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Help me fix my remote locking (key fob)

Discussion in 'Automotive Electronics' started by Diy1995, Jan 3, 2017.

  1. Diy1995

    Diy1995 Member

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    Hello,
    I am owner of 2000 Renault Clio and my key fob went bad!
    I can start car with the key, but remote unlock / lock is not working.
    First when problem started i had to press multiple times to lock / unlock my car, but one day it stopped working!
    Sometimes i can lock/unlock after few presses, but sometimes its not working at all!
    Led indicator on key does not light up.
    Battery is not the problem, contact with battery is not the problem, microswitch is not the problem (i changed it anyways), i resoldered all bigger joints on board, i measured every single connection and all is OK.
    Key didnt fall in any liquid!
    Im not interseted in buying new key for 150EUR since its 2000 Clio!
    Key Fob is RF type.
    I drawed schematic of board.
    Is the IC chip faulty or could it be anything else?

    [​IMG]

    [​IMG]

    Thank you for your help!!!
     
  2. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    A likely problem is that the receiver (in the car) is not on the same frequency as the transmitter. Both probably use a SAW device to set frequency, but they age and drift to some extent.

    No guarantee it would work even if you replaced the transmitter.
     
  3. Diy1995

    Diy1995 Member

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    Hello, Led indicator on key is not flashing. I reprogramed the key. Thanks.
     
  4. dave

    Dave New Member

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  5. pfofit

    pfofit Member

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    Inside the red circle area, foil trace looks corroded under the green paint. Do a resistance check.
    Whats the other side look like?

    img20170103193921.jpg img20170103193921.jpg
     
  6. hyedenny

    hyedenny Member

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  7. Diy1995

    Diy1995 Member

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  8. GromTag

    GromTag Active Member

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    :A possibility:
    Potential loose battery or minor corroded contacts.

    These devices are quite low current, thus the battery contacts should be checked for any dull oxide or corrosion of any kind, or being loose. Problematic batteries or moisture gets into many things at some point also.

    At times the battery can have loose contact, well my experience with alpine models over years, the LED, (I'm assuming that to be the LED indicator in the image lower left) would show a long on statement and the remote worked fine, some would have a small blip from then LED and a gentle tap on hand would re contact the battery most of the time, the LED was back to normal on statement length. The capacitors can at times store a small amount of power with a loose battery that results in the led blip, the frequency generator and IC code chip with register Code/ID can not start up with this and the LED just blips and no generated code nor respective distance from remote.
     
    • Agree Agree x 1

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