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not the usual w203 boot lock problem

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by ironass, Apr 5, 2011.

  1. ironass

    ironass Member

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    Hi all, First proper post so go easy.

    Ive done quite a bit of searching on this problem and all I seem to find is the usual boot latch needs replacing but thats already done so I think this may be a tad more rare. My boot wouldnt open from the remote when I bought the car and upon inspection I noticed the 4 pin connector had been disconnected but when I re-connected it the motor immediatley started to spin and only stopped at the latch stop but still continued to buzz meaning it was still powered. It got very hot very quickly. I disconnected it and tested the wiring with a meter and it seems to be recieving power all the time. Having done a bit of trawling thru posts I cant assertain wether or not there is a controller for the boot lock as there is for the doors or wether I should be looking in the direction of the remote switch in the window switch array.
    Any and all help would be very much appreciated

    My car is a 2003 W203 C220 CDI auto

    Many thanks

    Mark
     
  2. television

    television Always remembered RIP

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    I have a computer down and cannot check this out just yet
     
  3. OP
    ironass

    ironass Member

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    computer down

    well as I'm a computer tech if there is anything I can help with just ask :D
     
  4. Alex Crow

    Alex Crow Senior Member

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    and is it an estate car? makes a big difference....
     
  5. OP
    ironass

    ironass Member

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    No sorry its a saloon :Oops:
     
  6. Alex Crow

    Alex Crow Senior Member

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    boot opening/closingand boot lights are controlled through the rear sam unit (the fuse and relay module in the boot), as far as i can see it switches the power to the motor. i would be checking all microswitches, and wiring in the hinge area i would think.
     
  7. OP
    ironass

    ironass Member

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    Thanks for that info, I have followed the cables to the fuse unit and havent come across any switches and all the cables look intact. I wonder if you could ID the relevant relay for me as I have no wiring diagram available.

    Many thanks

    Mark.
     
  8. Alex Crow

    Alex Crow Senior Member

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    the switches i describe are microswitches built into the boot handle and/or latch mechanism. and no, there is nothing in the wires between the sam unit and the boot, and there are no specific fuses or relays specifically linked to the boot opening function.

    do the boot lights work ok?
     
  9. OP
    ironass

    ironass Member

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    as far as I can see there are no boot lights and no spare wires to say there may have once been. The handle works fine mechanically and Iv'e tested the lock with the wiring plug removed from the handle completely, (which would discount any micro switches inside it I'm assuming) and the motor is still constantly live. It seems such a simple setup this but there must be something somewhere shorted down to be keeping it fed. Its very frustrating :( but I really appreciate your help
     
  10. television

    television Always remembered RIP

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    I wonder if the remote button is stuck or there is damage to the wiring in this area, though it is can controlled the fault could be in this area
     
  11. OP
    ironass

    ironass Member

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    Checked the wiring it all seems fine and runs along the hinge trim with plenty of free play and no snag points. Once I figure out how to remove the remote switch without damaging it that will be my next investigation tomorrow morning. If it were to be can related do you think it would it affect the rest of the central locking system?
     
  12. television

    television Always remembered RIP

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    Hard question in that as these are CAN operated, if the button was faulty the CAN line could be busy but the CAN signals only normally send one set of numbers at a time so it should not /may not upset the rest
     
  13. Alex Crow

    Alex Crow Senior Member

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    ironass, you are assuming too much - eg disconnecting the microswitches rules them out of the equation, it does not (are they NO or NC? should they be open or closed?). and yes, you DO have a boot light, also triggered by the same microswitches...

    it is clear this has been a problem for someone in the past, with bodged modifications. does the boot lock with the central locking, or is it always unlocked??

    EDIT there is also a microswitch built into the motor assembly, this must be first suspect?
     
    Last edited: Apr 6, 2011
  14. OP
    ironass

    ironass Member

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    Hi Alex
    Thanks for the info. As stated in my original post the lock ass has been changed therefore unless the new replacement is faulty the lock can be ruled out. As for the micro switch in the handle it can be seen through a small aperture and the operation can be seen to be ok. As for it being normally open or closed, 1 how would this affect the operation if it were completely disconnected? and 2 how would I find out/test this? The lock operates all the time regardless of whether the central locking is operated or not and I can open it with the key only if the wiring plug is unplugged.
    This is exactly why I've presented this problem here as sometimes its hard to see things staring you in the face. Finally the boot light, any idea where it should be as I cannot see any sign of it or its wiring.

    Many Many thanks for your help.

    Mark
     
  15. television

    television Always remembered RIP

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    I cannot see it being the lock as the 2 feed lines are live
     
  16. OP
    ironass

    ironass Member

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    How do you mean? are they supposed to be permanently live? :confused:

    Cheers

    Mark.

     

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