Ramcharger electrical troubles

You can test the alternator--which is the best way--on the vehicle, as you can also see if it's actually the alternator or VR or the wiring

I tend to divide the charging system into "rough" sections, no particular order
1....The output circuit wiring. This is the entire path of the heavy charging circuit from the alternator to the battery
2...Field/ VR wiring. This includes the power supply to one field terminal from the key, the wire back to the VR, the VR ground, and the power (blue) coming from the key to the VR
3...VR
4...Alternator

A...HOW TO "full field" test the alternator and output circuit
Disconnect the VR (green) at the one alternator field. "Rig" a jumper---wire with a 1/4" spade/ flag terminal to fit the field terminal, or an alligator clip jumper. Jumper the terminal at the alternator which had the green to ground.
Turn on key to "run." Measure OTHER (blue) wire terminal with the blue connected and the formerly green terminal grounded. You should have 12V or close at the blue.

Start engine, while monitoring battery voltage, slowly bring up RPM and see if system charges and if battery V starts to "come up." If it does keep RPM/ voltage below 16V

If no good result, move meter from battery to the alternator output stud. If that voltage goes quite high, say more than 2V higher than battery, then you have an open or very poor connection in the path from the alternator output to battery

If the above works, now check out the VR and VR wiring.

B....Reconnect green wire to field, disconnect blue wire. Ground the alternator field terminal formerly connected to blue to ground

"Rig" a way to jumper across the two VR connector terminals. Small machine screws work for this with a jumper wire. Turn key to "run" and measure green wire terminal at alternator, with everything connected as described. You should have 12V at green wire.

Now run engine as before, and see if it charges. If so, the VR path is healthy

VR. Make ABSOLUTELY CERTAIN that VR is grounded. Scrape around mounting bolts on firewall, and front and back of VR. Remount with star lock washers. Make CERTAIN you have a good jumper between engine block or battery and the body/ firewall.

"Work" the VR connector in/ out several times to "scrub" the VR terminals and "feel" for tightness. Examine the inside of the terminals with a strong light for corrosion/ damage. You can buy VR pigtails from such as NAPA

If everything above checks out and it will not charge, do a final "recheck" of the VR/ wiring. Start with everything wired "normal." Pull VR connector, and "rig" a jumper to ground from the green wire. Start, run, check for charge. If charging, recheck that you have 12V at the blue VR connector. If that is so, and if you are CERTAIN the thing is grounded---replace the VR

ALSO READ THE BOOK and look for the alternator field amperage test. It is possible that the alternator rotor (field) is partially shorted and drawing too much current---blowing up VR's