Yet Another Charging Issue Thread - '70 240z

[Colin240z]

Hi guys. First off - a preliminary thank you for any help.

I have done some pretty extensive searches on 240z charging issues, but after some testing, checking, and connection clean-up, am still having an issue. I do have a multi-meter, but I'm a bit electrically challenged :paranoid:

Here's the scoop:

1. Voltage across battery at running idle is ~12.7V - not enough, which tells me something is up with the charging system

2. I'm not quite sure how to read the voltage the alternator is putting out with my multimeter, but with the neg of the multimeter grounded to the block, and the pos side hooked to the nut on the alternator - it read between 20 - 22...jumping around. Is this too much? I did have the alternator tested at Autozone - they said it passed.

3. I tried 2 voltage regulators (mechanical and solid state) with no luck. Again, not sure where to check/verify voltage. I attached an image - what is the wire on the side of the VR - is this a ground? It is routed into the harness

Some notes/questions:

- In various searches I have seen that the alternator or battery may be suspect. I am fairly confident the battery and alternator are good, as I've checked a couple, all with the same result

- The voltage regulator's 6 prong connector has 6 wires, whereas the six prong connector coming from my harness only has 5 wires. Is this right?

- I cleaned connections - no luck

- Is each component (Alt, VR) grounded? I would assume the ground is routed into the harness? As a test/verification, is it possible to disconnect these grounds, and run grounds to the block?

Thanks so much for any help. I am at wit's end and may have to give it up to a professional. I will be bringing the Z in to a Firestone place to have an AVR check done within the next couple days. I would like to learn a little bit though in the meantime. I am eventually planning on doing the 280zx alternator upgrade, but I do want to sort out the stock set-up first.

Many Humble Thanks,

Colin

[DeesZ]

The part that you are questioning is to the best of my knowledge a condenser intended to eliminate radio interference from the VR. Part number 27984-80700, all same up to 07/73 mfg. Someone else please chime in here, but I do not think that this would have any bearing on your charging. I will shortly post the testing procedure for the alternator for you....

[DeesZ]

From the FSM... Pg. EE-18 & EE-19. I hope that this helps.

For some reason I am suspect that the battery needs a full charge or may be failing.... But this should help with your diagnostics. Post mere as you learn.

[/ATTACH]