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Thread: Not charging

  1. #1

    Default Not charging

    So I just replaced the alternator with a reman from advance, new battery as well. I boosted her and let her run for 20 mins or so and wouldn't start after that. I double checked the connections to the alternator and it all looks fine.

    What am I missing?

    Thanks in advance!

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  2. #2
    FEP Senior Member 87gtVIC's Avatar
    Join Date
    May 2009
    Whitestone, NY


    When you turn the key on does the batt light on the dash illuminate and then turn off? That light bulb needs to be in play and working for the alternator to charge the battery.

    I also dont know what car you are working on so I am going off of general 80's ford wiring for the charge circuit.

  3. #3


    You should have at least 12v at the battery when the car is not running. About 14.4v when the car is running. 20 minutes of run time should not have drained a good fully charged battery. Sounds like either a bad battery or something really dragging it down.

  4. #4


    Oh sorry. Its an 82 with 1G alternator. Brand new battery. Very minimal as far as accessories. No stereo even.

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  5. #5


    A new battery doesnt always mean a good battery, especially if it was drained to near zero once or twice. If so, its most lilkley shot.
    Auto Zone, Advance auto, Batteries Plus, etc, will do a load test on the battery for free.
    Always verify the basics before throwing parts at the problem.

  6. #6
    FEP Super Member gr79's Avatar
    Join Date
    Jun 2009
    SE Michigan


    Did it start before the parts change outs? Were they done because of a problem?
    Starter ok? Starter connections ok?
    Do the free checks at the auto parts stores if you can make it to one.

    Check all ground wires and connections, battery and engine.
    Jumper cables can be used as temp secondary ground cables to good known ground source on car body and engine.
    Repair style battery wire terminal connectors should be avoided if they exist.

    The connector at the voltage regulator can get cruddy and the terminals/connector dirty.
    Alternator connectors can go bad from age or fatigue. Can get dirty inside, have corrosion too.
    External regulators themselves last a long time but..
    Check starter solenoid wiring connectors. Make sure the regulator and starter solenoid are mounted tight to fender.

    If problem is deeper, check the wire harness from the alternator to regulator with a multimeter.
    No need to unwrap it.
    Key off, disconnect connector at voltage regulator. No power is needed to test the wires.
    Use long test leads as a bridge, connect to each wire end, at alt and v reg connector pins, per wire code.
    Verify wires (3?) are not damaged, shorted (burnt off insulation) or broken, and are conducting from alt to regulator.
    Wires are like house pipe plumbing. No leaks (short or corrosion) or broken pipe (wire) wanted.
    Damage can be hidden inside the wrapped wire loom. Happened to me.

  7. #7
    FEP Power Member Mustang Kid's Avatar
    Join Date
    May 2011
    Grants Pass,OR


    Had this issue on my 80 Fairmont, thought it was the alternator but it was the voltage regulator. Replaced it and it charged fine afterwards
    1982 Mustang GL two hatchbacks, 3.3l and 5.0l
    1983 Capri RS Black Magic Ttop
    1984 Capri RS Sunroof
    1984 Mustang GT 'Vert
    1985 Mustang LX SSP CHP 8337
    1985 Mustang LX SSP CHP 8362
    1985 Mustang LX 3.8l 'Vert

  8. #8
    FEP Senior Member Tigger's Avatar
    Join Date
    May 2009
    Portland Oregon


    When you jump it and it is running take a dvom and see if the alternator is charging. Then you will have a better idea where to start looking.
    67 Mustang Coupe
    96 Tangerine GT
    86 Saleen #179

  9. #9


    I'll replace the voltage regulator and check back in. Thanks guys!

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  10. #10
    FEP Supporter Broncojunkie's Avatar
    Join Date
    Jan 2015
    Barboursville, WV


    It was my understanding that the vr is always supposed to be replaced with the alternator. Having said that, did you have the new alternator tested? I always have the store bench test it before I pay for it. Quality control on some of this stuff is terrible and I've had several alternators, starters, and ignition modules bad right out of the box.
    79 Pace Car - 331, t5
    79 Cobra - working on 351w, t5
    86 coupe - rotbox roller
    86 coupe - working on 408w, c4
    88gt - 302 efi, t5

  11. #11


    Update. I replaced the voltage regulator. I found a black wire going nowhere so I figured it was a ground that had come loose. Bolted it to the frame and tried again. Same outcome. So I decided to pull out the multimeter, find some info on what all these wires should be doing, and start over. Turns out I'd inadvertently grounded the Stator wire that is mean to send voltage to the electric choke. I double checked and tightened the connections and just removed the STA lead.

    Now, it starts up and is charging under its own power. I was gonna just ditch the 1G and upgrade to a 3G but it's getting the job done so I'm good for now. And I learned a lot about the writing on this old tank.

    Thanks for all the replies guys!

    Sent from my LM-G820 using Tapatalk
    Last edited by Kelway76; 03-25-2020 at 09:51 PM.

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