Scirocco Central

Hi guys,

Quick caveat, I know nothing about cars, so I apologise in advance if I butcher any of this

My Scirocco (2013 GT 2.0 TDI 140/150) battery has a slow drain. Initially I thought it maybe due to the cold weather, but when it happened for a second time a week later I asked an auto electrician to take a look (both times when I hadn’t drive for a couple of days - most days I do a 60 mile round trip).
He told me it was a very slow drain, disconnected every fuse individually from both fuse boxes but was unable to locate the drain, so ruled them out.
He then advised me to get it into a garage to have the alarm siren checked (located in the front driver side wing) and if no drain found to have the battery regulation unit checked for the drain. He didn’t know where this was located on the Scirocco, so if anyone’s knows, it would be good to know.
Any advice would be much appreciated. For example, given the fuses have been ruled out, how likely is it the drain will be coming from the two suggested parts? Could it be coming from many other places given all fuses have been ruled out?

Voltage regulator is behind the glovebox compartment.

Thanks mate, appreciate that.

Are you 100% sure it is a voltage drain? All modern cars use a small amount of power when not running. A car will show a small voltage use when first switched off for a few minutes until it “goes to sleep” for want of better words, this can be anywhere between 2-3 mins up to around 10 mins depending on model so may show as a drain until this happens.
Did the auto electric actually test the battery as that would have been my first thought especially at this time of year.

Hey Kris,
Yes, checked both the battery and alternator, both all good, also had both changed last year.
If I leave it for 2 days, it dies. The auto electrician said it’s a very small drain. I think I’m going to book in with VW, as it’s a bit of a needle in a haystack.
I forgot to mention, incase maybe related but the stop/start on the car had never worked since I bought it about 3.5 years ago, dunno could be linked
Any further thoughts or suggestions would be welcomed

Have also checked the bolted fuses that are mounted on thé front of the engine bay fusebox? SA1 till SA6?

https://www.dropbox.com/sh/nerw5cwkh9ug ... nwards.pdf

A very small battery drain is normal as things are used electrically when the car is parked up.
May I ask what battery you have fitted to the car? (I’m terms of cca or a/h is the car used often and have you given the battery a good charge?
This time of year in particular, we use alot more power when driving like lights, heater & blowers heated seats etc.
If you are only doing small journeys the battery isn’t getting a good charge so while your battery and alternator may well be okay it’s just not getting a good enough charge.
If you have a battery charger it may be worth removing it and giving it a good charge. If it is low on power (a battery may well show over 12v but still not have anywhere near enough power to start the engine particularly a diesel as it takes one hell of a lot of power to crank the engine.

VWs up to a certain year suffer from can gateway caused battery drain after swapping stereos to aftermarket ones. Usually a can gateway upgrade cures this. Not saying yours has that issue but disconnect the head unit for a couple of days to see if the drain stops.
Had an issue with my old Transporter. Fitted an Xtrons head unit and two days it was flat.
I confirmed it by placing my multimeter on amps range with the leads in the correct place (different when reading amps), I was getting something like 0.4A drain then once the radio fuse was removed it dropped to something like 0.15A (please don’t quote these figures, it was a long time ago and the memory is crap) but it was nirtuceably different with the fuse removed. You will need your meter in series with the battery cable which has been removed from the battery terminal.
Got a head unit exchange which cured it.
Don’t try and crank the car whilst the meter is connected or it’ll likely blow it as cranking amps can be extremely high.

Hi all Rocco owners... I'm back after over 10yrs without any concerns with my 2010 R bought in 2013.

For 4yrs now I have had issues relating to EPC Light coming on with a steady slow draining Battery.
Having solved 1 issue with a failed diaphragm on the 1st PCV (it whistled after shutdowns so you know it), I now only get the Battery Light Warning when in the Winter. This is has never been an issue in any other Season. I tried a new Battery 4yrs ago but they did not use the same 27 Battery and the standard one they used was for othe non R Models. This went dead in Winter like the old stock one which lasted 6yrs of my Short Trip Usage 50miles per Week but gets left at the Airport in Winter for 1 month!

I then cahnged battery to the proper 27 model and this has now drained in Winter for the past 3yrs. Although the problem was not always clear that it was Battery, Alernator or other and I thought it was really the failed PCV which always caused it bad starts as after 30secs it would always start no problem albeit with EPC for the next 10mins of running it. I even timed that EPC Warning at standstill and it sure is 10mins Timer to clear. Whilst with EPC fault it can run RICH but it never did show low mpg and was still always 28mpg for10min runs.

I also had a Fuel Cap Activator issue which would not LOCK but fixed this after seeing on YT needing to keep pressing UNLOCK on the FOB whilst repeat pressing the lock spindle until it frees up. It also needed WD40 to clean the spindle to allow it to turn. This very likely has been a constant DRAW and could be the Slow Drain I noticed.

Then I noticed I also have not ever heard my Alarm Siren go off ever! It made me wonder when it was on a Tow Truck and the Driver had zero knowledge of any Tow Mode! At the time I could not think clearly as it was being rushed off to the body shop by 3rd Party Insurer causing Wing damage by reversing into in a Carpark. It has a TOW MODE to cancel Interior Sensors by the Drivers Side! It's a 1 use then Lock Doors then resets again when opened. SO... my alarm (if it was functioning) would have gone off constantly for 1hour to the Bodyshop! That will (if it was working) either have burnt out the Siren or just the Fuse, OR drained the Alarm's own Battery.

I checked the Interior Alarm Sensors and it sets off the Indicators but the Fuel Cap issue had me thinking...

1. When you buy a new Siren it must have it's own Battery Charged (new devices well could be already but compare this to how PIR sensors also need charged before use and anything which uses re-chargable batteries). A post I seen for a Golf stated to leave the Car Running for 1 Week until doing anything else (e.g. removing Car Battery to re-charge) to allow the Alarm Battery a chance to charge fully.

2. When installing a New Alarm it then must be Programmed into VCDS and the method is to go through 9 Tests with No.8 being the Alarm (others are Tailgate Lock etc.)

SO the Siren may NOT have been broken but it may just need as any other NEW ALARM needs to work again.
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NEXT about charging a BATTERY because you DO NEED a almost fully charged one to then test for any PARASISTIC DRAIN...
1. Either give it a Run for 30mins then test with it SWITCHED OFF and be sure it reads 12.6v (12.05v = 50% only) with Volt Meter set on 20V or take it to KwikFit or other for a Battery Health Check & Load Test. Else remove it, use a REPAIR function if available on your Charger to remove SULPHATES (mine is a SIGMA 5 for 3hrs), then Charge it, and then charge again if this only lasts 4hrs each time. Some run all night and would not be long enough to be overcharged.

2. Test your AMPS set to 10A in Series on the Negative (safer) after leaving it sit for 30mins (*is there a more precise time?) for SLEEP MODE with Bonnet already popped ready to lift open (*does this set off an Open Sensor? - nothing on my MFD - only alarm is if travelling 60mph with it open)

3. Should be less than 0.5A else it has a DRAIN. If not in SLEEP MODE by opening any Door or Unlucking to pop the bonnet then this will show more current than you are searching for as a false result.

4. Test Engine & Interior Fuses by Volt Meter set to Millivolts DC and conect both ends to end of each fuse and should show 0V. Any which have Volts are the circuit loop to explore the root cause. Check the Fuse Diagram which one that is for.

5. Pulling that FUSE out will also show a reduction of AMPS at the Battery you did firstly. This way you know if there is more than 1 fuse fault to find and to comapre known Amps drop for each rated FUSE used on that circuit to figure if it has dropped succiently to reflect a Base Reading.