Evening all ... i got a michigan L70 with a charging problem being so similar to the L120 im able to swap alternators and its not the problem ...I have new batteries and have traced the wires from batterys to starter to alt cleaned them all but i dont have a diagram after ... All im reading on fluke meter is battery power and slowly dropping 24 volts swapped the alternator to the l120b and 27.6 to 28 volts so its not alternator or batteries .. the fuse panal at front is in rough shape as far as diagram and ive checked fuses and changed a couple relays but still 24volts and dropping.. its a 3 wire alt batt , ground and white wire same as 120b but its grey not white ... please help if youve had these problems or have a diagram i can access...thanks
one thing ive learned about my L70's electrical system is that it always involves a relay of some sort.
Have you put a meter on the Batt stud on the alternator and verified it has 24V on it? Have you checked that gray (white) wire has voltage on it when engine is running?
Might seem like a dumb question but...When you turn the key to the ignition position does the alternator light come on in the dash? If not replace the bulb, alternator will never charge without field current. I'm betting the grey/white wire is field.