Whats an Immobilizer??

Discussion in 'General Motoring' started by Dave Edwards, May 1, 2008.

  1. Dave Edwards

    Dave Edwards Guest

    Every now and then, my 2001 V40 wagon will not start. No cranking, no
    solenoid click, no nothing. Try all day, turning the key does nothing.
    Wait a day or two, and it starts right up. I also tried it in neutral
    thinking the shift switch was flakey. Tried a new starter thinking it had a
    dead spot. Also tried the spare key thinking the key's theft smarts were
    dead.

    So, I broke down and brought it to Volvo.
    Two fault codes were on the system
    One had to do with the temp sender, the other had to do with the
    immobilizer.
    I was told either could cause this problem...both will run over 500 bucks
    each.

    So, I'm stuck with giving one a try...then the other, and hope the tow
    charges don't add up too much!!

    My question is ...what is an immobilizer, and what the heck does it do...or
    not do?
    Anyone hear of one going haywire?

    Thanks!
    ....Dave
     
    Dave Edwards, May 1, 2008
    #1
  2. i think the immobilizer is tied into the security
    system....
     
    ~^ beancounter ~^, May 1, 2008
    #2
  3. Dave Edwards

    Andy Guest

    Hi Dave,

    The immobilizer does what it says: It immobilizes the engine when the
    security system is set.
    I checked mine ('97 850) by opening the driver's window then locking the
    door with the key to set security. (Red LED flashing on the dash.) When I
    reached in through the open window and turned the key in the ignition, guess
    what......as in your case, "nothing happened".

    Good Luck with the fix. (Wish I had my trusty '93 240 wagon back. No
    complex immobilizer! Who'd want to steal a 240 wagon?!!)

    Andy I. ('58 445 "Duett" wagon; '65 122S wagon; '67 121 direct import
    2-door; '74 140 wagon; '74 140 2-door; '86 240 wagon; '93 240 "Classic"
    wagon; '97 850 AWD Turbo wagon.) Incidentally, all stick-shift...... our
    preference.


    : Every now and then, my 2001 V40 wagon will not start. No cranking, no
    : solenoid click, no nothing. Try all day, turning the key does nothing.
    : Wait a day or two, and it starts right up. I also tried it in neutral
    : thinking the shift switch was flakey. Tried a new starter thinking it had
    a
    : dead spot. Also tried the spare key thinking the key's theft smarts were
    : dead.
    :
    : So, I broke down and brought it to Volvo.
    : Two fault codes were on the system
    : One had to do with the temp sender, the other had to do with the
    : immobilizer.
    : I was told either could cause this problem...both will run over 500 bucks
    : each.
    :
    : So, I'm stuck with giving one a try...then the other, and hope the tow
    : charges don't add up too much!!
    :
    : My question is ...what is an immobilizer, and what the heck does it
    do...or
    : not do?
    : Anyone hear of one going haywire?
    :
    : Thanks!
    : ...Dave
    :
    :
     
    Andy, May 1, 2008
    #3
  4. Dave Edwards

    Someone Guest

    If you can, disable the immobilizer by pulling the fuse. Don't know
    what else is on that fuse (if any) for your V40.
     
    Someone, May 1, 2008
    #4
  5. Dave Edwards

    James Sweet Guest


    Wouldn't that defeat the purpose of an immobilizer?
     
    James Sweet, May 1, 2008
    #5
  6. According to my manual ('00 V40) Immobilizer, Airbag, DSA and
    instrument cluster (fuse #11).
    But I guess, pulling the fuse will activate the immobilizer
    immediatly.


    Roland
     
    Roland Messerschmidt, May 1, 2008
    #6
  7. Dave Edwards

    Dave Edwards Guest

    I have not checked, but my guess is that pulling the fuse would default it
    the wrong way....won't start. Doesn't that sound correct?
    ....Dave
     
    Dave Edwards, May 1, 2008
    #7
  8. Dave Edwards

    Someone Guest

    Try it and let us know. Depending how "smart" those engineers are...
    I'm willing to bet that pulling the fuse will kill the immobilizer.

    My point was trying to isolate the problem. Since you don't know
    which one it is between the two. I'm not sure if you can drive the
    car without intrument cluster...

    Btw, I pulled the fuse on the ABS for my 240s. (I also disconnected
    the 15 yrs old airbag - to each his own).
     
    Someone, May 2, 2008
    #8
  9. Dave Edwards

    mjc13 Guest

    Andy wrote:
    (...)
    (...)

    I've always wondered what that base model 121 was like. Would you
    mind describing the trim and interior, and how well the single carb
    engine pulled?
     
    mjc13, May 2, 2008
    #9
  10. Dave Edwards

    James Sweet Guest


    I would be absolutely stunned if pulling the fuse allowed the car to start.
    I've seen some bad engineering, but there's no way something that moronic
    would end up in a Volvo. Pulling the fuse will disable the immobilizer, and
    the car.
     
    James Sweet, May 2, 2008
    #10
  11. Dave Edwards

    Someone Guest

    Actually, I'm more concerned about the instrument cluster. I have
    difficulty imagining being able to start the car without it. The ABS
    is a non-issue, and so is the DSA (Dynamic Stability Assistance). So
    it only leaves the immobilizer and the instrument cluster.

    From a logical point of view, disabling the immobilizer should shut it
    down. It all depends how they programmed it in the computer.
    Normally, if a protection system is dead, it doesn't perform it's
    function.

    Again, my suggestion was to try finding which one of the two
    possibilities is his problem. Proceeding by elimination is usually
    the easiest approach (and often the cheapest).
     
    Someone, May 2, 2008
    #11
  12. Dave Edwards

    James Sweet Guest


    I don't know where you get your logic... The immobilizer is more like the
    ignition system or fuel injection system, in fact I would guess it's
    integrated pretty tightly into that. Engine management doesn't receive a
    signal from the immobilizer system, it won't let the engine start. Like I
    said, if it can be defeated by removing the fuse, then it is completely
    useless for the design purpose. It would be like a big lock on your front
    door held in by just one exposed thumbscrew. If it were the case, every
    thief would know about it and there would be publicity very quickly.
    Somebody go ahead and try so this stupid thread can end.

    Many cars can be started with the instrument panel fuse removed, I wouldn't
    advise driving around like that but unless it's on the same fuse as the
    engine management stuff, the car will run just the same.
     
    James Sweet, May 2, 2008
    #12
  13. Dave Edwards

    Andy Guest

    Hi "mjc13",

    Sorry to say the single carb set-up had already been replaced by a twin-SU
    system when I acquired the car so I can't comment on the original
    performance.
    The trim was the same as our '95 122S wagon. It had front disc brakes but I
    seem to remember no servo booster! However it handled well, cornering as if
    on rails (or so it appeared at the time......) Exciting too, with a
    Kilometre per hour speedo, roaring through the city at 50! (Km/h........)
    Fortunately, Canada was just about to change to Metric about that time.
    Others were chasing around for stickers to adapt their speedos to Metric.
    Of course their odometers continued to register miles

    Thanks for your interest.
    Andy I.


    : Andy wrote:
    : (...)
    : >
    : > Andy I. ('58 445 "Duett" wagon; '65 122S wagon; '67 121 direct import
    : > 2-door; '74 140 wagon; '74 140 2-door; '86 240 wagon; '93 240 "Classic"
    : > wagon; '97 850 AWD Turbo wagon.) Incidentally, all stick-shift......
    our
    : > preference.
    : >
    : (...)
    :
    : I've always wondered what that base model 121 was like. Would you
    : mind describing the trim and interior, and how well the single carb
    : engine pulled?
     
    Andy, May 2, 2008
    #13
  14. Dave Edwards

    Someone Guest

    I interpreted the immobilizer to be a third party system. Not a
    renamed ignition system or renamed fuel injection system.

    I remember helping a friend who has a 97 960 and the fuse box
    mentionned ignition coil, fuel injection. I guess immobilizer came
    later.
     
    Someone, May 2, 2008
    #14
  15. Dave Edwards

    mjc13 Guest


    I'm guessing you mean "'65 122S wagon"! Interesting that the trim
    was the same - I had read that they had no bumperettes and much less
    chrome. Maybe by that time they had to add that stuff to keep selling
    them...
     
    mjc13, May 3, 2008
    #15
  16. Dave Edwards

    Andy Guest

    : Andy wrote:
    :
    : > Hi "mjc13",
    : >
    : > Sorry to say the single carb set-up had already been replaced by a
    twin-SU
    : > system when I acquired the car so I can't comment on the original
    : > performance.
    : > The trim was the same as our '95 122S wagon. It had front disc brakes
    but I
    : > seem to remember no servo booster! However it handled well, cornering
    as if
    : > on rails (or so it appeared at the time......) Exciting too, with a
    : > Kilometre per hour speedo, roaring through the city at 50!
    (Km/h........)
    : > Fortunately, Canada was just about to change to Metric about that time.
    : > Others were chasing around for stickers to adapt their speedos to
    Metric.
    : > Of course their odometers continued to register miles
    : >
    : > Thanks for your interest.
    : > Andy I.
    :
    :
    : I'm guessing you mean "'65 122S wagon"! Interesting that the trim
    : was the same - I had read that they had no bumperettes and much less
    : chrome. Maybe by that time they had to add that stuff to keep selling
    : them...

    Hi "mjc13",

    I've just checked a photo I took of the old '67 121. The rear end clearly
    shows bumper "over-riders". Is that what you call "bumperettes? The side
    view shows the usual chrome.
    Thanks for correcting the year of our 122S wagon. It would be nice to find
    a '93 model!

    Cheers.
    Andy I.
     
    Andy, May 3, 2008
    #16
  17. Dave Edwards

    Ken Phillips Guest

    I have to agree with James, re. the logic of the immobiliser. The
    purpose of which is to stop any unauthorised person starting the car, my
    poor '87 740 has two third party ones fitted (don't ask; it just ended
    up that way), one (a single circuit one) is part of the remote alarm,
    which also handles remote central locking (very cool!) - this is
    manufactured by serpi star. The other system (a two circuit one, every
    wire is black) is just an ex BMW, laser line 'contact fob' immobiliser.
    I fitted both of these systems (Yes I know! Just who is going to want to
    steal it? LOL), and know full well that disconnecting power to either
    system will cause a no crank, and/or no fire situation.
    A manufacturer installed and specified to modernish standards system,
    such as fords PATS would be very tightly integrated into the cars
    electrics, they are also usually very difficult to find in the car,
    especially the bits that really matter, and the wiring is usually
    coloured and designed to be as obscure as possible.
    It would be really dumb if such a system could be disabled by removing a
    fuse.

    Best wishes, Ken Phillips
     
    Ken Phillips, May 3, 2008
    #17
  18. Dave Edwards

    Elder Guest

    Yes but it would help narrow down and id the fault, rather than spend
    $500 on the wrong "fix" then $500 on the right one.
     
    Elder, May 3, 2008
    #18
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