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Electrical issue

Discussion in '2nd Gen. Tacomas (2005-2015)' started by Crippler25, Mar 25, 2020.

  1. Mar 25, 2020 at 4:36 PM
    #1
    Crippler25

    Crippler25 [OP] Member

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    I have a 2009 2.7 4wd. I have gone through several batteries and changed the alternator 4 times. Whenever the truck hits around 2100 rpms either moving or in neutral my battery light comes on and stays on. I have to recycle the key and it goes off. If I shift any gear under 2100 the light does not appear on the dash. Im pulling my hair out for months over this.
     
  2. Mar 25, 2020 at 7:29 PM
    #2
    Jimmyh

    Jimmyh Well-Known Member

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  3. Mar 25, 2020 at 7:56 PM
    #3
    TnShooter

    TnShooter Well-Known Member

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    Check the plug that connects into the alternator.
    There have been people that found corrosion at or near the plug.
    You may have to pull back some of the wire insulation to see it.

    There’s probably a better way to check it, like a resistance test?
    But I’m not an expert on the subject.

    I believe @Muddinfun may have some experience with it?
    He may know what wire?

    My guess would be the white wire?
     
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  4. Mar 25, 2020 at 9:06 PM
    #4
    Muddinfun

    Muddinfun Well-Known Member

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    The whole 2100 rpm thing is pretty strange. The 1st thing I would check is the charging voltage at the battery posts when the light comes on. The OP hasn’t specifically stated that there’s a charging problem. Just that the light comes on. The other suspect thing is where he’s getting these alternators from. Hopefully not Autozone or Orielly.
     
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  5. Mar 25, 2020 at 9:07 PM
    #5
    b_r_o

    b_r_o Who run Barter Town?

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    check battery to frame ground(s) closely, check positive cable between alt and battery. Are they loose? Pull them around with your hands. Use a meter to check for a large voltage drop from one end of the cable to the other. For example, electrically, there should be no difference between the positive terminal of the alt and the positive terminal of the battery. Same with the battery ground cable.

    Looking at the diagram above, terminals IG and S should have 12 volts, pretty sure L should too. Probe the connector and make sure the 12 volts doesn't flicker or go away. Wiggle the harness with your hands, flex stuff around..

    Do all this stuff with the engine running
     
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  6. Mar 26, 2020 at 2:06 AM
    #6
    Crippler25

    Crippler25 [OP] Member

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  7. Mar 26, 2020 at 2:08 AM
    #7
    Crippler25

    Crippler25 [OP] Member

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    The first thing I checked with the alternator was the plug with the 4 wires. I disconnected the ground sanding and cleaning it up because the copper had green corrosion. I still need to cut back the tape and black conduit that covers the wires from the plug to see if perhaps there may be a bare wire
     
  8. Mar 26, 2020 at 2:11 AM
    #8
    Crippler25

    Crippler25 [OP] Member

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    I purchased the alternators from a local auto parts/speed shop A&A Auto Parts. They carry remaned Remy alternators. I apologize because the alternator is not charging the battery correctly. I thought possibly a bad ECU. I will defintely try all of your suggestions today and post what the prognosis is fellas. I appreciate all of the ideas and input
     
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  9. Mar 26, 2020 at 3:53 AM
    #9
    Too Stroked

    Too Stroked Well-Known Member

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    The corrosion you found and removed will definitely add resistance to the circuit. Unfortunately, although sanding it removed the corrosion, it also removed any remaining plating - which is there to prevent corrosion. That means it will come right back.

    I have had decent luck with the product below to prevent corrosion in electrical connections - specifically light bulb sockets. It might buy you a little time.

    https://www.zoro.com/truck-lite-co-...VtESrkm5JNSNpObr9gNBE7Yezi5OfEoMaAtJNEALw_wcB

    The only true long term fix in this situation is to replace the offending wiring and connectors.
     
  10. Mar 26, 2020 at 6:50 AM
    #10
    Wattapunk

    Wattapunk Stay lifted my friends !

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    Do as others have suggested. Make sure the battery terminals are tight and sparkling clean. Check the condition/connectivity of the alternator wire and nut to the fuse box(wire with green marking on bolt):
    [​IMG]
     
  11. Mar 26, 2020 at 8:52 PM
    #11
    Jimmyh

    Jimmyh Well-Known Member

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    Now we know why the Battery Charge Light is on. If it isn't charging the light should be on.

    This is important: Using a voltmeter, What is the voltage reading at the battery when the engine is running?

    I wouldn't take an aftermarket rebuilt alternator if it was free. I have seen people go through 4 or 5 rebuilt alternators before getting 1 that sort of works.

    I wish you well in your quest. I think the issue is the "rebuilt" alternator(s).
     
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  12. Mar 26, 2020 at 9:04 PM
    #12
    TnShooter

    TnShooter Well-Known Member

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    Take these guys advice on the Rebuilt piece.
    For some reason, aftermarket and rebuilt ones seem to have a really high failure rate.
     
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