318 Onan Electrical System total failure
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    Question 318 Onan Electrical System total failure

    I am stumped! Tractor was running fine and mowing then just quit. No Lights, no ignition, no start, and no clutch power. Battery both + and - connections good. Replaced ignition switch and circuit breaker reconnected battery and there was one click but nothing else. Disconnected battery to check for shorts with continuity tester and found continuity to ground on all three voltage regulator terminals on the Onan engine. Something tells me this is not right. Any help would be appreciated.

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    IndianaJim's Avatar
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    Feb 2013
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    Do you have the TM (technical manual) for the tractor and CTM (component technical manual) for the engine?
    If not, send me a PM, I may be able to help.

    Not saying you dont have an issue with the voltage regulator, but that wouldnt cause it not to start or have no voltage.
    Have you checked the two fuses to be sure they are good? Depending on year, you will have either blade style or the old glass type in round holders. The old style were prone to failure, and were sometimes replaced by dealers.
    When mine was going bad, Id have random times where the whole thing would shut down like someone shut off the key. Nothing would fix it. Random fiddling with stuff would get it going again. Fuse holder looked ok from the outside, but found out it wasnt upon closer inspection. Replaced with blade style and all has been well for the last 20 years.
    Jim B.

    318, 49 Thrower, 2 80 Carts, 17AT cart, 54 Blade, 12" Brinly Plow, 30 Hydraulic Tiller w/extension & Briney 3-Pt hitch, 50 deck w/JRCO Cart Bagger.
    2025R, 120R loader w/Kens Bolt On Hooks, 260B backhoe w/8" & 16" buckets, Titan 36" forks, Imatch hitch, Weight Bracket/Hitch.

    Exmark Lazer Z HP 52"
    Husqvarna 550XP, 562XP, 55 Rancher

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    Smalljob's Avatar
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    Somerest, MA
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    I worked with a friend this weekend on his 1983 318. Symptoms were no start and the oil light was very dim. No other indicators lit.

    No click when trying to start. Good connections battery both plus a negative. Checked ground from battery post to bolt on engine. Read 0 ohms so good. Had him check ground at bolt that holds the solenoid to the side panel of pedestal and it showed open. Ran a jumper from negative of battery to that bolt and all indicators lit up properly and the tractor started right up. Somewhere with all the years of dirt and vibrations he lost a ground connection somewhere.

    It was obviously affecting more than just the solenoid as evidenced by the lack on indicators.

    Not sure what year you have but thought I’d share an unusual experience that is similar.

    Good luck


    Sent from my iPad using Tapatalk

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