What causes the window to open??

Discussion in 'Electronics' started by GrantA, Dec 22, 2008.

  1. GrantA

    GrantA Member

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    I have started to get some minor electrical problems mainly with the NS rear window which opens occasionally when touching the foot brake or when starting car. After this happens neither the NS rear door switch nor the central switch (between fronts seats) will operate the window to close it. Stop the car, turn the ignition off and then back on and the NS rear door switch operates the window fully but the central switch does not, it appears dead.

    I have tried a search and on one thread it mentioned "bad earths" as a cause for spurious electrical problems but I don't know where all the earths are on my car or where to start looking for the specific one for the NS rear window. BTW the car is a 1999 C220 CDI Estate, any help or advice gratefully received!!

    Grant :confused:
     
  2. Dieselman

    Dieselman Banned

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    The earth points will be in the front footwells under the carpet, but it's more likely to be a door control module gone U/s.

    If it only does it when you apply the brakes it might be worth changing the brake switch in case it's causing spikes.
     
  3. talbir

    talbir Hardcore MB Enthusiast

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    Why drive the MB when you got such a nice Porker ? !

    Love the avatar.

    The likely culprit is the window module/relay, as a short circuit (triggered when you are pressing the brake pedal) is cuasing a block on the relay and hence no reaction until you 'reset' relay, done by switching ignition off and on again.


    talbir
     
  4. OP
    OP
    GrantA

    GrantA Member

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    It also does it sometimes when I start the car so could be a "spike" but the central switch for that window stopped working when the problem started hence my theory it could be a bad earth. Ta anyway I'll check the earths in the footwells and see if that helps.

    Grant
     
  5. OP
    OP
    GrantA

    GrantA Member

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    Does that mean the brake pedal switch/relay and the window module/relay are connected in some way?

    Just checked and with the ignition on, and without starting car, the central switch for the NS rear window is now working. Started the car reversed out of the garage, braked and the fault returned with the window opening and then no way of closing it until ignition switched off and back on. This is going to pi$$ me off until I can find out exactly what is wrong and isolate it or fix the problem. Is the window module/relay in the door? Can I just isolate it (pull it out or disconnect it) until I get a replacement?

    Grant :confused:

    PS. talbir, I nearly bought a much modified slantnose but settled for the 911SC as it "did it" for me. With your list of cars bet you walk round with a permanent smile on your face. :bannana:
     
  6. Dieselman

    Dieselman Banned

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    Yes.
     
  7. OP
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    GrantA

    GrantA Member

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    Thanks Dieselman & talbir, it is definately the window module, started the car this morning, raised the tickover to 2,000rpm and just waited. After a few seconds the NS rear window opened of its own accord, jerky to start with then opened fully and, as before, I had to switch ignition off and on again to get window closed. As advised I'll disconnect the window module until I can get a replacement, difficult here in France other than from the MB stealership.

    Grant :)
     
  8. OP
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    GrantA

    GrantA Member

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    Merry Christmas to one and all it's me again, sorry to bother you on Boxing Day!! :rolleyes:

    It so bl00dy cold outside decided to pull the fuse for the NS rear window rather than freeze my nuts off stripping the door down. Looks like I have to pull the fuse that also affects the central locking - not a big issue. I have tried to find a number or part description for the electric window winder control unit / module. What is it actually called? I can't find any reference to it on the www.detali.ru website or with GSF or EuroCarParts. Without stripping the door down I don't even know what I am looking for, is it just a relay or is it actually an electronic control box? Any and all advice gratefully received.

    Grant :confused:
     
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