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Thread: Coil testing

  1. #1

    Default Coil testing

    How do you test an ignition coil in a magneto system using a digital multimeter?

    Jeff

  2. #2
    Join Date
    Apr 2010
    Posts
    1,291

    Default Re: Coil testing

    All you can do is check resistance of the primary and seconday circuits and it still may not fire. The only proper way to check a coil is with a shop load tester. Best thing you can do is swap it with one that is firing and see what happens.

  3. #3

    Default Re: Coil testing

    Where can I get one of these load testers you mentioned?

  4. #4
    Join Date
    Feb 2001
    Location
    Central West Florida
    Posts
    12,062

    Default Re: Coil testing

    (Regular Magneto Coils - Continuity Test)
    (J. Reeves)

    Checking the continuity of the ignition coils....... Have the ohm meter set to High Ohms.
    Remove the primary wire from points. Remove the coil ground wire. You do not want either of these wires touching anything.

    Connect the black lead of a ohm meter to the spark plug boot terminal, then with the red ohm meter lead, touch the ground wire of the coil.

    Then touch (still with the red lead) the primary wire. You should get a reading on both touches (contacts). If not, check the spring terminal inside the rubber boots of the spark plug wire.

    If there is no continuity between the secondary circuit (spark plug) wire and the primary or ground, remove the coil from the armature plate, then check the continuity directly between the prong within the coil (prong that the plug wire connects to) and the primary and ground. Poor or no continuity of a coil (or plug wire) is one reason for weak spark, s/plug fouling, or no spark.
    Last edited by joereeves; 04-30-2011 at 09:02 PM.
    Our questions require answers. If you refuse to answer our questions, how can we answer yours?

  5. #5

    Default Re: Coil testing

    Thank you Joe.

  6. #6
    Join Date
    Apr 2010
    Posts
    1,291

    Default Re: Coil testing

    A coil could still be bad after all the ohmmeter cks such as a leak to ground under load. Most good dlrs have these testers, especially the ones that deal in smaller mtrs. I've had it happen to me.

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