Charging Problem
 

I am trying to narrow down a charging problem. Does the alts charge both batterys all the time, or only when the batt switch is in certain postions. I finally checked my batterys with a snapon tester yesterday 12.3 volts at 2000 rpm it seem like the only way the batterys went above 12 volts was when the switches were in both. I guess I need to check right on the back of each alt and make sure I dont have some corosion on terminals before I start replacing alts. Does anyone have a charging diagram on the charging system does the charge wire run over to the starter wire? thanks guys

I had a problem like that once it was the negitive black cables were coming lose from the terminals check all wires make sure they are not coming lose