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Please help (strange battery drain)

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by mrlinderley, Nov 19, 2008.

  1. mrlinderley
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    mrlinderley New Member

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    Hi everyone
    I have a strange problem with my 2001 2.5 TDI Quattro A4. After 2 days of my car being stood the battery is flat. I ve noticed that when I leave the car either locked or unlocked for about a minute the backlight for the hazard warning light goes on and off about every 15 secs as does the light on the switch for locking the rear windows. I ve used an ammeter to test the current draw and it reads 1 amp when the lights come on and zero when off so this is obviously the problem. I ve removed the bulbs and the draw is still the same so something else is being activated. I ve gone through all the fuses in side panel and none of them make any difference (is there another fuse box somewhere?) I ve cleaned all the contacts in the electrical box under the passenger side footwell and it seems like there is no water ingress. I don’t know what else to check, could it be a faulty relay (clicking can be heard in the car as the lights go on and off) and if so which one controls these 2 items. I really hope someone can help as I need to sell it asap. Sorry for the long message.
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  2. evilscotsman
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    evilscotsman Space Cowboy

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    I think the hazard backlight is controlled by the ecu, and stays on for about 30 secs on mine after the doors are closed or the car is locked, then fades out as the led starts to flash on the door for the immob. Maybe the ecu is faulty since a relay cant close by itself inless its told to by a switch or ecu output for instance. I hope it is something simple but could be the ecu or the immob trying to tell you something.

    What about getting it scanned for fault codes?

    Anyway the battery should be say a 60 or 70ah one, which means 70A for 1 hour, or 1A for 70 hours etc, that level of current shouldnt kill it, unless the battery is weak anyway. I had to replace mine recently for dying out of the blue each day for 3 days, it was making the car act screwy too, putting different errors on the DIS from wobbly voltage to the ecu I think.
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  3. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    Yes, I agree with the scotsman, a battery on its way out can cause all sorts of issues with the electrics. Even good car batteries only last 5-6 years so I would start there (unless the battery is fairly new) as it's a cheap easy fix at about £70 for a Bosch Silvertop from GSF. At least it will eliminate the battery as the possible cuplrit. And remember a 60 ampere/hour battery will only provide 1amp for 60 hours when brand new. As soon as it's fitted its performance will start to degrade, so a 2 year old battery will not provide 60ah anymore probably 40 or even 30.
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    remember that 70ah rating is till the battery is dead. A 1A draw for 48hours could well have drained it enough so that it cant start the engine...

    i would check things like the boot light are actually turning off, a broken boot switch could mean that the light stays on and kills the battery.

    Failing that, check the central locking/comfort ecu isnt soaking wet.
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  5. mrlinderley
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    mrlinderley New Member

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    Thanks for the replies

    The battery is only 6 months old so I don't think its that. I had a look at the comfort module (under passenger side left on mine unless i found the wrong thing) and cleaned all the contacts and there was no sign of water either.

    My thoughts now are that it could be the alarm or immoboliser. The handbook states that the indicators should flash when i set the alarm with the remote but they don't. Also the led on the door is meant to flash rapidly for 30 secs then flash slowly. mine flashes slowly from the start but when the hazard backlight comes on inside the led flashes again. I could be way off the mark here though because the problem also happens when i havn't locked the car and therefore the alarm isn't armed.

    Is there anyway or disabling the alarm and immoboliser to test this theory?(fuse etc)

    One more thing, as hard as i try i can't set the alarm off. Is there a sure way of doing this just to see if it is actually armed?
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  6. mrlinderley
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    mrlinderley New Member

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    One other thing I ve noticed is that i can't enable the 2 switches in the drivers doors (ultrasonic and tow away) The leds are on. Any clues anyone, could it still be a convience module problem?
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  7. evilscotsman
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    evilscotsman Space Cowboy

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    it could be an immob fault, not unheard of mate. You should try to get it scanned for codes.
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  8. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    you tried scanning the alarm/immo module itself to see if its logged any fault codes?
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  9. mrlinderley
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    mrlinderley New Member

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    Thanks
    Went to dealers today and they wanted 75 quid just to scan car, so i ve borrowed a elm327 and a obdII lead. I ve also got vagcom 303.1 software. Should i be able to scan the car with this equipment or is the software too old?
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  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    give it a try n see if it works, but it might be too old to read the CAN modules if the car uses it.
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  11. mrlinderley
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    mrlinderley New Member

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    The vagcom version is actually 409.1.
    I ve installed the driver for the elm327 and installed vagcom. I ve changed the com ports to com2 but when i do a test i get:

    port ok
    interface not found

    The ignition is on
    Any ideas?
    #11
  12. NHN
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    NHN Modmetractor

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    I would check the siren fella as these cause all kinds of things on the system, I had a tilt sensor go on my 8P & feck me did it mess my locking system up, one minute work, next minute wouldnt, it basically messed up the conveneince module signals on the canbus so until it was disconnected or replaced it would mess about, so check tilt, siren, convenience module, all these, I also had the all to familiar siren fault on the 8L, this caused few issues aswell.
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  13. evilscotsman
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    evilscotsman Space Cowboy

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    its looking for a genuine ross tech interface but maybe yours isnt compatible. Anyhoo The elm software is nothing to do with vag com and should be uninstalled before attempting to use vag com. its probably hogging the port that you need for vag 409

    A pure elm interface wont work with vag 409, only maybe the 300 series versions and even then not completely. Ditch elm, use obdii and vag 409 only.
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  14. 1210tech
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    1210tech Four Ring Fanatic

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    i had a similar problem with mine, kept going to use the car only to find the battery was flat. after a lot of researching and checking different things i pinned it down to the convenience module, bought a replacement and fitted it and problem solved.

    the faults i had were the red hazard warning light triangle on the dash board stayed on all the time, the interior lights would flash on/off with the engine running and any door open and then the alarm siren started going off all the time

    i would say that your faults are from the convenience module being faulty
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  15. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    is the interface actually using com2?

    I would pick yourself up a lead from ebay and give it a go with that.

    And as the previous chap said, my moneys on the convenience module.
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  16. mrlinderley
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    mrlinderley New Member

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    Took car to audi sport in great harwood lancashire jamie did an excellent job and got it all sorted. It turned out to be the steering column ecu. £250 for part and labour costs. Result!!!!!!
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