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VAG-COM Error 01598 - Drive Battery Voltage - Implausibe Signal

Discussion in 'VAG-COM & Diagnostics' started by Pabs, Aug 19, 2009.

  1. Pabs

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    Hey Folks,

    Got the following error on VAG-COM:

    Address 09 -------------------------------------------------------
    Controller: 6Q1 937 049 D
    Component: 0000 BN-SG. 1S34
    Coding: 16396
    Shop #: WSC 06402
    1 Faults Found:
    01598 - Drive Battery Voltage
    27-00 - Implausible Signal


    I've cleared the code, but it doesn't seem to go away. It still shows once cleared.

    Car starts fine, no issues there. Haven't chucked a meter across the battery yet - but in the meantime, does anyone have any ideas?

    It's not the usual LOW signal, and I've searched on here, with no real answers.
    Cheers
     
  2. Big_daddy

    Big_daddy Going going gone.....

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    Could be a loose earth some were.
     
  3. Pabs

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    yeh, i thought that might be possible - Not sure where to look though as Engine doesn't seem to have a problem starting - radio/dash cluster etc all seem ok.

    Wonder if there is an easy way to find all the earth connections in the car..?!? lol
     
  4. meltonlad

    meltonlad Active Member

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    01598 - Drive Battery Voltage
    01598 - Drive Battery Voltage: Signal to Low
    Possible Symptoms
    Engine not starting
    Possible Causes
    Battery low
    Battery faulty
    Possible Solutions
    Charge Battery
    Check/Replace Battery

    hope this may help you ?
     
  5. Pabs

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    No mate, sorry, doesn't help. Already searched etc and come up with that - but that is "Signal Too Low" error, not Implasible Signal.

    My Implausible signal is also not intermittent - therefore as suggested above it could be an earth that's not connected properly.. whatever it is it's a permanent issue.
     
  6. Big_daddy

    Big_daddy Going going gone.....

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    well check the earth for the ecu (if it has one).
     
  7. Pabs

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    FYI to anyone interested, or in the future:

    I found the cause of this problem - on the negative terminal of the battery clamp, there is, or should be, a single black wire (very small gauge) that connects to the wiring harness below, which then runs to the ECU on the firewall.

    If it's not connected, broken, or loose, it'll cause this error in VAG-COM.

    Mine I found, was snapped clean off the crimped connector, and hanging loose down in the engine bay. After a bit of messing around, and rerouting the cable, I've reconnected it and now managed to clear the error code. :)

    Hope this helps!
     
  8. BeartheBruce

    BeartheBruce Ross-Tech, LLC

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    Makes total sense - that wire is the battery sensing wire. The ECU is measuring the voltage at the battery terminal. If the wire is broken as you said, the measured value would be floating all over the place - picking up "noise" from the engine bay. The electronics didn't see a value in range so it reported an "Implausible" signal.

    Nice catch on the broken wire.
     
  9. Pabs

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    Brill - thanks for the confirmation!!! :)

    Is that ALL this cable does? It doesn't have any other impact?
    Thx
     
  10. BeartheBruce

    BeartheBruce Ross-Tech, LLC

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    I think the ECU uses that wire to determine voltage regulation. While I do not know for a fact, I would venture a guess that the battery voltage regulation and the output of the alternator are controlled by the feedback from this wire. I would have to look at the wiring diagrams and so on to be sure I am correct but I would think that voltage regulation would be the primary function of this wire. Remember - I said "I think".
     
  11. Pabs

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    ok thanks.

    The reason I ask, is because the car is currently suffering from some boost fluctuations, which I believe is being caused by the N75 valve. I was thinking along the lines of the ECU controlling this, but adjustments being made incorrectly due to an unknown reference 0v or something.

    All the above is just guessing - and I suppose next time I drive the car I'll see if there is any difference. Failing that, it'll be valve swap.
     
  12. BeartheBruce

    BeartheBruce Ross-Tech, LLC

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    I would not expect boost issues to be related to this wire and the previous fault. That's not to say that it isn't but .....

    Who knows, maybe the engineers decided that if they don't know the battery voltage, they'll take away performance. Anything is possible!
     
  13. Pabs

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    thanks. I was simply guessing/hoping. lol
    I'm not losing performance, I don't think - the car has LOADS of power! But the N75 just doesn't seem to know when to open/close properly, so it's probably totally stuffed.

    Thx!
     
  14. LeonCR

    LeonCR Active Member

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  15. christhemann

    christhemann Active Member

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    Hi Pabs,

    I'm new to the forum, but I saw your thread as I have a very similar problem but on a different car. Mines a Seat Leon MK2 2009 1.9TDI.
    I don't suppose you have a photo of the wire in question?
    I know it's a long time ago, you might not remember.

    Maybe someone else could answer if my car is supposed to also have this wire because try as I might, I can't find it anywhere! There are no extra terminals on the negative for the battery, only the clamp.

    Cheers,
    Chris
     
    #15 christhemann, Mar 8, 2015
    Last edited: Mar 8, 2015
  16. gaz1211

    gaz1211 cupra_gaz

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    Hi I have this issue only the wire that's spoken about is fine all intact but I do have an issue with head lights were when power is drawn say I turn the steering wheel the lights dim any one had this it's just had new battery ?
     
  17. bradfr

    bradfr Active Member

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    I have this problem on a polo. Battery, PAS pump and alternator have been changed and I've checked the wires that have been mentioned but it's still not any better. Does anyone have any ideas?

    Thanks
     

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