Hello peeps. New member here. My lady has an 02 Polo 1.4 auto. No upgrades, No bolt on go faster stuff. Just a standard Polo. The battery gradually discharges over a period of a few days if not being used. I've done the standard checks with an ammeter and pulled each fuse in turn. The only one that reduces the flow is the mini 5 amp fuse for the engine management. Also, the car doesn't 'go to sleep' when locked up. The LED mileage display remains on as does the clock.  I have noticed that the wipers jerk when that fuse is put back in. Does anyone have an remedy for this? If so, it would be much appreciated as I'm doing all the driving in my Passat at the moment. If anyone can help, please reply or get me on timmoy1@gmail.com

Total long shot to start with. Does it have the standard radio in still, or has it been changed?

 

How much drain are you getting with and without the ECU fuse in?

Hello Yeti. Thanks for the reply. The radio is a standard factory fit. The drain witout the fuse is 0.02A and with it fitted it's 0.12A 

Have a look at this

It might be the drain is via the alternator, if that proves to OK have a look at this  vw.tb.27-07-11 Battery Discharged Diagnosis for Static Current Draw.pdf

Thank you Nige. I'll get onto that ASAP. I did think it might be the diode pack in the rectifier/regulator but as it's a bit tricky to get to, so put out the feelers for help on here. I'll post back when I've done the checks. Many thanks. 

0.12A doesn't seem excessive to me at all, you should be able to leave the car stood for a week without issue with that sort of drain and still start it fine. I'm more inclined to think either the battery isn't getting charged properly, or it's time for a new battery. 

 

I know on the diesels the electrical load sensing wire is prone to breaking, not sure if it's the same on the petrols. Have a look behind the front valance, below the radiator, and see if there's one or two cables running across to the alternator, these can break down around a terminal that's behind the valance, about a third of the way across from the passenger side.  This stops the alternator delivering enough power to charge the battery and the car slowly runs out of electricity when in use (been there, done that). 

The voltage ate the battery with the engine running is 14.4 and the battery is brand new.  If she leaves the car for a week, the battery is dead. No interior lights on or other consumers.  Tailgate shut securely. i'll check those cables asap. thank you for your suggestions. I'll post what I discover. Regards, Tim. 

Just checked the drain again and the draw is 1.98A with no consumers. my next step will be to remove the rectifier/regulator brushes from the back of the alternator. It's been suggested that the diodes may have become faulty allowing a bleed through the alternator.

If anyone can tell me how to go about removing this item, I'd be most grateful. i.e. is there a way to do it without removing the alternator? I can't even get my hand down the front between the top plastic engine cover and the front grill. Regards, Tim.  

You can disconnect the alternator feed from the system at the fuseboard on the top of the battery, it's the thick Black cable going to the first of the "flat link" fuses (110amp) with that disconnected see if your current drain goes, if it does then you know it is the alternator.

 

The plastic cover on the engine just pulls off and with that removed you can get down to the alternator. So you could remove the supply cable from there, (15Nm)

Thank you Nige. I'll be trying that asap. Regards, Tim. 

Well, I've disconnected fuse one and it mad no difference. Fuse two however, did. Drain was almost nothing with it disconnected. I don't know what that cable supplies. I suspect this is not going to be an inexpensive fix. 

That cable supplies the fusebox inside the car, Behind the dash there is a relay panel as in this picture

Try pulling the relay in the #11 position should have a #18 stencilled on the relay, and see if this stops the drain

 

Ok, Thanks Nige. Looks like my next job is pulling relays. Oh what fun. I'll let you know what I discover. Regards, Tim. 

That relay is the X contact relief, so in theory it should drop out when you switch the ignition OFF but they have been known to fail in the energised position, so giving power to items that shouldn't be powered with the ignition OFF

 

Forgot to mention, that picture of the relay panel is from a LHD so yours might be a mirror image but look for that #18 on the relay case :)

Good morning Nige. I have pulled this relay (number 11, stenciled 18) and it's made no difference. The drain is still 1.9A. My lady is rapidly losing all belief that I am a superhero and I'm at a total loss as to what proceed with next. A VW dealer will charge a kidney, my first born and my house in payment. Any other suggestions will be greatly appreciated and investigated. Regards, Tim.   

The other things that are supplied from that #2 fuse are, the headlight main switch, 12v socket in the boot, and fuses 27 Dash, 28 interior lights, 29 Climatic/climatronic, diagnostic socket & telephone, 30 onboard Supply control unit & shift lock, 46 front wipers, 47 HRW, 48 indicators, 49 ciggy lighter & 52 headlight wash & horn.

Also try fuse 10 that's the "S" contact supply, it supplies power only when the key is in the ignition

Thanks Nige.  I'll start checking them one by one.  When I do find the cause, you'll be the second one to know. Thanks again. Regards, Tim. 

I took a photo of the fuse panel and pulled all those you mentioned Nige. and the draw was down to 100mA Then, I replaced each one in turn, monitoring the amperage. When I replaced number 27 Dash, it rose to 1.9A. So, I've left that one out for now and it doesn't seem to affect any other function. Now all I have to do is find out what the problem is with the dash. Again, many thanks for your help with this. It's become rather a mission of mine to rectify this problem, and to get some brownie points from my lady. 

Regards. Tim. 

Did you try fuse 10 as I added that after you probably read the post? as this tells the system the key is in the ignition and wakes up the CANbus system including the dash panel.

 

Fuse 27 goes to the dash panel on pin 7 of the Black plug it's a Red/Yellow 0.5mm wire

Didn't do that bit Nige. I'll get onto that tomorrow.  I'll let you know. Thanks again. Regards, Tim. 

Hello Nige. I've tried pulling fuse 10 and that made no difference. Fuse 27 seems to be the culprit. The car works fine with that fuse pulled and the only thing is, that the seat belt light is on on the dash.  My lady was so pleased to go for a drive without fear of draining the battery when she left it overnight. Now all I have to do is find out where that drain is on the dash. Again, many thanks for all your help Nige. Regards, Tim. 

I would of thought the supply was just for the memory functions for the likes of the clock ?

But that wouldn't pull nearly 2 amps, surely? Unless there is component fault allowing drain through a resistor maybe? 

No should only be milliamps,  On the 2005 models that fuse also powers the steering angle sensor, only if it has ESP (electronic stability program) but as yours is 2002 it's not applicable

Just a thought Nige. Could the fault lie with the seat belt warning circuit? i.e., the plugs under the seat or the switches in the seat belt retainer? I only say this because the seatbelt light is on and if I put the fuse back in, it goes out but with 1.9A drain.