This seems good
This is at the green wire at the alternator and still connected? This measurement may not mean much
It might be possible
Alternator problems that is a "no charge" condition boil down into several areas..............
1...An open or poor connection in the charging line to the battery, especially in unmodified cars
2...bad alternator
3...Problems in the field wiring harness and connections
4...Bad regulator
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To start, determine if 1 or 2 is the problem. Take a clip lead, remove the green field wire from the alternator, and clip the alternator terminal which you just exposed to ground. With the key "in run" check voltage to ground at the blue connection. Do not unhook it, rather, "back probe" the connection. With the area in subdued light, and key "in run" connect / disconnect the clip lead. You should see a small spark. Start the engine, slowly bring up RPM while watching a voltmeter on the battery.
If voltage can be made to climb (keep below 16V) then the alternator is OK
If not..........double check that with key in "run" and the green wire grounded that you have battery voltage at the blue field wire. You can also check field current by putting your meter from the green wire field terminal to ground. Post brand and model (or a photo) of your multimeter if you don't know how
Also if not, check that the output wire to the battery is OK. With engine running as before, and clip lead installed, check battery voltage, and voltage at alternator output stud. If the voltage at both is the same, and low, the wiring is OK. But if battery voltage is low, and the alternator stud fluctuates a lot, going way high, above 15V then the output wire is open
If voltage DID go up, now your problem is in field wiring or the regulator. You've alreadly checked the blue wire. With engine and key off, use ohmeter to check disconnected green wire from alternator end to the regulator connector. Should be good continuity. That is the only place the green wire goes.
With regulator connector disconnected, and key in "run" check voltage at the blue terminal in the connector. Should be "same as battery." Inspect the connector. Work it in out several times off the regulator to scrub the terminals. Make SURE the regulator is grounded.
If it does not charge, replace the regulator
