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CHARGING SYSTEM PROBLEM 1975FJ40

Discussion in '40- & 55-Series Tech' started by cavsfj40, Jan 25, 2004.

  1. cavsfj40

    cavsfj40

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    Hello,
    I'M HAVING PROBLEMS FINDING THE REASON FOR A NEGATIVE AMMETER READING. ALL CHARGING COMPONENTS ARE NEW AND CHECK OUT TO SPECS. ALL WIRES SHOW CONTINUITY AND BATTERY IS AT FULL CHARGE. IS THERE A DRAW SOMEWHERE OR IS THIS PROBLEM LINKED TO ANOTHER SOURCE? VOLTAGE REGULATOR IS SOLID STATE UPGRADE AND WORKS FINE. FUSES ARE ALL NEW AND THEY DO NOT BLOW. WHEN I TURN THE HEADLIGHTS ON THE NEEDLE GOES FURTHER TO THE NEGATIVE. CAN ANYONE OFFER A REASON OR COURSE TO TROUBLE SHOOT THIS GLITCH?
    HELP,
    BOB
     
  2. wdorry

    wdorry

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    Did you check the wires on the amp meter. If they are switched it will read backwards. HTH Bill
     
  3. cavsfj40

    cavsfj40

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    thanks for the tip. unfortunately it was all working up until the other day when the alternator went out. fusible link is good and so is everthing else. i thought that perhaps the voltage reg was bad so i picked up another and the problem still existed. i have no other ideas
     
  4. Pin_Head

    Pin_Head

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    What is the voltage across the battery with the motor running above 1000 RPM?

    12V = alternator not putting out.

    14V and above alternator working. Did you rewire you charging system? If so it may not be wired correctly.
     
  5. lone gunman

    lone gunman

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    i had a the same problem in my 76 fj40, but mine ended up being my heater switch, my amp guage would go to the negative and with lights on and radio it was worse. i found that if i turned the heater off the short stopped, and if i turned it on and jiggled it the short stopped. i found the contacts in the switch were bad, so i took the switch apart and sanded the contacts down with a block and sand paper and have not had a problem since. something to try, hope it helps?
     
  6. arutgers

    arutgers

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    I would suspect the rectifier diodes in the alternator.

    Ton