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I have a new alternator and new batteries and the batteries will drain over night when I charge them and start it runs fine for a little while but alternator isn't charging the batteries. Any help would be greatly appreciated
 

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When the key is placed in the Wait-to-Start position, does the battery light illuminate? Anything new installed lately (aside from the batteries and alternator) like a glowplug relay or other electrical work? Cheers!
 

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The alternator requires 12 volts on both of the wires in the control plug -- one is hot all the time and the other is with the key -- this can be checked with a test light or volt meter
 

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I would check to make sure the bulb is good and the wiring is good for the bulb. The alternator needs a good bulb to provide voltage to the field windings in order to charge. If the field is not initially energized the alternator won't charge. That doesn't take into account any draw that might be draining the batteries. I've attached a diagram of the charging system. Cheers!
 

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If you ground the LG/R wire at the alternator connector with the key on ..the light should come on .. that is the charge signal wire
The V/W is hot all the time from the battery
 
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