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Checking ignition coil on 2010 Merc 9.9 4-stroke -- no spark, oil light doesn't light

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  • Checking ignition coil on 2010 Merc 9.9 4-stroke -- no spark, oil light doesn't light

    Trying to check this coil out because of starting problems --got no spark on either cylinder, and have checked and eliminated wiring from the picture, including a short in the stop/kill switch circuits.

    The coil is in my (almost cold, dead) hands. The primary side has an orange wire (normally connects to ECU) and a black ground wire. The secondary side has only 2 spark plug wires. The first procedure by the manual is to measure resistance of the primary windings, i.e., from the orange wire to the black wire. I did that and got a very low resistance like the manual said I should(0.3 ohm). So, to me anyway, that checks out the primary windings good enough.

    Now over on the secondary side the procedure says to measure resistance from the end of one of the spark plug wires to the orange wire over on the primary side. If I am reading it right the manual shows a low single digit resistance reading as being normal here(8.5ohm). I measured it and got a high resistance, actually an open circuit, on all my ohmmeter scales. I don't understand this test, why there should be a low resistance between the primary and secondary sides if the secondary windings are not grounded. But maybe they are. Can anyone fill me in on this??

    The question is then, is this a bad coil??

    Also side note I thought the oil light was supposed to light up every time you pulled the pull cord and it doesn't. Its supposed to come on at first start up then shut off.

  • #2
    There was a bulletin on coil testing, use this instead of how it is listed in service manual. 2013-07.pdf
    The ECM turns oil light on when have low oil pressure, you can disconnect oil light and connect it to a 12 volt battery to see if light works.
    Regards
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    • #3
      Thanks a bunch i wish i had known that sooner i was going off the manual expecting it to be right. I tested all other pieces to my electrical system. From what i can tell they all tested good. After testing the coil the way you said i got the proper reading. Does this mean i have a bad cdi unit (the black box). If i had a bad cdi would it cause the oil light not to work when starting, along with not having spark?

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      • #4
        Did you disconnect the stop switch wire(black/yellow) from CDI and check for spark? Peak reading voltage output tests are a better way of testing ignition but you will need a peak reading voltmeter or a DVA adapter connected to a digital multi meter. .
        Regards
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        Mariner Outboard Parts

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        • #5
          Yes i tired disconnecting the kill switches and still no spark, do you have the ignition check section of the manual i can't seem to find the right manual for this model and year. I have a meter that read peak voltages and its a snap on clamp meter idk if thats good enough. Im not that versed with using it and i'm not that great at electrical but i can test stuff. I just need to know what to do. I tested the grounds and cleaned them all. I checked the charge coil for voltage output and it was working, I did all the ignition test that my manual says but not sure if its outdated or if im doing anything wrong. It seems to me that its the cdi because all my other components test out to the book. Other reason is i put a battery to the oil light and it went red, but when i try to start it, it doesn't light up. when starting its supposed to come on for a little if i'm correct and it doesn't. Along with no spark makes me think cdi. But anything you think or advice is appreciated. Im at my wits end with it.

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          • #6
            No a clamp on meter is not a peak reading voltmeter you would need part number 99750A1 multimeter. Leave all wires connected when testing voltage all test are for loaded circuits.
            Tool: Multimeter/DVA Tester 91-99750A1
            Component Test Selector Sw. Position DVA Lead Red DVA Lead Black Voltage Reading(1) @300-3000 RPM
            Coil Primary 400 DVA* Coil () Black (B) Lead (2) ** Coil (+) Orange (O) Lead (2) ** 200 - 280 (1)
            Ignition Charge Coil 400 DVA* Brown Ground 230 - 280 (1)
            Ignition Charge Coil 400 DVA* Blue Ground 20 - 45 (1)
            Stop Circuit 40 DVA Black/Yellow Ground 5 8
            *If using a meter that requires a DVA adapter, place selector switch to the 400 VDC position.
            ** Reverse Polarity
            (1) Readings may vary at cranking speed or at idle speed.
            (2) Back probe the electrical lead bullet connector in order to make connection.
            Regards
            Boats.net
            Mercury Outboard Parts
            MerCruiser Parts
            Force Outboard Parts
            Mariner Outboard Parts

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