HELP! Cars not charging after 3 alternators.

[Pleadingbark]

My car suddenly has stopped charging. I've put 2 new alternators in it and its still only reading 12.5v at the battery when on and 12.5v when off. I've followed all the walk throughs multiple times and its still not getting me any where. The car is a 1970 240z, whats tripping me up is my voltage reg. only has 5 wires going to it, not 6. Is that whats causing my issue?

Using that picture my #5 connector is seeing like 16v and #4 is seeing right at ~11.9.

My #1 wire on that diagram is MIA, the harness didnt even have a spade for it. Is that whats tripping me up?

[EScanlon]

That White wire with the spiral Blue Stripe, where is that connected FROM and TO?

Since it's bundled with the wires going to the V/R, then presumably (and apparently from the black shrink? tape with yellow lettering) it's connected to the other side of the connector bundle, which may be where your missing 6th wire is.

But, checking with my wiring diagram, I do NOT find that White/Blue #4 wire in the schematic. Nor the White/Red #1 at the V/R (just to the Alternator).

This may be one of the early 70 wiring idiosyncracies not seen in later models, but I can't say for sure.

All that being said, I would check if a new / different Regulator would be the ticket.

E

[Pleadingbark]

Thats just a picture I found online that I was going by. The cars a 10/70 build date. Ive got a zx internally regulated alt on it now. At the + post on the alternator its putting out ~16v. Could I just connect with a 8ga wire that to the starters + terminal which then connects to the 12v + from the battery?

[Zed Head]

I don't know the details of 1970 240Z wiring, but if you're reading 16 volts off of the alternator then it is working. I'm with EScanlon's last comment, the problem is with your regulator. You should change the regulator, not the alternator. If the wiring is stock, and it worked before, just leave the wiring alone and replace the regulator.

The pictures in your first post are borrowed from a different post, right? That's not your wiring?

Edit -totally missed all of the relevant facts in Post #3. Never mind.

Edited November 20, 2011 by Zed Head

[EScanlon]

Thats just a picture I found online that I was going by. The cars a 10/70 build date. Ive got a zx internally regulated alt on it now. At the + post on the alternator its putting out ~16v. Could I just connect with a 8ga wire that to the starters + terminal which then connects to the 12v + from the battery?

There's the problem....

REMOVE your OEM Voltage Regulator and replace it with the Voltage Regulator Adapter that Arne used to make, and is now available from MSA. Without this you've not completed the circuitry that you changed to with the internally reg. alt.

FWIW

E

[Pleadingbark]

There's the problem....

REMOVE your OEM Voltage Regulator and replace it with the Voltage Regulator Adapter that Arne used to make, and is now available from MSA. Without this you've not completed the circuitry that you changed to with the internally reg. alt.

FWIW

E

I did, it made no difference. Just ran an extra 4ga wire from the alt to the starter post and its sitting 14.4v on the battery. The battery gauge in the car reads below the middle, but I guess I just dont worry about it now.

[Zed Head]

What did you do with the original wire from that alternator post? It's still hot, the other end is just not connected to what it should be. If you've replaced it with the new wire, you might as well disconnect it before it shorts out.

[Zs-ondabrain]

So lets get this figured out........

Did you buy the adaptor plug (280ZX alternator adaptor plug) from Motorsport, and install it?

If no, then there's your problem.

If yes, are there any broken wires on the engine harness side of the Voltage regulator plug?

Have you ran an 8 guage wire from the back of the alternator to the starter power bolt?

When you do this, the ammeter gauge will barely move anymore do to the 8 gauge wire basically bypassing the meter.

So if it helps, List step by step what yo've done and the result of that action.

Dave

[Pleadingbark]

What did you do with the original wire from that alternator post? It's still hot, the other end is just not connected to what it should be. If you've replaced it with the new wire, you might as well disconnect it before it shorts out.

I left the original wire on the alternator post also. It was a thick white and red or black striped wire.

Zs-ondabrainSo lets get this figured out........

Did you buy the adaptor plug (280ZX alternator adaptor plug) from Motorsport, and install it? No made my own. Oddly enough if I dont plug anything in there it will start and turn off fine, but if I just put jumpers in it wont turn off. The little adapter plug I made jumps the connections and allows the car to turn off.

If no, then there's your problem.

If yes, are there any broken wires on the engine harness side of the Voltage regulator plug? Yes Im missing a wire from the plug. I unloomed the harness in the engine bay up to the firewall and I cant find where there would have ever been a trace of the wire.

Have you ran an 8 guage wire from the back of the alternator to the starter power bolt? Yes thats what I ultimately ended up doing.

When you do this, the ammeter gauge will barely move anymore do to the 8 gauge wire basically bypassing the meter. Oh, that explains everything. Is there a way to run that ammeter wire to a different positive source, or should I just really worry about it?

So if it helps, List step by step what yo've done and the result of that action.

Dave

[SteveJ]

No made my own. Oddly enough if I dont plug anything in there it will start and turn off fine, but if I just put jumpers in it wont turn off.

Go to this link and read the Special Note section.

[Zs-ondabrain]

Ignore the black wire on the plug, it's just a ground for the original Voltage regulator.

The black/white and white/black should have a Diode between them w/ the stripe of the diode on the White/black wire side.

The Yellow and white wires should be connected together, with no diode.

You said there's a wire missing?? There are only 5 wires in the 6-pin connector. Listed in the above paragraph.

You need to go to radio Shack or ??? and buy a 1 amp diode and install it between the B/W and W/B wires so they are connected but the diode will stop the electron flow from going the wrong way (That's why the car still runs after key is off.

The ZX adaptor plug would have done all this for you in a simple "Plug-N-Play connection"

That's your problem, in a nut-shell

Dave

*P.S*

Ignore the colored wires on the Pictures you posted. Those are Voltage Regulator wires that don't match up (in color) to the actual Datsun colors. Just follow my directions above and you'll be fine.

Edited November 21, 2011 by Zs-ondabrain