72 Maverick won't charge

Discussion in 'Technical' started by Hairy W Bush, Jun 14, 2017.

  1. Hairy W Bush

    Hairy W Bush Member

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    -Alternator tested good. [tested twice]
    -new battery
    -new voltage regulator pigtail
    -fairly new voltage regulator
    -power to alternator
    -car dies when + terminal is removed
    -jumped A&F on regulator connector, brought RPMs up some, no voltage change
    -no power from F terminal when car is running
    -getting power to headlight switch, but no headlights, just tail lights.
    -no fusible links burnt or blown

    all signs point to alternator but I'm stumped.
     
  2. Krazy Comet

    Krazy Comet Tom

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    With your tests, if it doesn't have a open fuse link between alt and battery post of solenoid it should be charging(assuming alt is OK)... Grounding the regulator F terminal should put it into full charge mode...

    No headlights is probably a bad switch... Those have two internal circuit breakers, one for HL other for park/tail lamp circuit that are prone to failure...

    If there is no power at the R/Y wire at switch, it's bad... I'd check first at the dimmer switch, can fail and loose high and/or low beams...

    [​IMG]
     
    Last edited: Jun 14, 2017
  3. Hairy W Bush

    Hairy W Bush Member

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    and even if the switch is bad it should still charge correct?
     
  4. Krazy Comet

    Krazy Comet Tom

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    Yup, the HL switch has nothing to do with charg...

    Does it have a operating alternator light??? The circuit that turns on lamp also excites the alt, if there was a broken wire somewhere that could be your problem...
     
  5. Hairy W Bush

    Hairy W Bush Member

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    I forgot to mention that, no ALT light on.

    I just pulled the cluster (i have a diagram and I thought the light green/red and black/light green wires went to switch)
    and located the light green/red & black/light green. With the key ON, I get power to both wires, so no light. why am I getting + to both?
     
  6. Krazy Comet

    Krazy Comet Tom

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    If the negative side of bulb circuit is open 12v will be on both terminals, thus it won't light...

    If regulator I terminal has voltage with sw on, then there is a problem with regulator or maybe wiring...

    Check this out... http://1bad6t.com/Maverick/repair/engine_repair_02.html#c
     
  7. Hairy W Bush

    Hairy W Bush Member

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    thanks for the link. so to get this straight, if the bulb to the ALT light burns out, the car won't charge? wow, bad design
    anyway, with the key switch ON, there is no voltage at the I on the regulator

    according to the diagram, the negative side on that bulb ties into a BLK/LITE GREEN wire that goes from the flashers, to the ignition switch.
     
  8. Krazy Comet

    Krazy Comet Tom

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    Yes it will charge without the lamp, that's a old wives tale that just won't die... There is a parallel 15 ohm resistor(actually resistance wire) across bulb that provides excitation if bulb were to fail... If resistor fails it probably won't charge even if bulb is good... At least if it had a mechanical regulator...

    No voltage on I terminal may be tricky... It's should be grounding lamp to complete that circuit, so it isn't supposed to have voltage(at least only a volt or two)... With ign on if it will turn on a test lamp that's connected to battery +, then it's doing it's job... If not regulator may be kaput... Since that point is far end of lamp ground circuit, there is apparently a open somewhere between bulb & resistor and the I terminal... Grounding I terminal on plug with it disconnected from regulator should turn on light if wiring is OK...
     
  9. Hairy W Bush

    Hairy W Bush Member

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    my flashers don't work....could that be the 'open'?
    edit: that's different than the Hazard flash. confused what the difference is
     
  10. 71gold

    71gold Frank Cooper Supporting Member

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    you have two flashers...one for the turn signals and one for the Hazard lights flashing.
    make sure everything has a good ground where it mounts to the car.
     
  11. Hairy W Bush

    Hairy W Bush Member

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    oh yea I know now. I disconnected that flasher and no change. I guess I'll look more later today
     
  12. Hairy W Bush

    Hairy W Bush Member

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    I don't see the resistor. What I do see [on my wiring diagram] is a dot where the black wire goes to. so that's either a ground or the resistor itself. I can't find it and it's tight going into the wiper switch corner of the dash + the pedals

    edit: found this, but the colors are throwing me off. the 1 wire end is BLK/LITE GREEN and so is one of the other end of the connection, but then there's BLK/BLUE
     

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    Last edited: Jun 15, 2017
  13. Krazy Comet

    Krazy Comet Tom

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    The resistance wire is part of harness... Colors to resistor are either red/green or green/red(I believe resistor wire is green)... Problem is there is one for ignition, another for charging and are opposite colors... In my Comet the resistance wire connects to the charge light wire at the firewall connector plug... I remember chasing it when I was wiring for a internal regulator 2G alt... For those the light will glow only dimly if resistor isn't increased in value...
     
  14. Hairy W Bush

    Hairy W Bush Member

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    where is this at? I only see disconnected connectors on my engine side of the firewall. also what did I take a picture of? it looks like a blown fusible link. this wiring has me confused
     
  15. Krazy Comet

    Krazy Comet Tom

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    Resistance wire is in dash harness, not under hood...

    Go back and read my post in #8, perform the tests...
     

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