Cranks but won't start. Unplug ground at field spade on Alternator and it starts?
The alternator is the power supply that runs at higher voltage. Without the magnetic field power, the alternator doesn't generate anything and the battery takes over as the power supply.
15.2 to 15.4 indicates there is some slight resistance between the alternator and battery, and probably significant difference between the alternator and regulator.
Lets put the information you collected onto the drawing.
Engine running, battery recharged.
Voltage is high causing an overcharge situation.
Voltage at the regulator's Ign input is probably 14 to 14.9 Volts.
The alternator is supplying a minumum of 7 amps.
So we can conclude that the R6 connector at firewall is not the primary source of resistance.
Now the other test, engine off, key in run.
With the Unlilte connected there is 1.3 V lost between the battery and the ballast resistor.
Field current has been measured previously with engine running. It will be a little less when supplied with 12 Volt power.
Current through coil is probably around 2.5 amps with ignition on.
Unilite draw is unknown but significant.
Therefore
There is probably significant resistance between the feed to the key switch and the connection at the ballast resistor.
It is probably before the connection at the regulator because the alternator is supplying at over 15 Volts even at relatively low loads.
Hope that helps.
That all makes sense, right?
The alternator is the power supply that runs at higher voltage. Without the magnetic field power, the alternator doesn't generate anything and the battery takes over as the power supply.
15.2 to 15.4 indicates there is some slight resistance between the alternator and battery, and probably significant difference between the alternator and regulator.
The difference here is current. With the Unilite plugged in, more electrons are trying to get past the resistance. Since the power is coming from the car's battery the increased current with the Unilite plugged will be indicated. it should take quite a bit more current to cause a .5 V increase in votlage drop.
Lets put the information you collected onto the drawing.
Engine running, battery recharged.
Voltage is high causing an overcharge situation.
Voltage at the regulator's Ign input is probably 14 to 14.9 Volts.
The alternator is supplying a minumum of 7 amps.
So we can conclude that the R6 connector at firewall is not the primary source of resistance.
Now the other test, engine off, key in run.
With the Unlilte connected there is 1.3 V lost between the battery and the ballast resistor.
Field current has been measured previously with engine running. It will be a little less when supplied with 12 Volt power.
Current through coil is probably around 2.5 amps with ignition on.
Unilite draw is unknown but significant.
Therefore
There is probably significant resistance between the feed to the key switch and the connection at the ballast resistor.
It is probably before the connection at the regulator because the alternator is supplying at over 15 Volts even at relatively low loads.
Hope that helps.