GM stopped using ammeters because 90% of the people that plunked down their money for a new car didn't know squat about how a car worked. It was easier to put in an idiot light, than explain that "0" on an ammeter was a good thing. Quite frankly, I think an idiot light is just as usefull as an in-dash voltmeter.
A (in-dash)voltmeter will not tell you the condition of the battery. It will tell you what the voltage regulator is doing. Any variation in voltage is going to be more temperature variations than anything else. Any of you stovebolters here know that you adjust a voltage regulator with a thermometer and a voltmeter. You can get a jump start if you have a bad battery and that voltmeter will say 14 volts all day and all the way home. Get a jump on a car with an ammeter and that meter will read high and never go down all the way.
A (in-dash)voltmeter will not tell you the condition of the battery, other than when it's dead. Let's see. Put key in slot, turn key, nothing, I wonder if my battery is dead, I better look at the voltmeter so that I know for sure.
If you are driving down the road and say a fan belt breaks. A voltmeter, a ammeter and an idiot light will all give you an idea of what that sound was.
Only an ammeter can give you an idea of what the battery condition is before it leaves you sitting.
When these trucks were built, the symbol for Voltage was "E". If a shunt wire in a ammeter is a low resistance load then what is a straight piece of copper wire? Just thought I'd ask.
The majority of ammeter problems are at the spade connecters in the firewall bulkhead plugs. It has nothing to do with the resistance going down. On a bad connection the resistance goes up. If the resistance goes up, the voltage drop goes up and the heat goes up. SMOKE.
