Question about Ford Thunderbird

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Why alternator don't charge on a 1979 ford thunderbird?

The engine is a 8 cylinder 1979 ford thunderbird the alternator want charge unless i connected a jumper wire to the postive post battry and to the field wire on the regulator and when i do that the alternator will start charging like 13.8 volts at idle why the charging system don't work unless i connect a jumper wire from battry to field on regulator is the alternator bad or the regulator bad? the alternator and regulator been replace new please help.

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If you can use a new wire and they charge the battery then most likely you have a broken wire in the harness that runs between the alternator and the regulator.

Posted on Jun 10, 2017

  • 7 more comments 
  • Joe Russell Jun 15, 2017

    i check the field wire that run from the alternator to regulator its not broke what i need to check now?

  • Jerry Ross
    Jerry Ross Jun 16, 2017

    Ensure the battery post are clean and tight and your connection coming out of the regulator to the battery is clean and all connections are tight. in addition, check your ground wires and make sure they are clean and tight.

  • Joe Russell Jun 17, 2017

    i check the wires and battry post they look good still no charging what i need to check now how do i test the alternator and voltage regulator?

  • Jerry Ross
    Jerry Ross Jun 17, 2017

    Is the voltage regulator ground good? To test them you can take them to autozone or a good parts store and they will test the parts for free. This really sounds like a grounding issue. But just a guess as I am not there.

  • Jerry Ross
    Jerry Ross Jun 17, 2017

    Is this on a 12 volt positive or negative system. On negative system you have to tickle the regulator to get it to start and it has been so long since I used that I have forgotten just how to do it.

  • Joe Russell Jun 17, 2017

    the regulator is mount under the hood on the right fender it look like it is ground good but i unbolt the regulator and connect a jumper cable to the negative side of the battry and to the regulator body still no charge unless i connect a jumper wire from regulator field to positive side of battry then the system will start charging what that sound like to you? i don't understand what you mean about 12 volt positive or negative system please explain that?

  • Joe Russell Jun 24, 2017

    i check the wires between alternator and regulator i didn't find any broke i done replace the alternator two time the regulator look like a electronic one how do i check a regulator what else i need to check? when i connect a jumper wire from regulator field to postive post on battry the charging system start working.

  • Jerry Ross
    Jerry Ross Jun 28, 2017

    Did you get the answer I sent to you about checking the ignition wire going to the alternator.

  • Joe Russell Jun 29, 2017

    yes i got your answer,
    i check the wires between alternator and regulator i didn't find any broke i done replace the alternator two time the regulator look like a electronic one how do i check a regulator what else i need to check? when i connect a jumper wire from regulator field to postive post on battry the charging system start working.



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