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New alternator not charging at all

Posted by paintball4fun21, Apr 18, 2011
Electrical Tech - Wiring, turbo timers, electronic boost controllers, gauges, fuses, wiring harnesses, wire tucks, car audio, and all other electrical component discussions.

  1. paintball4fun21

    paintball4fun21 Proven Member

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    onalaska, Wisconsin
    I have tried 3 brand new alternators and my car is not charging at all. Im measuring it from the alternator positive terminal (and also from the battery). As soon as I turn on the car the voltage starts to drop from 12V. Everything is hooked up right and the belt is not slipping.
    I have tried~
    -Re wiring it
    -checking the alternator fuse
    -adding grounds
    -it has a new battery
    no luck
    Im thinking it has to be one of the wires from the alternator pigtail connection, since the alternator is good but is not putting out anything at all. How can I go about following these wires or checking for a short in them or something?
     
    #1
  2. paintball4fun21

    paintball4fun21 Proven Member

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    onalaska, Wisconsin
    anyone?
     
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  3. 1990AWD

    1990AWD Supporting VIP

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    Langham, SK_Canada
    If your worried about the wires not having good contact, measure voltage directly at the terminal on the alternator and at the battery. The difference should not be more than .5V. If it is, you have a bad connection causing high resistance.

    Also, if you don't have 14.5V at the alternator, the voltage regulator is to blame.

    Remember if the car runs but always needs a boost, it's typically the battery. If the car starts but will not continue to run, its typically the alternator.
     
    #3
  4. paintball4fun21

    paintball4fun21 Proven Member

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    onalaska, Wisconsin
    Charged up the battery today fully again. It reads 12.75 volts when turned off. When turned on it reads 12.34 volts at the battery and alternator. Again this is my 3rd brand new alternator being tried(so im sure the alternator is good), and the fuse is not blown. I have no idea what this could be! Could the pigtail harness connector, that plugs into the alternator, actually make it not charge? as I said no fuses seem to be blown
     
    Last edited: Apr 20, 2011
    #4
  5. ziggo0

    ziggo0 Proven Member

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    La Porte, Indiana
    I'm back in the same boat too. I noticed it randomly will start chargin while driving but not at idle or anything
     
    #5
  6. ziggo0

    ziggo0 Proven Member

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    La Porte, Indiana
    To update you, last night I yanked my whole wiring harness. Found no shorts in the 4 plug connector, the wiring from the alt. positive terminal to fuse box to battery checked out good, 'charging/battery' light checked out good, relay works. I replaced all my ground wires with 4g wire. Block to body, body to battery, battery to block.

    Even after all this the alternator still would not work. I guess sitting for half a year killed it. It is an OEM alternator that showed no 'dim dash lights' it simply just wouldn't put out voltage.

    I had a spare 'duralast' alternator sitting around that I popped in there. Dash lights were dim, battery/brake/coolant - but the odd thing is, if i reved to 3.5k rpm 1 time, the alternator would kick on and stay on till I shut the car off. WTF is with these cars.
     
    #6
  7. paintball4fun21

    paintball4fun21 Proven Member

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    onalaska, Wisconsin
    yea im still trying to deal with this problem. I know the alternator is good and the battery, and the power wire going to the fuse box. also all the fuses look good. I have no idea why my alternator is not charging the car. this is terrible, cant figure it out

    I fixed my issue tonight! It was the alternator relay under the air intake/coolant overflow. The relay had a wire broken off and it was corroded. I ended up cutting the wires and put spade connectors on them to connect to the relay(after i wire brushed the corrosion off). works great charging at 14.5 volts at idle now!
     
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