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Thread: Immobiliser + ECU problem on 1986 BMW E30 325i

  1. #1
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    Immobiliser + ECU problem on 1986 BMW E30 325i

    Can anyone advise, on how to deactivate a faulty Immobiliser from the ECU to allow vehicle to start ?

    My 1986 BMW E30 325i has a genuine English BMW Immobiliser on the driver's door which has died. We have tried everything to deactivate the wiring from the Immobiliser to the vehicles ECU. The vechicle has an original BMW Motronic 1.0 which uses a 2-row 35-pin connector on the ECU. We have not been able to find any wiring diagrams on the
    ECU which show wiring back to Immobiliser. Vehicle has been sitting idle for 12 months.

    Look forward to any suggestions, on how to get this vehicle started, thanks.BMW 325i (1).JPG

  2. #2
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    Nice looking 'vert fella, schweet.
    ironically, on the recent TopGear with 3 e30 convertibles, the easiest to start and steal was Hammonds with exactly the same BMW immob. as you.

    One item I would check is behind the glovebox panel, a two pin connector with green wires. If the wires disappear into the loom... just remove connector and jumper the two pins. the green wires are the feed for the ignition.

    Heaps of e30 experts in Melbourne...

  3. #3
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    yeah mine had that its very simple. just connect the c104 to the ecu.
    Old E30: 323i, 14 PSI T3/T4 Turbo, Megasquirt II 3.57, 3.73lsd
    Current E30: e30 318i m40b18

  4. #4
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    Thanks Guys for your advise.

    We have removed the connector and tried to jump the Green wires but this has not worked to get vehicle started.

    Can you please explain, what the C104 is and where it can be found to connect to ECU ?

    Thanks.

  5. #5
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    Can you confirm what happens when you turn the key to start? does the starter spin?

  6. #6
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    btw is this e30 an automatic? a faulty selector switch can also inhibit the starter

  7. #7
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    Old E30: 323i, 14 PSI T3/T4 Turbo, Megasquirt II 3.57, 3.73lsd
    Current E30: e30 318i m40b18

  8. #8
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    1986 BMW E30 325i Convertible AUTOMATIC

    Thanks for replies to my problem.

    When ignition key is turned,

    the starter spins the engine, no spark and no injection pulse.

    1986 BMW E30 325i Convertible AUTOMATIC transmission

  9. #9
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    Your symptoms are due to an issue with the timing/engine speed sensor, not the immobiliser.
    Can you confirm if you have the two sensors on the gearbox housing?
    may just be a bad connection. remove and clean the plug from the sensors to the engine loom under the throttle body

  10. #10
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    sensors are fine, there are 2 of them and both providing a signal that
    I measured at the ECU computer as well confirming wiring is also OK.

    Sensor connections are NOT mixed up either.

  11. #11
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    Immobiliser + ECU problem on 1986 BMW E30 325i Auto

    Quote Originally Posted by Gruelius View Post
    Dear Gruelius,

    You mentioned in a previous message that you had the same problem with your immobiliser breaking down and preventing the vehicle from starting. My mechanic has tried everything to get the vehicle operating again without success.

    The starter spins the engine, but no spark and no injection pulse.

    We have had the ECU checked twice for faults but both times it has shown no faults.

    We have tried everything to deactivate the wiring from the Immobiliser to the vehicles

    ECU. The vechicle has an original BMW Motronic 1.0 which uses a 2-row 35-pin connector

    on the ECU.

    We have not been able to find any wiring diagrams on the ECU which show wiring back to Immobiliser.

    Any advise or help would be appreciated.

    Thanks,

    Vincent

  12. #12
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    take photos of all the connectors coming from the harness that are inside the car.

    im guessing its different to my one and its working in a different method, if therea re odd connectors on the chassis harness it will prove my idea.

    When the car is in the run position, does the coil get power? also check main/fuel relay ground and see if it is open or closed. If the immobiliser just cuts the ignitoon power to the main relays/coil it would be an easy fix but if it opens the switching circuit you will need to add another relay/transistor to manipulate it.

    i also had trouble finding any info on it (BMW aust denied it was an actual bmw part when i gave them the #, had bmw stamped on it..), but in my case it was very simple to bypass it (ljet is simple)

    other option is that it could be manipulating the ignition power, simple way to solve that would be to just bypass it, hopefully it would be in an ovbious position. (would be inbetween ignition switch and the fusebox)
    Last edited by Gruelius; 03-04-2011 at 01:12 PM.
    Old E30: 323i, 14 PSI T3/T4 Turbo, Megasquirt II 3.57, 3.73lsd
    Current E30: e30 318i m40b18

  13. #13
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    BMW-83.pdfBMW-84.pdfHi Gruelius,

    Thank you for your information above.

    My mechanic has tried the above suggestions with no luck.

    Please find attached, a photo of the immobiliser on the door and a photo of my wiring 35 pin ECU.

    We need to identify the immobiliser wires and disconnect them and hopefully the vehicle will start.

    Regards,

    Vincent
    Attached Images Attached Images

  14. #14
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    BMW 84 pdf is my original ECU which we are trying to disconnect immobiliser wires from.

  15. #15
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    BMW-84.pdf

    Hi Gruelius,

    Thank you for your information above.

    My mechanic has tried the above suggestions with no luck.

    Please find attached, a photo of the immobiliser on the door and a photo of my wiring 35 pin ECU.

    We need to identify the immobiliser wires and disconnect them and hopefully the vehicle will start.

    Regards,

    Vincent

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