Charging Problem

You need some basic tools. Not just for this job, but "because."

You need a spark tester, a 12V test lamp, a multimeter, and a few (at least two) alligator "clip leads."

Assuming you have the original 69 system, we can divide

a "no charge" problem into different sections.

Might be bad alternator

Might be bad VR

Might be charging output circuit harness issues (from output of alternator to battery)

Might be field wiring issues

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So let's dig right in with some simple tests

First, get to the alternator and remove the green field wire, it simply pulls off. Take your alligator clip leads and hook the alternator field terminal to a battery source, such as the big stud on the starter relay. DO NOT use the alternator output stud. We'll get to that

Start the car and slowly bring up RPM while monitoring battery voltage. Any increase? No?

Move your voltmeter to the alternator output stud, and repeat. Any increase?

If no, the alternator is not charging

If the alternator stud voltage goes "quite high" but the battery voltage stayed low, then the circuit path from the alternator output to the battery is 'broken' that is open.

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However in the above test, IF the voltage at the battery starts to climb, this means the alternator is charging, AND the wiring from the alternator output to the battery is intact.

Now, "is it" the field wireing?

REMOVE the VR. Unhook both wires. Jumper the two wires together, and reconnect the green field wire at the alternator. Repeat, run the engine, check battery voltage. Does the voltage still start to rise?

If so, this shows that the field wiring is OK.

NOW scrape clean the VR mounting base and the firewall, and remount the VR TIGHT with star lock washers. The VR MUST be grounded. Run the engine and see if it charges. If not, replace the VR