Deactivating an Immobiliser - HELP!
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  1. #1
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    Deactivating an Immobiliser - HELP!

    Hi all,

    I had to take out the ECU from my M Reg V6 Cavalier to test it for problems. Luckily it was fine, but after reconnecting it to the car, the car tries to fire up, but the immobilser cuts in and won't let the engine start.

    I've tried disconnecting/reconnecting the battery but that didn't help.

    It looks like the immobiliser is permenantly activated, so any ideas as to how to deactivate it?

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  3. #2
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    I dont think the engine would try to fire if the immobilser were on. There shouldnt be any spark at all. You say its trying to fire? or just turning over?

    The immobliser on my 95 m cdx v6 even cuts the starter motor. Did you have any bother refitting the ecu?
    LET the fun begin.......

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    if the immobiliser is activated, the ecu light will flash constantly when you turn the key.

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    The car is just turning over, not firing. It seems it's cutting out the fuel pump. The funny thing is that the remote central locking/unlocking works with the key fob.

    When refiitng the ECU, there weren't any problems.

    Now I've been told I need to get a immobiliser code from Vauxhall (a car pass) and get them to deactivate it. It's all done through a Tech 2. A couple of people I know have one, but they don't know how to deactivate a immobilised car, or how to enter the code.

    Quite annoying as I'll have to get my Cav towed a few miles to the nearest Vauxhall dealer

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    just get an ecu from a v6 without an immobiliser

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    You sure its not a remote immobiliser problem?

    Cavs were fitted with either chip/transponder or the remote fuel pump cutoff.

    Check around ignition barrell to see if it has transponder immobiliser first, because if it doesn't, its simply a fault where the remote isn't activating the pump. You should know when the pump comes on as you can hear it prime.

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    Quote Originally Posted by JamesMcbride View Post
    just get an ecu from a v6 without an immobiliser
    Would that work?

    I was told that as the immobiliser module on the ignition and the chip on the key fob had to match the ecu, therefore fitting an ecu from another v6 wouldn't work.

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    Quote Originally Posted by John V6 View Post
    Would that work?

    I was told that as the immobiliser module on the ignition and the chip on the key fob had to match the ecu, therefore fitting an ecu from another v6 wouldn't work.

    Right, if you have transponder/chip immobiliser and you want to replace the ECU for another immobiliser ECU, you MUST have the transponder and chip from the key that goes with that ECU, its a set of three. It is possible to get an ECU recoded, but Vauxhall charge big money for that.

    As far as I am aware, you can simply put in an earlier type ECU (Has 'PN' id code in large black letters on the ECU label) and it will bypass the need to worry about transponders/chips etc, as early V6's didn't have it.

    But, you also have virtually no security either is the downside.

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    Right, I've checked with Vauxhall in Luton and they told me that my Cav has a factory fitted alarm and Vauxhall Engine Deadlock 1 Immobiliser (combined).

    I went to 2 Vauxhall dealers to get the immobilser code, only for them to tell me that my Cav doesn't have an immobiliser - as the key fob I have is the standard vauxhall keyfob with remote central locking and doesn't have a chip in the key itself.

    So the dealers told me that there's no point ordering the immobiliser code from Vauxhall, as either the car doesn't have an immobiliser, or if it does, it must be an aftermarket one.

    This is a pain, as I've found someone who knows how to deactivate the immobiliser with a Tech 2 and just needs the 4 digit code that the dealers won't order for me.

    So is there any way I tell for sure if I have a Vauxhall immobiliser or an aftermarket one, or none at all?

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    Take off the steering wheel cowling, and check around the ignition barrell.

    If you don't have a black plastic ring around the barrell that is connected to a small black block, then it DOESN'T have Transponder/Chip immobiliser.

    If you have a remote that only has one button, then you have the immobiliser that locks out the fuel pump.

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    Yep, I have the remote with one button, so it looks like I have the immobiliser that locks out the fuel pump.

    If I fit an ECU from another V6 Cav (immobiliser or non imobiliser model), will it work in my Cav?

    If so, will I have to disable my current immobiliser for the "new" ecu to work?

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    I forgot to add, the remote fob unlocks the car, disables the alarm and the red LED immobiliser light on the right of the dash goes out. All the lights on the dash go out, including the engine management light

    When turning the key in the ignition, it cranks up but doesn't fire. So possibly the fuel pump is locking out - but surely the immobiliser light shouldn't go out if the imobiliser is stopping the fuel pump???

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    Changing ECU will do nothing, as the remote system is a separate entity.

    It might be that the fuel pump is dead, the fuel relay in the drivers foot well is knackered.

    When the immobiliser is switched off when you are sat in the car, you should be able to hear the pump kick in as it primes the fuel lines.

    Check the pump and fuel relay first, if that doesn't work let me know.

    I'll see what I can find out, I've had to bypass this system before but it was such a long time ago.

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    When sat in the car, the fuel pump isn't kicking in, you can't hear any clicks at all - there is a chance it could be knackered along with the fuel pump relay, but unlikely, as these were only replaced a few months ago.

    I suppose this means the immobiliser is in fact activated.

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    Quote Originally Posted by John V6 View Post
    When sat in the car, the fuel pump isn't kicking in, you can't hear any clicks at all - there is a chance it could be knackered along with the fuel pump relay, but unlikely, as these were only replaced a few months ago.

    I suppose this means the immobiliser is in fact activated.
    Only takes one to fail. Disturbed connectors, rubbed wires.

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    is the eml light flashing on the dash mate once the ignition is on???? to see if its got an immoberliser, remove the lower part of the steering cowling and look for an immoberliser ring around the key barrell. if you havnt got one the crankshaft sensor will give you starting problems, if you have got one and need the code vauxhall chrage £14 quid to get the code faxed over......then you can re-prog it with tech 1.

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    Quote Originally Posted by Galahad View Post
    Only takes one to fail. Disturbed connectors, rubbed wires.
    That's True.

    I'll check it out when I can access the car next, which won't be until the new year as it's in my mate's garage and he's away for Christmas.

    It's a real pain in the backside not having the Cav at this time of year.

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    Quote Originally Posted by micky taylor View Post
    is the eml light flashing on the dash mate once the ignition is on????
    The eml light doesn't flash when the ignition is turned on. All the lights go out.

    It's not the standard Vauxhall immobiliser as I asked at the dealer about getting the code, but they said that mine didn't have a code as there isn't a chip in the key itself.

    IIRC, the cars with chips in the key started on the Vectras in 1995. The few Cavaliers that had immobilisers had the one that I've got and the problem is that Vauxhall dealers know little or nothing about them. Even alarm/immobiliser/auto electricians get stumped trying to sort out these Cavs.

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    what about running a temp 12v feed to the fuel pump to make sure that is the problem

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    Quote Originally Posted by John V6 View Post
    The eml light doesn't flash when the ignition is turned on. All the lights go out.

    It's not the standard Vauxhall immobiliser as I asked at the dealer about getting the code, but they said that mine didn't have a code as there isn't a chip in the key itself.

    IIRC, the cars with chips in the key started on the Vectras in 1995. The few Cavaliers that had immobilisers had the one that I've got and the problem is that Vauxhall dealers know little or nothing about them. Even alarm/immobiliser/auto electricians get stumped trying to sort out these Cavs.
    Most 2.0 Ecotec Cavaliers have chip/transponder immobiliser as well as later model V6's and very late model Calibra Turbos

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    I've just had this problem.

    The EML light was flashing when the key was turned, I thought this was the immob...

    I played with all the wires around the immobiliser box (in right hand footwell) - no luck. Then unplugged the relay (fuel pump is combined with an ECU relay, I think there are 2 sets of contacts in this one). Popped the relay back in, wiggled it some more and then it worked fine!!!

    I suggest you really spend some time playing with all the connections in the footwell, below the ECU. Unplug & reseat the relay, immobiliser box, etc... Use contact cleaner, etc...

    Hope it works for ya. I think it's unlikely for the immobilser system to just pack-up, they are pretty good units and were used in loads of vauxhalls.

    But this fault got me worried when it happened!

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