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I have a 86 dodge d100. It keeps blowing the main fuse from the alternator to the battery. I have a 100 amp alternator and a standard regulator. Do you think I need a bigger regulator. It only blows at high rpms.

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More testing and info needed. With the car stopped, how many volts at battery? With fuse out, how many volts at each terminal? With vehicle running, repeat previous measurements. What size fuse is popping? Answers to these questions will lead you in the right direction.

Posted on Nov 30, 2014

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  • leroy brayman
    leroy brayman Dec 02, 2014

    Stopped... bat 11.92 wo/fuse 11.92 .... . Running 14.01 wo/fuse 12.92 ......30amp fuse. Alt running..... pos to neg 14.89 green to neg 1.41 blue to neg 0 green to pos 13.50 blue to pos 14.92

  • jeff5may32 Dec 03, 2014

    From the above readings, it looks like the blue wire is not getting voltage to it while the ignition is on. This wire on the regulator serves as both a power wire for the module and a sense wire. Verify that this blue wire is dead when the ignition is off, and has battery voltage on it when the ignition is on. It looks as if you have lost your switched power source on the blue wire, forcing the volt reg to run flat out. Normal battery voltage while running is close to 13.8V, you are seeing almost 15V which will fry your battery. I suppose thids is why the fuse is blowing, to save the alt and battery from each other.

  • leroy brayman
    leroy brayman Dec 03, 2014

    I fixed that problem. . It still blows the fuse when I turn lights on. It dont with lights off.

  • jeff5may32 Dec 04, 2014

    which wire is the fuse in?

  • leroy brayman
    leroy brayman Dec 04, 2014

    the heavy wire from bat to alt. this wire only is connected at batery and alternator.

  • jeff5may32 Dec 04, 2014

    OK so you need to put in a #6 cable straight between them. For protection, use a #10 fusible link or 100 - 125 Amp fuse.

  • jeff5may32 Dec 04, 2014

    You shouldn't need a fusible link or fuse, but it's cheaper than an alternator if something goes wrong.



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