is not the way to check on a CAN system as it doesn't pin point where the issue is

Well i'm going to try and test each fuse like you did Ed and see if I get anything from that. If not.. I'm getting rid of the car.

[MJ]

checking via battery terminal is not the way to check on a CAN system as it doesn't pin point where the issue is

No but it will reveal if there's a voltage draw like on and 12v stand alone. It might not show what it at fault but it will prove a drain exists, hence the other two parts of the response which will pinpoint the issue.

What is the amp draw at the battery by the way?

[ryanpp]

Hey,

I've had this issue too, and decided yesterday to pay VW £300 odd to do it. Just signed up to answer this :)

There were several reasons as to the drain:

- Alarm horn fault
- Aftermarket stereo - This was coded out of the ECU today, as when no VW stereo is present, the ECU CONSTANTLY searches for one.
- Auxiliary heater - This is the issue they are currently fixing, they believe there was a resistance to ground across something on the heater, hence the drain.

I'll update if I hear any more.