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It doesn't seem to be alternator

Discussion in '3rd Gen Builds (1996-2002)' started by farmer, Jan 30, 2020.

  1. Jan 30, 2020 at 3:59 PM
    #1
    farmer

    farmer [OP] New Member

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    i have a 2001 4runner that has quit running on its own. I thought it was the alternator but when i went to buy a new one we tested it. It was good on testing. so we went home and replaced with one off another truck. Still the same problem. we replaced both battery terminals hoping.
    The 4runner will start fine if jumped off but soon cuts off from low battery. ( about 2 to 5 minutes ).
    None of the dash electric works. radio, ac, none of the gauges. we searched the fuses and replaced the main power 30 amp under dash. it had some corrosion but looked solid.
    we checked voltage from the alternator and it is jumpng from 6 to 12. Never the 14 we expected.
    I am going back out to charge the battery and try again tomorrow. Has anyone had something similar happen?
    thanks just a farmer
     
  2. Jan 30, 2020 at 4:26 PM
    #2
    SlvrSlug

    SlvrSlug Slightly bent.

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    Welcome to the forum, do know the condition of the battery?
     
  3. Jan 30, 2020 at 7:00 PM
    #3
    farmer

    farmer [OP] New Member

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    On the charger now. Not certain its good
     
  4. Jan 31, 2020 at 9:28 AM
    #4
    farmer

    farmer [OP] New Member

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    Fully charged battery, cranks fine but gauges etc still dead.
     
  5. Feb 1, 2020 at 9:02 AM
    #5
    4x Old Guy

    4x Old Guy New Member

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    If the battery is bad, it will not provide enough current to the alternator to create the electromagnetic field in the rotor coils. With no magnetic field present, there will be no current produced (a conductor passing through a magnetic field produces current in the conductor).

    https://www.howacarworks.com/basics/how-the-charging-system-works
     
  6. Feb 1, 2020 at 10:06 AM
    #6
    farmer

    farmer [OP] New Member

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    The battery held the charge all day but weakened by the end of the day. Retested the alternator at auto zone while running. Putting out only twelve amp but we hope it's in the ground. Haven't checked yet. still open to ideas.
     
  7. Feb 1, 2020 at 11:36 AM
    #7
    farmer

    farmer [OP] New Member

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    We changed battery but still no change. we have changed the alternator. The only thing i can think of is checking the ground wire at engine block which i checked. So tight i wasnt able to break it loose yet.
     
  8. Feb 3, 2020 at 7:51 AM
    #8
    farmer

    farmer [OP] New Member

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    Fixed it. I know we checked fuses with a meter. All were good. Remember the gauges didnt work on dash? I went back and pulled it. The fuse
    Looked good. Then it crumbled inside. Replaced the fuse for gauges and alternator and dash work. That was so easy it only took hours for a one minute fix. But im a farmer.
     
    DesertRoads and SlvrSlug like this.
  9. Feb 3, 2020 at 11:06 AM
    #9
    4x Old Guy

    4x Old Guy New Member

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    Don’t let it get you down. Fuses can look good, but can develop a crack that opens the circuit without “looking” like it’s blown. Only sure way is to use a 12v automotive test light and check both sides of fuse. If light lights on one side of fuse but not the other, the fuse is bad. If it doesn’t light on either side, then the circuit is not energized (probably by design).

    Test light is also handy for checking other automotive electrical.

    https://www.googleadservices.com/pa...wiDhbamirbnAhVxGTQIHdUjBQYQwg96BAgLECQ&adurl=
     
  10. Feb 3, 2020 at 2:58 PM
    #10
    thirdgen

    thirdgen New Member

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    Persistence and a good testlight goes a long way!!
    Good Job!
     
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