Diode Help

Discussion in 'General Electronics Chat' started by thekidinbuff, Dec 15, 2013.

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  1. thekidinbuff

    Thread Starter New Member

    Jul 16, 2013
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    Hello, to make this short, i had remote start for my car till one day when i shut it off and it shorted out i guess and all it wants to do when its hooked up is turn my starter over.. Ive gone through just about everything and there are two diodes, one a zener and one a 1n4007 diode. Before i un-sodered the 4007, i tested it and it had .162 each way and 0 resistance both ways. Thought that was my problem so i took it off and now it shows OL for reverse bias, which is good. I put a new 4007 in its place anyway, and now that one shows 0 resistance each way.. Im so lost. :confused: Are they good then? They do it without the main chip in too.. Only tries to start the car when i hook the 12V to the remote start module

    Anything will help!
    Thank you!
    TheKidInBuff
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you are testing with the resistance scale, you will not get a correct reading with a semiconductor, you need to use the diode scale if you have one.
    The diode scale should show a value that represents the voltage drop in the forward direction and open circuit in the reverse.
    Depending on the circuit, it will not confirm any true value in circuit.
    Max.
     
  3. thekidinbuff

    Thread Starter New Member

    Jul 16, 2013
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    No i use the continuity/diode option and get 162 on the meter and if i turn the dial and set it on 20M resistance, it shows 0 ohms each way when the diode is on the board. but when it is not, it shows 0 in forward bias and OL in reverse
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    There is most likely something on the board affecting the reading, this is the down side to measuring any component in circuit.
    Max.
     
  5. #12

    Expert

    Nov 30, 2010
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  6. thekidinbuff

    Thread Starter New Member

    Jul 16, 2013
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    Alright, thank you. I will post this over there.
     
  7. alfacliff

    Well-Known Member

    Dec 13, 2013
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    thde diode is priobably across a relay coil to supress counter emf. check the diode with one lead unhooked, if it checks ok, check what ever the diode is across.
    cliff
     
  8. Wendy

    Moderator

    Mar 24, 2008
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    2,536
    The owners of All About Circuits has elected not to host discussions of automotive electrical system modifications/enhancements due to safety concerns, the potential of legal ramifications and the possible circumvention of vehicle regulations at the state and federal level.

    This thread is against the AAC forum rules, Chapter 6, as seen here:

    This can be found in our Terms of Service (ToS)

    Automotive modifications of any kind are strictly forbidden. Therefore, this thread will be closed.

    Please try to understand the reasons behind this action, and feel free to browse and use the forums.

    You might find answers to your questions in one of these forums:

    http://forum.allaboutcircuits.com/showthread.php?t=54400

    Another good forum that shares many of the same membership is http://www.electro-tech-online.com/ . Good luck.
     
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