Denver,
Thanks for the great explanation. I think I got it
1) Positive voltmeter lead to black wire on regulator, Negative lead to a green wire on regulator. Engine 3000 RPM. This is the actual voltage the regulator "Thinks" it is sensing from the battery. If this reading is more than 14.5 volts I'd say to replace the regulator. Because a connection issue of any sort on the positive OR negative side would read LOW voltage, correct?
It would result in a low voltage on the black wire where the regulator measures system voltage. The voltage regulator will adjust the main output voltage on the RED wires (these go more or less straight to the battery + terminals) until it "sees" 14.5v on the Black wire, which comes from the ignition switch. But if there's a voltage loss in the black wire circuit, this would cause a drop in the voltage the regulator sees, and it will crank up the output going to the battery until there's 14.5 volts on the black wire again. This can result in overvoltage at the battery. Very easy to have a voltage loss on the black wire, this circuit supplies the ignition, lights, fan, goes thru various connectors and the ignition switch itself. For every volt lost on the black wire, you get an extra volt pumped to the battery. If the voltage regulator is defective, you can see MORE than the 14.5 volts on this measurement, telling you the voltage regulator is not doing its job.
2) Positive lead on voltmeter to Green regulator wire (check both), negative lead to battery Neg terminal. Engine 3000 RPM. High voltage readings here (more than 0.25 volt) indicate deficiencies in ground connections, either the green wires or the battery Neg cable itself. Make sure battery neg cable is in top shape (both ends), Could add another ground connection to the green wires.
Because if resistance is low there will be no flow of power through the meter. Path of least resistance is right to ground, correct? Measuring between green wires and battery Negative post checks BOTH ground connections at the same time. What we are checking for is any resistance that shouldn't be there. If there's some resistance in the green wire connections to ground this results in a small positive voltage being seen at the regulator's ground, offsetting what it measures at the black wire, and causing it to output a corresponding increased voltage to the red wires.
3) Negative lead on voltmeter to Black regulator wire, Positive lead to battery Pos terminal. Engine 3000 RPM. Voltage readings here indicate voltage drops thru the ignition switch and associated wiring to the regulator voltage "sense" input. A high reading here (more than 0.25 volt) is most easily fixed using the mod shown in post 13.
Same as #2 reason. That is if all connections on the positive are good the power would not want to go through the meter when it can go directly to the zener diode, correct? No, what we are measuring is how much voltage is lost along the way from the battery + post to where the voltage regulator is measuring it. Any resistance on this circuit plus accessory load on this circuit can cause voltage losses. As stated, the voltage regulator will just crank up the output until the voltage on the black wire is "correct". Nothing to do with what passes thru the meter.
Add the readings from step 2 and 3 and this is the amount of "overvoltage" at the battery caused by wiring connections.
Adding the total voltage drop on the positive side plus the voltage drop on the negative side equals total voltage drop, correct? Exactly. And this total voltage drop will be that many volts LESS seen at the battery after the voltage drops are corrected.
Below is the schematic I used. I believe it is less comprehensive than your method as it will tell you if there is an issue, but not necessarily where the issue is. Failing this test does not have to mean the regulator has failed etc.