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  1. #1
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    1989 XR4 ground wire





    What is this grounding wire for and where does it ground to? I raised the motor in the driveway last night and it started to smoke and melt the cover plate. Plus it would zap the battery pretty quick and the motor won't start, just spins the starter.

    Motor is a 1989 Mercury XR4 150 hp serial #:0C137920

    Just recently had the lower unit replaced so not sure if this had anything to do with it.

  2. Member
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    #2
    thast part of grnd system for mid to swivel brkt/ you got a short some where
    .................................................. ...the scariest thing in life is the unknown ...................................

  3. Member
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    #3
    Thanks for the response. Any idea how I can find a short? I am clueless on this one.

  4. Member
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    #4
    check for spark at batt on red cable when touched or volt meter between pos post and batt cable ,disconnect voltage reg first/ red wires going to it
    .................................................. ...the scariest thing in life is the unknown ...................................

  5. Member
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    #5
    2 quick questions:

    Do I need to replace the ground wire since it was smoking and looks to be a little burnt?

    Is the ground wire supposed to be routed the way it is?

  6. Member
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    #6
    yes to both ? and find short
    .................................................. ...the scariest thing in life is the unknown ...................................

  7. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #7
    Recently reconnect a battery here?


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  8. Member
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    #8
    Pulled off my electronics wiring and just hooked up the positive and negative to the motor and the motor shot right up with no issues and no smoking of the ground wire. Now the battery is dead so it needs a full recharge or might be buying a new battery.

  9. Member lpugh's Avatar
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    #9
    Quote Originally Posted by JOE54 View Post
    check for spark at batt on red cable when touched or volt meter between pos post and batt cable ,disconnect voltage reg first/ red wires going to it

    With your experience I am sure would be aware of battery gassing and take these precautions as I do just as you described sometimes. However non pros need to be aware of this danger.
    Please don't do this, if the battery is gassing for any reason you could experience what it is like to have explode in your face. Do it on the engine side away from the battery. Amp meter instead of voltmeter. No sparks near a battery unless you can be 100% sure the battery is not gassing. Also keep in mind a bad battery can be gassing with no load or charger connectsd. Still not full proof but at least cover the top of the battery with a wet towel
    I learned this the hard while still an apprentice. Battery acid in your eyes is no fun, I was very lucky

    I am not attacking Joe in any way as pros we sometime make the mistake of assuming every one else is aware of this simple precautions
    Last edited by lpugh; 06-20-2018 at 07:02 PM.
    Thank You Leon Pugh

  10. Member
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    #10
    So I charged the battery, messed with some wires and I think the trim up motor might be going bad. The motor goes down with no issues but going up it dogs really slow, struggles, and the ground wire begins to glow again and starts to smoke.

  11. Member lpugh's Avatar
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    #11
    I do not remember how that trim system is grounded, I would check the wiring carefully from the trim motors. I think you will find the ground circuit for the trim motor is open circuit, like in disconnected which may cause it find another path to ground such as the wire that is getting to hot, I don't think that wire is large enough to do the job for trimming up. Look for another ground ckt
    I think that system was two powers, one for up and one for down,
    Also possible that the power up has worn thru the insulation and is making contact and allowing it to pass thru that ground
    I checked my motor, a optimax and it is not even connected and my trim works fine
    I only suspect that wires purpose is for electrolysis control. Maybe some will jump in with more info
    Last edited by lpugh; 06-22-2018 at 12:53 PM.
    Thank You Leon Pugh

  12. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #12
    Check the wires running from inside the cowling to the trim motor for DETERIORATION, chafing, shorting, or bare spots FIRST.

    Also verify if you have 2 wires or 3 wires at the trim motor (that dictates the type of wiring circuitry used).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor