OK the early (pre 70) charging system is dead nuts simple You have power from the key, known slang as "ignition run" or IGN1 which goes through the bulkhead connector and supplies everything under the hood for engine run, ignition, power to the voltage regulator, the alternator field in 70/ later, electric choke in later years, etc etc
So the VR/ alternator field circuit is simple. The dark blue "run" line branches off to feed the VR IGN terminal. The VR MUST BE GROUNDED. The field terminal feeds the green wire which goes to the alternator field --through the field--and to ground. This countrols charging.
The alternator is grounded by bolted to the engine, and the output stud comes off--feeds (BIG BLACK) through the bulkhead connector, to the under-dash welded splice where it branches off to the fuse panel, the ignition switch, and the headlight switch----goes through the ammeter---comes out through the bulkhad connector on BIG RED---through the fuse link---to the big starter relay stud---and to the battery
Simplified diagram of power distro:
Catalog
View attachment 1715763397
Simplified diagram of the VR/ field:
View attachment 1715763398
SO-------------some simple tests:
I "sort of" divide the problem into 3 areas---
1.....The VR/ field circuit
2.....The output / ammeter circuit
3.....The major components, here mostly the alternator and VR
1...Disconnect the green field wire at alternator. Rig a jumper wire from that alternator terminal direct to the battery. If possible, get in subdued light and connect/ disconnect it and watch and listen for a small spark which will tell you the field is drawing current. Don't sweat that. Start engine with voltmeter connected direct to battery. Run RPM up simulating cruise RPM and see if battery voltage climbs at all.
2....If no change above, now you want to see if alternator is possibly "putting out" but maybe the charging wire circuit is open. So now move your voltmeter to the alternator output stud and re-run the test. If no output change, the alternator is not charging.
3....One thing you can do is to pull the alternator and remove and inspect brushes. Look for excessive grease/ mud/ other that would cause brush sticking, or severe brush wear or other problems that would prevent brush contact
If this test shows no charge, you either need to fix or replace alternator
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If the above tests DID result in output to the battery, now we need to concentrate on VR and field wiring.
4..To check the wiring, reconnect the green field wire in tests above, and disconnect both wires at VR. Rig a way to jumper these wires together, which will do same thing as first test--that is "full field" alternator---except now we are using the complete harness. If the thing charges, that wiring is intact.
Next remove and inspect grounding on VR. Looseness, stripped bolts, rust, etc, clean around bolt holes remount tight with star lock washers. Reconnect VR and retest. If it will not charge, but did so in last test (4) when jumpered, then replace VR
Obviously if test (4) does not charge, but the earlier test (1,2) did, you have a wiring harness problem.
