Question I just finished completely rewiring a 1949 Chevy pick-up. Everything seems to work fine except now when the ignition switch is on the generator turns by itself. Current flowing backwards and turning it into an elec. motor? Any ideas?
Answer Somewhere along the line you have ignition voltage getting to the "A" armature terminal on the generator. Disconnect the three wires at the voltage regulator. One should be hot with the ignition off. That would be one of the heavy wires and it should have been connected to the "B" battery terminal of the regulator. Again this wire should be alive all the time. The small wire on the regulator should be the field wire and it should only run from the "F" terminal of the regulator to the "F" terminal of the generator. There should be no other wires connected to either terminal. And the wire connected to the "A" terminal of the regulator should be connected to the "A" terminal of the generator and there should be no other wires connected to this wire. Now back again to all the wires disconnected from the regulator. Turn on the ignition and retest. There should only be voltage at the "B" wire. If there is any voltage on any of the other two, then you have some wires crossed up. If the generator tries to motor all the time the problem is probably a defect in the voltage regulator.
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Thanks so much. I followed you lead and it seems to have worked perfectly.
All automotive including antique and collectible. However if the car has been modified I can only answer in general terms and maybe get you pointed in the right direction.
Automotive tech instructor.
Syndicated auto columnist 1970's though the early 1990's.
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Auto instructor for the following companies:
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Basically Franklin Technical Institute in Boston, Northeastern University, Fitchburg State Teachers College, Tufts University, and a lot of factory schools along the way.
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