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the dreaded immobiliser thread

Discussion in 'A4/S4 forum(B5 Chassis)' started by tracer, Jul 27, 2006.

  1. tracer
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    tracer '96 a4 1.8 se

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    [Jul 27, 2006]
    wish i wasn't typing this. i have the immobiliser bug. turn key, car starts, car instantly dies, yellow/orange key symbol flashes. again turn key car starts fine.
    and various other combinations, i have now taken to turning key half way waiting for light to either go out or start flashing and take it from there.

    this thread --> has a valid point about spraying the area with wd40 and it works but not for long, maybe overnight or a full day if i'm lucky then after that same again http://www.audifans.net/modules.php?name=Forums&file=viewtopic&p=65755

    spraying inside the ignition key barrel, with wd40, dpr or even just with an air line seems to work best. but maybe its coincidence, i mean sometimes if i work key back and forth for long enough it doesn't happen.

    anyway its now really nipping my tits and i want to get to the back of it. anyone here managed to overcome it? am i looking in the right place? or should i concentrate on wiring connections.

    can someone tell me all the parts that are immobiliser related and where they are located roughly.
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  3. marmite
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    marmite Counting the Tesco Club points

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    [Jul 27, 2006]
    There are 4 main parts to the immo system
    1.Key
    2.reader coil
    4.Loom
    5.control unit

    How many keys do you have? try them all, turn ign on and wait to see what happens with the light, does it go out or keep flashing?

    This highlight if a key prob, poss if key dropped too many times

    Next..

    You change change the loom that goes from the reader coil(ign barrel) to the control unit about £12 and 1 hrs work max, they had a prob with the shielding on the looms.

    Next..

    Reader coil..this can be checked by using Daig equipment if they know what they are doing that is!

    If it was me I would check the keys..if only got one then get another that way they will recode the key too and try that..if not check to see if the loom has been replaced yet..do that and give it ago..1 little trick is if it is playing up move the steering column up and down and in and out if it works after that 120% the loom!!

    Enjoy and I hope this is some help..

    If not replace all the above!! silly sorry but that is tyical dealer:keule:
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  4. marmite
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    marmite Counting the Tesco Club points

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    [Jul 27, 2006]
    There are 4 main parts to the immo system
    1.Key
    2.reader coil
    4.Loom
    5.control unit

    How many keys do you have? try them all, turn ign on and wait to see what happens with the light, does it go out or keep flashing?

    This highlight if a key prob, poss if key dropped too many times

    Next..

    You change change the loom that goes from the reader coil(ign barrel) to the control unit about £12 and 1 hrs work max, they had a prob with the shielding on the looms.

    Next..

    Reader coil..this can be checked by using Diag equipment if they know what they are doing that is!

    If it was me I would check the keys..if only got one then get another that way they will recode the key too and try that..if not check to see if the loom has been replaced yet..do that and give it ago..1 little trick is if it is playing up move the steering column up and down and in and out if it works after that 120% the loom!!

    Enjoy and I hope this is some help..

    If not replace all the above!! silly sorry but that is tyical dealer:keule:
    #3
  5. tracer
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    tracer '96 a4 1.8 se

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    [Jul 27, 2006]
    nice one, great info,

    will try your suggestions, good thinking like, i am impressed.
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  6. marmite
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    marmite Counting the Tesco Club points

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    [Jul 27, 2006]
    Give it a try you got nothing to loose.
    If you get the keys recoded ask them the reset adaptions on the control unit and the engine control unit.
    This is the setting that combines the 2 together, they should do this before anything else, plus reset basic setting on control unit is never a bad thing.

    Remember if you start playing around with it it could go wrong and then you will need to recover car to dealer.

    So depend on your diag..use there carpark..naughty but who cares???:moa:

    Good Luck.

    If changing the loom and unsure PM me and I will guide you through it can be a pain.

    Enjoy
    #5
  7. tracer
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    tracer '96 a4 1.8 se

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    [Jul 27, 2006]
    just went out and tried all keys, all the same. had tried one spare before but am sure now. not the keys.

    tried moving steering wheel up/down. seems to work more fully up than it does fully down. so i'm gonna change the loom.

    will get hold of the loom and change it out, for peace of mind if nothing else. if that doesn't help at least its one thing eliminated.

    thanks for the offer, if i get stuck i'l pm you, should be arite. amazing car you have there btw, waitin to see pics.
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  8. marmite
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    marmite Counting the Tesco Club points

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    [Jul 27, 2006]
    Remove the dash under tray Easy!
    Now you need to get to the ign barrel
    Remove steering couling top part first, 2 screws,
    You will need to remove the steering wheel too, so don't turn ign on once airbag is off or the light will stay on.

    Trims unscrew but you will have to remove the column hight adjust handle...
    The loom has only got 2 wires and has a plug at the ign barrel end and you will need to push out the pins of the old loom on the black control unit plug.use safty pin then just push the pins from the new loom in job done.

    The prob they had is just behind the barrel they cable tie the loom to the steering lock housing and the insulation is to thin and you get interference, they used to wrap foil around it but that never worked.

    Good I hope this works out for you could be nice cheap repair.

    My RS6 I love it only had it a week and done 100 miles in it but done 3/4 tank of fuel lead boot syndrome!! I'll learn..but its fun learning..
    #7
  9. tracer
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    tracer '96 a4 1.8 se

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    [Aug 2, 2006]
    jobs a good 'un. went to dealer to ask for new wiring for the reader coil<->immobiliser control unit but one of the service guys reckoned they see this fault quite often on the older a4s and its not worth getting new wiring, just wrap it in insulating tape.

    so... i removed steering wheel and stripped down all the surrounding trim. found the reader coil and there's the two core cable which is bunched in with the rest of the wiring loom. i have now wrapped this with self-amalgamating tape and rerouted it away from the rest of the wiring (thanks to an old post by fezzR for this tip)

    all back together now and fault has gone!!! :thumbs-up: :rockwoot:

    thanks for ur help marmite, much appreciated.

    just have my exhaust to look at now and see if i can get those front abs sensors to budge out of their housing.

    oh yeah and i'l now have to find out why my doors don't open when the battery is disconnected. imagine, you remove the battery earth, then remove the steering wheel /airbag etc. get to the wire yer looking for and then decide to lock up and start again in the morning. you lock all the doors either by hand or with the key - coz theres no central locking. next morning you come back turn the key in drivers door and the lockpin moves but door won't open. :tocktock: you do the same at passenger side, pin moves but door wont open. :ermm:

    in fact the only thing i could open was the boot. so....... i now have a fully functioning ski hatch!! from there i was able to open the rear door by pulling the inside handle (using a allen key cable-tied onto a golf club no less). dono what any onlookers would have thought.

    i can laugh now but it wasn't funny at the time.
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  10. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Aug 2, 2006]
    "using a allen key cable-tied onto a golf club no less"
    Very inventive, was that an option on the A4?
    #9
  11. jdp1962
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    jdp1962 Grumpy Old Moderator Staff Member Moderator

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    [Aug 2, 2006]
    Standard on the SE, or part of the optional "Sport" pack.:biggrin:
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  12. Fraser
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    Fraser Member

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    [Sep 25, 2010]
    Ok so have got to the point where I have access to the cables on the back of the key barrel

    which wires are they? apprieciate a quick response as car is in bits!

    [​IMG]
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  13. Fraser
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    Fraser Member

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    [Sep 25, 2010]
    been told they are on the other side ?

    [​IMG]
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  14. Fraser
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    Fraser Member

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    [Sep 25, 2010]
    all insulated and back together - will see if this fixes it
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  15. NineNails
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    NineNails Proud sponsor of the snack food industry

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    [Sep 25, 2010]
    Yes, they are the two wires. It's not related to any interference problems as far as I know but rather just a bad connection. The two wires are simply insulation displacement connections onto their pins and over time just start getting weak which is not helped by people ajusting the steering wheel as the loom can be a little short. taping them up can cure it but its a matter of luck because you havent really sorted it. On my old A4 I re-made the connections and cable tied the loom to the lock barrel leaving a bit of slack.
    On a side note....Spraying WD40 into the lock isn't a good idea because all it does is flush out the graphite grease thats supposed to be in there.
    Hope this helps
    Si.
    #14

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