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2007 Audi A3 1.9tdi Battery drain issue.

Discussion in 'A3/S3/Sportback (8P Chassis)' started by ABGogs, Sep 18, 2013.

  1. ABGogs
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    ABGogs New Member

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    Hi guys,

    I have had my A3 since June now and for the first 3 months I had no issues... because I was using it everyday, However now I am only using the car once a week or so and the problems are now very obvious.

    If the car is left for even 2 days the battery drains so low it will not start, It does however jump fine. Everything else on the car seems to be working fine, and I have checked all the obvious internal bulbs remaining on when the car is closed and locked (glove box, boot ect)

    There are some points that might be worth a note:
    1. The Hazard warning light switch is constantly illuminated (even when the car is locked and left over night) I have read online that this is not a fault but merely an indication of a fault
    2. The Radio (Concert stock head unit) does not come on when the key is inserted neither does it turn of when the key is removed (requires manual pressing the power button
    3. Some times the electric windows do not work automatically (you have to hold the switch all the way up and down) and sometimes when you close the windows fully the go back down a few inches and will not go back up.
    Everything else seems to work fine...

    This has been going on for a while now and it is really starting to annoy me, Any help would be great!

    Cheers
    Last edited: Sep 18, 2013
    #1
  2. NHN
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    NHN Modmetractor

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    Welcome to the site.

    This is the A3 section, you have an A4, so I will get it moved for you.

    Does the car have Bluetooth or/& rns-e head unit?
    #2
  3. ABGogs
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    ABGogs New Member

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    Sorry typo now edited A3.

    It came with an after market Bluetooth blackberry cradle, Which was installed between the loom and the radio, I have since removed this.

    cheers
    #3
  4. Twizzler
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    Twizzler Member

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    Measure the quiescent battery drain by removing the negative lead and inserting a multimeter on the dc current range between the terminal and the end of the chassis cable. You should measure less than 100ma with all doors etc closed. Anything above this indicates a problem which will need tracking down by isolating and measuring individual circuits after fuses have been pulled.
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  5. ABGogs
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    ABGogs New Member

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    I tried this with a current clamp around the battery negative, all doors locked and bonnet catched 'locked' With a screwdriver, Its draws 900ma all the time, Taking the fuse out for the Lamba sensor after cat reduced this to 400ma, but I think this is just a red herring.

    I was hopping the radio not comming on would indicate a common fault.

    Regards
    #5
  6. NHN
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    NHN Modmetractor

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    I would start pulling fuses until it drops considerably as above it should be allot less, I have a circuit load meter which I use in place of fuses to see what its load is when cars locked, but if the radio's an issue, I would 1st disconnect this & see what the outcome is from this.

    Also suggest when radio disconnected, charge the battery with a ctek until its got full charge & then test.
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  7. ABGogs
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    ABGogs New Member

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    Worth saying that once the above mention fuse was removed and then the 'convenience' fuse is removed it drops to about 0.09amps... but as with all common rail cars, One fuse covers many areas! I have tried this approach before
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  8. NHN
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    NHN Modmetractor

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    As I said, disconnect the radio, not remove the fuse for this circuit, then other systems shared will remain on.
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  9. ABGogs
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    ABGogs New Member

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    I will try this tomorrow, But will the hazard warning light back light remain lit to indicate an open circuit?
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  10. NHN
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    NHN Modmetractor

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    Usually indicates the car systems are not shutting down yes, hence the drain, try radio 1st as common to cause this.
    #10
  11. ABGogs
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    ABGogs New Member

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    O rite, So the radio fails and causes a drain?

    Do you know how long the car should take to go to 'sleep'

    Cheers
    #11
  12. NHN
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    NHN Modmetractor

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    5-10 minutes 7 yes radio's have been known to drain, not all just some of course.
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  13. JohnE
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    JohnE Active Member

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    There are some threads on A4 section where this was being caused by a faulty convenience module - not sure if that would apply to A3 too, but similar symptoms.

    The radio's either not connected to CAN BUS properly or the CAN BUS isn't working properly - because the ign off and illumination are controlled from CAN BUS.
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  14. ABGogs
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    ABGogs New Member

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    Is this a part that can be replaced? I have access to a scrap yard with a few a3's in it... So I could try repair by replacement.

    Cheers
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  15. JohnE
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    JohnE Active Member

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    TBH I've never done it, but I think it can be - you need to be cautious though as I think there are different versions and it doesn't look like a 10 minute job - I'd try NHN's radio route first as it'll be quicker/cheaper - I'd double check all the radio wiring - sounds like someone may have butchered it with that phone kit - could there be something still connected there?
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  16. ABGogs
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    ABGogs New Member

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    I'll try the radio method first. As far as I can see the wiring is 100% standard with no dogey wires tapped in anywhere.

    I'm just reading through the threads on the convenience module issues now.

    Cheers
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  17. ABGogs
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    ABGogs New Member

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    Update!

    I unplugged the radio, locked the car... and 1 minute later the hazard light went out! Im going to leave the car over the weekend to see if the battery stays charged, But its looking good!
    #17
  18. NHN
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    NHN Modmetractor

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    I wouldn't even bother repairing it, just find another.

    If the scrappy yields nothing, we have a concert 2+ available with pin fully working.
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  19. ABGogs
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    ABGogs New Member

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    Yeah I wasn't going to attempt a repair.

    How much do you want for this concert?

    Providing the battery stays charged this weekend I shall be after one

    Cheers
    #19
  20. NHN
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    NHN Modmetractor

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    Send me a PM when you've definitely put it down to the radio.
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  21. ABGogs
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    ABGogs New Member

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    Will do! Do you rekon a faulty head unit would also be the reason the radio wasn't comming on or off with the key?
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  22. NHN
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    NHN Modmetractor

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    Possibly, could also be a faulty ignition switch, but test battery 1st with radio out, then approach other things.
    #22

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