First post here and it's for my daughter's Polo, but I hope you'll help anyway.

Problem is that the battery goes flat if car left for 4 days or more. It has done this for months now but she uses the car daily and has "managed".

I checked the battery which gives 12.4V disconnected from everything and hasn't dropped for 48 hours. I reckon that is 75% charged and OK.

The car is pulling current when supposedly "off".

My meter shows more than 200mA but doesn't register on the 0 to 20A range. There is a hefty spark when I touch the meter probes between battery and disconnected battery feed to car. Probably more than 1 Amp.

I'm aware of alarm module, remote central locking sensor etc but I tried removing a few fuses (there seems to be 51 fuses) and haven't isolated the culprit. No car lights are on, no radio etc.

Alternator seems fine, charging at 14.6V I'm aware of alternator diode leakage. Is this likely?

Car is a 2002 Polo 1.4tdi and is one of the early 9N (latest shape) models.

It does have an aftermarket radio and I recall some nightmares I read about problems with the radio wiring but I disconnected the radio fuse and nothing changed.

Any help would be appreciated, please.

You need to wire in the ammeter and then leave car locked for 20 minutes to get the true current leakage. It takes that long for everything to go into sleep mode. You should get a reading of about 6 milliamps if everything is OK.

Radio will have two feeds, so make sure both disconnected when fault finding.

Even though I have disconnected the car battery 24 hours ago? I suppose my action of bridging battery and battery lead via the ammeter "wakes up" the modules.

I know there is more to this than I thought. I had to phone the dealer to see how to disconnect the battery without the alarm sounding. Yes, with a disconnected battery. I won't detail that here but I was surprised at the complexity.

It's pouring with rain now so I'll try tomorrow. I'll open the bonnet, lock the car and leave it 20 mins, then I'll post back.

Thanks so far.

Please help, I'm stuck now.

The battery maintained disconnected voltage at 12.4V for 72 hours. I charged it today at 6A for around 7 hours. Voltage then showing 13.1V immediately off-charge, falling back to 12.8V an hour later. I reckon the battery is OK even though it's 7 yrs old.

Problem is the parasitic drain. I cannot disconnect the factory alarm. As soon as I try to measure the leakage current I see a small spark on the meter probe and the alarm sounds even though battery disconnected. (i'm measuring +ve batt post to +ve lead to batt). Would -ve make any difference? )

How do I disable the alarm, please?

Alarm is sounding as it has it's own Ni_cad backup battery. If you do your ammeter test wiring and alarm sounds, you should be able to cancel the alarm with the key fob.

Another method, is to use a memory saver battery plugged into the cig lighter socket. Make your test connections at the main battery, then disconnect the memory saver battery. This should fool the alarm into thinking all is well.

If the car has boot area light, make sure it's going out with the tailgate shut (simply remove parcel shelf to observe the light.)

The alarm won't cancel, presumably because the car battery is disconnected. I can only cancel it by reconnecting car battery, silencing via remote and then disconnecting via key in ignition etc. I can remove battery lead again OK, but as soon as I meter test between post and lead, the flippin' alarm sounds again.

I checked that all lights go out, including the boot lamp.

I'm dubious now about the Nicad battery. I had to change several of these over the years, usually in BMW dashboards where they maintain service data.

Given that the Polo is now 7 yrs old, I'd like to change it but goodness knows where to look.

Things are quite hard now, aren't they?

Things are quite hard now, aren't they?

Bloomin' nightmare mate, hard to keep up with modern cars and all the gubbins they cram into them. My other cars a Morris 1000 Traveller, two tools, 13mm ring spanner and a hammer

Anybody want to buy a Polo TDI Sport kit?

Seriously, the car is in bits. I think I got the blighter of a drain though.

It turns out that these bee-sting aerials have a power amplifier on them. When you wire the radio up you have to ensure that the feed to that goes through the accessory switch on the ign. Ours was permanently fed.

I hope that's the end of that one.

Thanks Moggy Tech, for solidarity and your help. All I need do now is recuild everything.

Edited 3 August, 200916 yr by fatty5000
Non freedom advert

Hopefully, you have solved your problem.

The 'secret' to doing a current leakage check without setting off the alarm is to hold one meter wire to the battery post and the other to the battery cable clamp. Then remove the battery cable from the battery post whilst still holding the meter wires to the battery post and battery cable.

In this way the current is never interrupted so the alarm doesn't go off.