with the engine running, try measuring the alternator output voltage right at the back of the alternator. You could have a poor/broken connection
between there and the Isolator.
I'm confused how you are measuring the voltages on Pins 1 & 2.
You said in your original posting:
"New development with what is happening. 12+ volts (battery state of charge) at the 12ga. wire. With ignition on I have .2 volts less than battery
charge on resister wire. When I plug into ports 1 and 2 voltage drops to 4 volts on resister wire and no output from alternator when engine is
started."
And in your last post:
"With the key on but engine is not running, when I plug the apc into the #1
& #2 ports of the alternator is when I get the voltage drop"
So it seems to me that you might be measuring the voltage BETWEEN pins 1 & 2. You should be measuring all voltages on the alternator with your
negative lead on GROUND (the case of the alternator or the engine block).
Pin 2 is the battery reference feedback voltage. It should show battery voltage whether or not the key is ON
Pin 1 is the excitation voltage (resistor wire). With key OFF it will be Zero volts. With Key ON you should read something less than battery voltage.
I've never seen a spec for this voltage, nor have I measured it myself, but the GEN light is wired in parallel with the resistor wire so I suspect
there needs to be about an 8 volt drop across the resistor wire to get the GEN lamp to light brightly... so maybe about 4 volts there is right.
You mention the APC. The APC simply adds a diode in series with the resistor wire (pin 1). It also adds an additional pair of connections which can
cause issues. Measure the voltages on both ends of the APC. Pin 2 wire should read battery voltage on both sides of the APC. Pin 1 wire should read
0.7 volts lower on the end plugged into the alternator (key ON). Try removing the APC to eliminate that as the problem.
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that