Voltage drop at ballast resistor
The amp meter fluctuations have occurred for some time now.
What do you mean fluctuations?
Lets take a minute and briefly go over Amps and Volts.
Volts are potential energy. Like water in a big holding tank on a roof, even when the electricty is not flowing, it has potential to flow. Same idea with a battery.
Amps are a measurement of flow. If a tap at the bottom of that water tank is opened, the flow coming out into a hose can be described in gallons per minute. If we punched a big hole in the tank, so much would come out it would knock down anyone trying to stop it from reaching the ground. Note it was the flow from 14' above the ground that knocked the guy down, not the height of the water sitting in the tank.
The ammeter shows how flow is making its way from the battery to the main junction, or how much current is flowing to the battery to charge it.
While starting the engine, the ammeter should show discharging to power the ignition, and the starter relay.
As soon as the engine is running, the ammeter should show charging of the battery. As the battery charges, the meter will show less and less current until the battery is fully recharged.
Thank you but can I get specific locations on the relay and bulkhead?
Pretty easy. On the Battery Positive post there are two cables. The big one leads directly to the starter. The smaller one, 10 or 12 gage, probably red, goes to a stud on the starter relay. Joining it there is main wire to the bulkhead connector - follow that to the bulkhead (in that wire will be a smaller gage wire called a fusible link).
The diagrams here will give you a general idea of what to look for.
Understanding Charging Systems with Ammeter
A '72 shop manual will get you the exact wire colors and cavities of the bulkhead terminals.
