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Remote Locking/Immobiliser problem

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by nekomata, Oct 16, 2012.

  1. nekomata

    nekomata Member

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    Hi everyone
    As much as I don't like my first post on a forum being a cry for help, Help! >.<

    I've recently bought an N reg C180, but one problem it has is that the remote locking seems to be acting up, and I'm now stuck with an active immobiliser system that I can't de-arm. I still have full access to the vehicle itself (through manual use of the keys), so what I'm hoping to do is deactivate the immobiliser and just lock the car manually until I can fix the remote locking properly.

    I'l put below everything that I've noted and tried so far in hope that someone can help with what to try next:
    - The key fob is a single button flick out key type
    - I've put new MB batteries in the key fob and checked it with a digital camera. Both the red and infrared LEDs are flashing reasonably brightly.
    - I've tried prying the key fob case apart to double check the connections, but the case appears to be glued closed. I suspect that the problem isn't in the key fob though as infrared is flashing reasonably brightly.
    - I've tried resyncing the key by pressing it twice at the rearview mirror then turning it to position 2 for over 30 seconds. All that happens is that the LEDs flash green and red alternately for about 30s, and the key fob still fails to work.
    - I've been trying the key fob pointed at the driver's door handle and at the rearview mirror from both the front and rear. The driver's door lock is of the blanking plate type with nowhere to insert a physical key.

    Overall, I'm getting the feeling that car isn't seeing the infrared from the key fob, as I'm not getting any feedback to that effect. Is there anything that should flash at me when I push the key fob button? (Keeping in mind that the key might well be unsynced by this point)
    On a related note, is there anywhere in particular that I should be aiming for on the mirror?

    Does anyone have any ideas for what I should try from here, either to get the remote locking activate and de-arm the immobiliser (even if just the once), or any other way to reset the immobiliser?

    Thanks,
    Stu
     
  2. Dec

    Dec Senior Member

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    You should read the thread linked below and follow any links in it as there is some useful checks to make and puts you in the picture as its almost the same as yours… http://forums.mercedesclub.org.uk/showthread.php?p=926384#post926384

    What kind of ignition surround do you have?

    [​IMG]

    [​IMG]


    -When you lock the car you point at the rear view mirror Red LED flash, car locks, immobiliser is armed, engine will not start.

    -When you unlock the car you point at the rear view mirror Green LED flash, car unlocks, immobiliser is disarmed, engine will start.

    If your remote fob is faulty and doesn’t send a signal to the mirror then WHEN THE KEY IS TURNED TO POSITION TWO IN THE IGNITION LOCK the Red and Green LEDs will flash ALTERNATLEY to indicate that the immobiliser is still armed (enabled) so car won't start.

    You need to be certain that the remote is working properly EVERY time that you use the fob button… there appears to be some doubt in your post as to whether it is working properly.

    Dec

    Edit: Do the doors lock and unlock and do Red /Green LEDs flash when you press the remote fob button?
     
    Last edited: Oct 16, 2012
  3. OP
    nekomata

    nekomata Member

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    As I say, there is no response from the car at all when I press the key fob button - if the lights are meant to flash even when the key is non-synced, then I guess that the car isn't seeing the fob.

    Regarding the fob IR brightness, I figured it was probably better to make a video at work: http://www.youtube.com/watch?v=zQhwvjw29NA
    It looks brighter than other example videos/photos I've seen of working fobs, so I figure it should be bright enough for the job

    Seeing as the fob is outputting a signal, I'm guessing that for some reason the rearview mirror is either not seeing it or not understanding it.

    The ignition suround is a type B - lever off/push on type.

    I notice in Molly's case she appears to have gotten lucky and activated the remote system before the cause was resolved - I'll also PM her to ask if she has any techniques in particular she was trying.
     
  4. Dec

    Dec Senior Member

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    In Molly's case the button was stuck/jammed on, it was/is omitting a signal continually.
    Thanks for the video, that remote is working perfectly ok, problem must be elsewhere , check ant fuses that are in any way related to central locking, you should be getting a Red or Green when lock/unlocking.

    Dec

    Edit: Point remote at mirror.

    [​IMG]
     
  5. Dec

    Dec Senior Member

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    Does the car have an alarm?
    Any other keys with the car?
    Are all car battery connections tight and is battery charged?

    Dec
     
  6. OP
    nekomata

    nekomata Member

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    Whilst checking the fuses, I noticed one of them had a 7.5A fuse whilst the reference card stated 20A, so I've swapped that over.

    I have silver stickers in the window stating "Fitted with a Mercedes-Benz approved alarm system" - I've not heard any alarm sounding in the car though, so I can only guess that it doesn't exist or that there's something wrong with it.

    I only have the one key for the car unfortunately.

    I've double check that the battery is tight, and is appears to be powering all electrics fine. Do you know what voltage it should be putting out? If I can find my voltimeter I can make sure it isn't getting low.

    Here's the video of the resync attempt: http://www.youtube.com/watch?v=sm4H-5Y5fCU
     
  7. Dec

    Dec Senior Member

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    Those lights would prove you have enough power, that key is just not being recognised, you should have seen a Red LED on your first press of the fob and a Green LED on your second press of the fob.

    Any chance that at some time a fuse was pulled out from a fuse slot only to be put back into a different adjacent vacant slot, can sometimes happen.

    Below is the immobiliser, located on the underside the foot rest in passenger side footwall.
    Depending what alarm is fitted, if any, there might be some joined up wiring attached to the immobiliser, having joined up wiring in this area would depend entirely on what type of alarm, if any, is fitted.

    When these cars arrived in the UK the didn’t have alarms fitted, just factory fitted immobilisers, as pictured below, the dealers then fitted aftermarket alarms by Scorpion Alarms and, in some cases, integrated these alarms into the factory fitted immobilisers and then stuck the sticker in the window as you mentioned. Its possible if the alarm, if fitted, failed then the immobiliser would not be released.

    You will need to investigate further in the footwall area.

    Dec

    [​IMG]
    [​IMG]
     
  8. OP
    nekomata

    nekomata Member

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    Right, just finishing opening up the footwell area, and taken some pictures of what I've found.
    Just googled that the big metal box is the ABS control, so other than a stereo amplifier, all I can see back there is the immobiliser module.
     

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  9. Dec

    Dec Senior Member

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    There is no sign of the immobiliser wiring being cut/taped into?

    Dec
    Edit; have you ever seen that car start, the mirror LEDS seem to work fine, the do what the should do when the car is still immobilised, the remote looks like its working properly, could that be the wrong key for that car… it’s a real mystery is this one.
     
    Last edited: Oct 17, 2012
  10. GB-C220D

    GB-C220D Senior Member

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    Hi
    I have a similar fault in thread

    http://forums.mercedesclub.org.uk/showthread.php?p=922396

    Dec has been very helpful to me so far.

    Under the foot well in mine is what I think is the alarm box and it seems to be integrated into the immobilise. I too have never seen any sign of the alarm.

    Are the wires to the immobiliser just as you would expect as it came out of the factory? My GREEN one on DEC's Plug A had been hacked into

    ATM I think the system works as
    1 receive infra red signal in mirror
    2 check it is correct if so unlock doors, flash green, disarm immobiliser
    3 send signal on the green wire to the alarm
    4 alarm checks infra red signal if it is correct send signal back into the loom via the green wire.

    If the alarm fails you remove it by connecting the green from the immobiliser to the green going to the loom the car should start.

    From your videos it looks like the immobiliser is not seeing any infra red so it seems to be failing at number 1.

    I am told the immobiliser works on my 220D by isolating a fuel stop valve, But I can not find this valve. I wonder if it is isolating a fuel valve in the LP (Lift?) fuel pump.. I am also told-- Read my tread to save repeating it -- that you can bypass the immobiliser by removing the relay that is operated by the immobiliser and forcing 12v on the output. You could try this and see if it starts


    George
     
    Last edited: Oct 18, 2012
  11. OP
    nekomata

    nekomata Member

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    Here's a pic of the wiring that I managed to grab on my way out to work - there's tape around the green/white and red/white wires. I'll need to spend more time in the morning to pull the tape back and see what's beneath the tape though.

    The car has started ok for me before with this key. As the remote function was acting flaky, I've been manually locking/unlocking the car since I bought it at the beginning of the month. Unfortunately, I accidently activated the remote (and immobiliser) just under a week ago, I haven't been able to activate it again since to switch the immobiliser back off.


    Looking at that other thread, to take the immobiliser out of the question (at least until I can get the car to someone who can fix the remote problem), I just need to connect up some of the wires down there, is that correct?
    (On a related note, do any of the wiring diagrams in the Haynes manual cover this area of the car?)


    Thanks for the help so far guys. I'd be lost trying to figure this out without you :)
     

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  12. Dec

    Dec Senior Member

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    Someone has been at that since the car left the factory, the alarm has been integrated into the factory fitted immobiliser, what you have to do now is revers whatever was done and rejoin the original wires back together.
    Your picture shows the wires that go to Plug B in my picture below?

    [​IMG]
    [​IMG]

    Any loose wire ends should be taped up as the may be live.

    I think, like my previous car, your alarm, a Scorpion, is located under the instrument cluster… remove panel… it is in the centre of this picture here… http://forums.mercedesclub.org.uk/attachment.php?attachmentid=12803&d=1284900436
    Don’t access it at the moment as there is nothing to be gained in getting yours hands on it, it’s the wires in your picture that you need to sort out in order to get the car to start.

    Do you have an alarm siren like the one (with 334 on it)located at bottom right of picture below or elsewhere in the engine compartment?

    Dec

    [​IMG]
     
  13. OP
    nekomata

    nekomata Member

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    I couldn't find that siren (or anything similar) anywhere in the engine compartment.

    HAving pulled back the tape on the green/white wire, I can see that it's had a green/black wire soldered into it. About an inch or so of the green/black remains now, and is taped up against the green/white wire.

    Also, am I right in thinking that the alarm system you're talking about is the one with the additional fob? If so, I have no such fob.
     
  14. GB-C220D

    GB-C220D Senior Member

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    Hi
    you said "Additional Fob" I never knew there would be one either. I thought the single button Mercedes fob worked the alarm.

    George
     
  15. Dec

    Dec Senior Member

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    If your alarm is integrated into the original factory immobiliser, and it looks like it is, then there would be no need for an additional fob as your existing flip out fob would do the job.

    My previous 1994 C180 had an additional fob for the Scorpion alarm but my alarm WASEN’T integrated into the immobiliser.
    So, you reckon you can put that wiring back the way it was when it left the factory?
    The one in the small picture George.

    Dec

    [​IMG]
     
  16. OP
    nekomata

    nekomata Member

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    I can only find the inch of wire that's left soldered into the ones in my picture - I'd have no idea where the wires are that they were part of.

    I've also been looking around for the yellow/red and black/purple wires that have been referenced in other threads, and I can't find them either >.<
     
  17. Dec

    Dec Senior Member

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    So neither of the two taped up wires in your picture have been cut and whatever was spliced/soldered on to them has now been removed?

    So, we are back to square one again, there is something odd here;
    The immobiliser appears to do its job… flash alternately when ignition is turned on.
    The immobiliser wiring appears to be uncut and original???
    The remote seems to work ok.

    Disconnect the battery for a few minutes then reconnect it again.
    Have a look at the electrical connections on the vacuum pump in boot, driver side.
    Check that the battery is charged, it should be able to open a window/run wipers.
    Try synchronising the remote again… press once, at the mirror and put key in ignition and turn ignition ON within 30 seconds.

    Dec

    [​IMG]
     
  18. OP
    nekomata

    nekomata Member

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    At work at the mo - will check those items tomorrow though.

    Whilst it's on my mind though:
    - Do we know where the IR sensor is in the rear view mirror?
    - Do we have any way to test the IR sensor is working fine?
    - Does any processing of the signal happen in the mirror, or does it just covert it to a current, then pump it down a wire to be processed elsewhere?
     
  19. Dec

    Dec Senior Member

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    - Do we know where the IR sensor is in the rear view mirror?
    No, but generally in the direction of the mirror will work, it doesn’t have to be bang on the mirror.


    - Do we have any way to test the IR sensor is working fine?
    Not that I know of.


    - Does any processing of the signal happen in the mirror, or does it just covert it to a current, then pump it down a wire to be processed elsewhere?
    I think that’s is exactly how it works, as you can see from the inside of the immobiliser there is quite a lot going on on the PCB.

    Others may know more.

    Dec
     
  20. television

    television Always remembered RIP

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    IR signals can be traced on an oscilloscope, we have to do this when tracing where the beam starts and stops, it s possible to trace them all the way into the processor that requires the information, It is the only way :D
     

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