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VAG-COM ECU connection problem

Discussion in 'A3/S3 Forum (8L Chassis)' started by racc, Jan 30, 2008.

  1. racc
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    racc New Member

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    [Jan 30, 2008]
    My problem is VAG-COM can't contact ECU of my A3 1.8 (1996). Connection to ABS, airbags, central lock and meter panel (probably that, it was some time ago I last tried this) modules seemed to work. I changed connection parameters, pretty randomly though, but that didn't help. No any kind of signs of life from ECU.

    Any ideas how should I start debugging this? I've got Haynes' manual but wiring diagrams in it don't seem especially complete concerning ECU.

    Car is in running condition. It has only slight problems with starting occasionally, so in theory I could take it to Audi service. However, as I'm anyway pouring most of my money into this car (I'm a student :wacko:), it would be excellent if this could be repaired at home garage.
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  3. steve1975l
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    steve1975l Member

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    [Jan 30, 2008]
    Is it a genuine lead or from the bay?
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  4. FactionOne
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    FactionOne Administrator Staff Member Administrator

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    [Jan 30, 2008]
    As steve has alluded to already, this is the type of area that can differentiate between an eBay lead and a genuine Ross Tech one.

    On some ECUs there can be slight communication timing variations which make a lot of the leads found on eBay fall-over.

    Do you get any error messages at all?

    I had a lead from eBay a while ago and I was driving a '98 A3 at the time; everything seemed to work pretty well. I got a 2x2 port adapter for older cars for it as my father was driving a late-model Audi 100 then, and I had similar issues to you. It would connect to most of the (few) modules on his car but it never once managed to open the Engine module because of communication issues.

    As soon as I bought a genuine Ross Tech HEX-USB+CAN it worked first time, every time.

    ...So, if your lead is from eBay it might well be that it's just not going to work properly with your particular ECU. If you have a genuine Ross Tech interface it may be worth contacting them directly for support - either at their site or in the VAG-COM forum here ( http://www.audi-sport.net/vb/forumdisplay.php?f=27 ). I guess it would also be helpful if you could try to connect to it with a completely different interface (genuine or otherwise) to help rule out any issue with the controller itself (but this is probably quite unlikely).

    Regards,

    Rob.
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  5. racc
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    racc New Member

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    [Jan 30, 2008]
    Indeed, I forgot to mention about the adapter.
    Adapter is not original VAG-COM, but something I bought from local shop specialized in OBD stuff. It was named "OBD-DIAG 3001" and there reads "K/L - KK/L interface" on it. Made in Germany, if I recall right. This model was recommended to me to use with this A3. It should work with VAG-COM 311.2 and 409.1. I tried shareware versions of both of them.

    Looks like I should take car to Audi service and see if they can contact ECU. Maybe it is just this adapter after all, or some strange software problem.
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  6. FactionOne
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    FactionOne Administrator Staff Member Administrator

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    [Jan 30, 2008]
    I think steve's been on the right lines then...

    If I had to guess at what's causing your issue now I would say most likely it is the interface. There is of course a small chance that a newer revision of VAG-COM might better handle any communication timing variations, but more often than not this comes down to the actual hardware.

    Getting it checked out at Audi might be a wise idea - they might want to charge you to plug it in though; if they do I'd suggest maybe a quick telephone call to your local VW/Seat/Skoda dealer - they might do it a little cheaper!

    Regards,

    Rob.
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  7. racc
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    racc New Member

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    [Jan 31, 2008]
    Thanks for you both. You were exactly right!

    I nearly left to Audi service (here it is same company for all VAG cars :ermm: ) but luckily I found an local Audi enthusiast with a genuine Ross-tech(?) adapter. It had no problems with my A3's ECU at all!

    Good thing there also were no serious error codes, only slight problems with one coolant temperature sensor. :happy:

    Hopefully we can investigate next week (with local friendly OBD dealer) if he has any better adapter model for my use. My adapter cost something like 40 euros and adapter we used today was about 300 euros or so. Hopefully there is a working solution between those two.
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