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Alternator is bad?

Discussion in '2nd Gen. Tacomas (2005-2015)' started by Will Ennis, Nov 30, 2015.

  1. Nov 30, 2015 at 10:14 AM
    #1
    Will Ennis

    Will Ennis [OP] New Member

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    I'm new to this forum and recently bought a Certified Tocoma with 35K miles from a dealership in town. I drove is 6K miles and noticed the battery was getting weaker. I took it to Auto Zone and bought a new battery and had them test the alternator. It tested bad. Tech says its not charging the battery like it should. I called a dealership in town and they are telling me to bring it in to have the problem diagnosed. If the alternator is tested bad at the dealer then my warranty company should cover the parts and labor for a $50 deductible fee. My question is: are there any worries about the part they put in my truck? I've never heard of an alternator going bad after 41K miles on it. Especially in a truck with no modification ie: stereo, amplifiers, KC lamps, winch, etc. Any input would be greatly appreciated.
     
  2. Nov 30, 2015 at 11:54 AM
    #2
    username

    username Fluffer

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    I broke an alternator case at around 50K miles, but mostly because it was submerged in mud and ingested some rocks/mud, bound up, and the case gave out. However, it still worked! I would suspect the high school drop outs working at auto zone don't know what they are doing. Go to walmart and get a multi-meter and see how many volts are at the battery terminals. Should be around 12.8V at rest, and near 14V when it's running. Most Tacoma's run around 13.8V at idle. Here is how the dealer does it, you can check it yourself very easily. http://www.customtacos.com/tech.old...f/06toyrm/06toypdf/06rmsrc/rm2006ta/02400.pdf
     
  3. Nov 30, 2015 at 4:03 PM
    #3
    devkurf

    devkurf Member at Large

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  4. Dec 1, 2015 at 5:03 AM
    #4
    Lester Lugnut

    Lester Lugnut Well-Known Member

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    A simple way to test an alternator is to put the positive(red) lead from a voltage-ohm meter on the "B" terminal of the alternator. That's the "battery" terminal. Put the black lead from the VOM on the alternators case(ground). This of course is done with engine idling and everything off. Use the 20 setting on the DC voltage scale. If the motor is cold, you should see between 13.8V-14.2V. If it's warmer, you may see something around 13.4V

    The "B" terminal on the alternator usually has a round rubber plug over it that peels off by hand.

    Given that I have zero faith in car dealerships, I wouldn't be surprised if they replace your original Denso alternator with a POS from Auto Zone or some other mass marketer.
    Whenever mine bites the dust, I remove the alternator myself and take to a local electrical rebuilder. Just sayin'...
     
  5. Dec 1, 2015 at 10:07 AM
    #5
    george3

    george3 Well-Known Member

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  6. Dec 1, 2015 at 10:21 AM
    #6
    Lester Lugnut

    Lester Lugnut Well-Known Member

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    george3:

    Answer to 1st question - I have more than 1 vehicle

    Answer to 2nd question - Placing the VOM leads on the alternator tests the alternator. Placing the VOM leads on the battery can give indication that the alternator is good, but testing the alternator itself is the best way to test that device. During my recent alternator issue('06 Avalon) - the battery was reading 12.3V with a cold engine. To be absolutely sure the alternator was the issue, I needed to test it. Had the alternator reading been good and the battery reading bad, I would have been looking at a bad battery.

    Pulling an alternator off a Toyota 2GR-FE engine('06Avalon) is a bit more of a pain than a Toyota 1GR-FE engine(Tacoma). The 2GR-FE is transverse mounted.
     
  7. Dec 1, 2015 at 10:28 AM
    #7
    george3

    george3 Well-Known Member

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    Thanks for the reply.
     

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