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2004 V10 Battery Draining Issue

19972 Views 19 Replies 8 Participants Last post by  barnardp

Being new to modern cars I took up the challenge and purchased a 2004 V10 Touareg and hgad it for about 12 days now. The day i picked it up the main battery was flat but by using the key it started first go. I test drove it a fortnight beforehand which was alright at the time.

The previous owner seemed to know nothing about keyless entry or keyless start. always used the key. He had it at the local VW dealer and an independant auto electrian for weeks to try and fix the clock resetting and the fuel averages resetting when starting the car. VW replaced the alternator which did not seem to fix the problem.

Since obtaining the car i charged up the main battery under the seat but it was beyond holding any charge. 2 days on a 10 amp charger and a load test brought it down past 5 volts. Replaced the battery with a new one and off i went. i do a fair bit of diring during the day and leaving around 7am and getting home 10pm with intermittent trips during the day started first time every time. Doing research and reading many things over batteries and drain i did upgrade the cd navigation from firmware 0629 to 0635

I came home early on a friday around 4pm and didnt work saturday. About 2pm saturday Tried to start the car keyless and all the electronics died as it cranked over. The battery was flat again. Swapped the battery with a smaller one i had from antoher car and put the big one on charge... which load tested fine on sunday morning.

The temporary battery was flat sunday morning. i then replaced the battery again with another full one and tested the vehicle according to the tsb on battery drain.

I bought the VCDS but still awaiting to obtain schematics for this vehicle

I checked every fuse 3 times on both sides of the dash and under the bonnet. I left an inline ammeter between the battery and notcsed the current being 2.5-2.9 Amps and occasionaly it would drop to about 0.1a for half a second but then back again to 2.5-2.9..for 3-10 second intervals.

I observed some fuses showing current on and off... notably Parking sensors, Tyre Pressure monitor system, Radio and a few others.

I then also heard a clicking noise of a relay every time this happened.

Finding the offending control box I found a box labelled "Bordnetzsteuergerat" 7L6 937 049 L which seemed to click and all these things turn on and off repeatedly. Unlocking the doors and ignition and the clicking stops.

First time with the VCDS VAG-COM software the only error I found on this control module was a 00907.... battery low which I would expect with the number of battery charges and swaps I did over the weekend

Watching the inputs that I could see on the VCDS I saw nothing unusual. I learnt I had heated mirrors that was on but that’s all!

The software won’t show you what the box is doing when the ignition is off so I couldn’t monitor the inputs.

Any ideas and what else this module controls or what it listens to when sleeping?

Or something else to look for?
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As much as it says in the instructions not to ..... At the end i did end up pulling each fuse 1 at a time, and the worst i did was set off the alarm and had to start the procedure again. :p

I noticed when i did pull fuses like the Parking sensor, radio and TMPS the current did drop when the module mentioned above had its relay go into the on position but about the best i got was it was still pulling up over 1 amp when this occured. after pulling each fuse out of the ones on left and right hand dash.. this module was still clicking on and off. the power to this module must be fed from elsewhere.

I did not pull out the fuses out of the engine bay as i got a 0 current reading from all of these.. i also did not pull out the large 40 amp fuses unless i try this next.
Hi All,

The convenince module is the one making the clicking noise (relay) and continually turning things on.

Used the VCDS this evening and the kessey module showed all antennas open circuit. Reset these... and my keyless entry and the door lock buttons are working which ive never seen working since obtaining the car nearly 2 weeks ago..... which not long after stopped working again.

Found other posts on the repair thank you. i ordered the parts but not yet pulled apart the kessey as its currently my daily driver. on top of this i need to wait 10 working days for my parts to arrive. I just disconnect the battery when i get home until further service.

Im awaiting parts for the kessey to fix this before venturing further on the central electronics module that keeps turning things on and off.

The battery under the seat is only a few months old. dated march this year, totally dead and will not charge above 8 volts. AS i didnt own the car when this battery was changed i have no proof of purchase and cannot send it beck.

The battery in the back is about 2 years old and load testes fine.
Hi All,

Solved !!

I replaced the 2 Mosfet's in the Kessey module. The resistors did test fine so i left them as is. I didnt take photos as there are heaps on this and other forums on the procedure. I had it out, resoldered and in in about 30 minutes.

Another drain test on the battery and was down to 0.08A after 5 minutes sleep time which is much better than when i first started. again its still a bit over spec but my meter might not be all that accurate down to this tiny amount.

3 Days and battery is still fine. Now to fix up the rest of the electrical faults listed on the VCDS. Ive cleared all the faults after refitting battery, driving around and some came back but that will be another post.

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