Bad Alternator = Blown ECM Fuse?

Discussion in 'Engine & Drivetrain' started by Shibbershabber, Sep 13, 2018.

  1. Shibbershabber

    Shibbershabber Supporting Member

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    Sep 9, 2017
    (1999 Yukon SLE 5.7 ~170k w/~3k on new motor)

    Had the battery light come on last night, alt not charging. New battery.

    Replaced alternator with New 105 amp from Oreilly. Installed it, drove around a bit... all was well.

    On my way to work this morning, it dies while driving... Cranked and cranked but nada...

    Towed home, though it might have been the fuel pump. Stuck the OBD reader on it and got a 'no comm' error.
    Started poking around and found the the ECM-I (20A) fuse had blown.
    Installed a new one and it fired up no problem. Didnt drive it as I need to get to work in the morning and I figure if it blows again, I have 4 backup fuses to get me there.

    Looking at the harnesses, etc I cannot see any of them that are on the exhaust or damaged, etc. No obvious signs of damage anywhere.

    My question is... could my dead/dying alternator have smoked something?

    Then again, if the alternator did it, I probably wouldnt have made it as far as I did before it died. Probably a good 20 minutes of driving before it popped.

    Could something inside the alternator itself have caused that fuse to blow?

    Any thoughts at all???
  2. swathdiver

    swathdiver Full Access Member

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    May 18, 2017
    Treasure Coast, Florida
    It's possible the bad alternator did it but such is conjecture on my part, don't know how it would have done it. Best thing is to take it out on the road for a spell with the spares and get the battery charged back up and see if everything returns to normal.

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