First off I searched and couldn't find this exact situation.

I did the swap from the old 40A/ext. reg. and it was very easy but now I have no battery charge.

Of course I never bothered checking the charge state with the old alt/reg installed.

I used the diode plug for the old regulator wiring that MSA sells and followed the instructions for the install of the new alternator.

The alternator is a rebuilt 1982 ZX unit from Advance Auto.

I also replaced the frayed fusable link for the wire from the harness to the starter/battery so that's good.

All tests were while the car is running.

11.8v across the battery.

11.8v at the fusbale link to harness connection to ground.

17.2v from B terminal on the alternator to ground.

After running the car for more than 20 minutes and turning it off about 2 times, it won't start without a charge first.

Do you think I have a bad wire somewhere between terminal B and the fusable link harness?

 

 

Edited February 29, 20169 yr by SurferD

2 hours ago, SurferD said:

no battery charge.

11.8v across the battery.

17.2v from B terminal on the alternator to ground.

After running the car for more than 20 minutes and turning it off about 2 times, it won't start without a charge first.

Do you think I have a bad wire somewhere between terminal B and the fusable link harness?

Sounds like 2 wires aren't connected.  The one from B to the battery positive terminal, and the S wire at the alternator.  But they might both run through the same fusible link.  Find the fusible link that's in the wire from the B terminal to the battery post.  Actually it would be the white wire that connects to the starter lug, that's show Nissan got it there. If you accidentally touched the end of the white wire at the alternator to ground with the battery connected you'd blow that link.

The short diagnostic method would be to measure resistance from the battery + post to the alternator B terminal.  You'll probably find it's open circuit, then go from there.

Thanks I'll try that.

On February 29, 2016 at 2:04 PM, Zed Head said:

Sounds like 2 wires aren't connected.  The one from B to the battery positive terminal, and the S wire at the alternator.  But they might both run through the same fusible link.  Find the fusible link that's in the wire from the B terminal to the battery post.  Actually it would be the white wire that connects to the starter lug, that's show Nissan got it there. If you accidentally touched the end of the white wire at the alternator to ground with the battery connected you'd blow that link.

The short diagnostic method would be to measure resistance from the battery + post to the alternator B terminal.  You'll probably find it's open circuit, then go from there.

I took apart the B lug harness and found that the white/red stripe wire had a bad solder repair that looked like it was in the factory wrapping. I cut it and resoldered a better connection. Unfortunately I have an open still. The plain white wire that goes to the starter fusable link is also open. Where do both the white and striped wire go inside the dash? I assume they connect somewhere to provide alternator power to the battery.

Should I make a jumper from B to the fusable link and see what happens?

I just had the dash out too to track down mystery smoke.

Edited March 8, 20169 yr by SurferD

Open to where?  You mean no connection to the battery?  Or the new alternator?

Your car has/had an ammeter.  That might be where all of your problems are centered, including the smoke.  I commented in general terms about why things weren't working, but someone with an ammeter probably knows the details of your situation.  We could could easily get the alternator to work, using two jumper wires, but not the ammeter.  Plus, the short that caused the smoke might still be there.

You didn't mention the smoke before.  Was it before or after the alternator swap?  Might want to write up a short history of why you did the swap, when the smoke appeared, and any odd things that might have caused problems.

3 hours ago, Zed Head said:

Open to where?  You mean no connection to the battery?  Or the new alternator?

Your car has/had an ammeter.  That might be where all of your problems are centered, including the smoke.  I commented in general terms about why things weren't working, but someone with an ammeter probably knows the details of your situation.  We could could easily get the alternator to work, using two jumper wires, but not the ammeter.  Plus, the short that caused the smoke might still be there.

You didn't mention the smoke before.  Was it before or after the alternator swap?  Might want to write up a short history of why you did the swap, when the smoke appeared, and any odd things that might have caused problems.

Open between B red stripe white wire and battery +

I upgraded the ignition to a Pertronix and didn't want an issue with the old regulator.

After I put in the new alt I had a very faint electrical burning smell and smoke behing the instruments. I removed the dash and found nothing. It never came back so I thought I was good. then the charging issue started.

According to the Nissan shop manual I have the alternator lead goes to the ammeter then to the battery.

If something happened there that would explain it. My ammeter does move when I turn the lights on though.

 

Edited March 8, 20169 yr by SurferD

I think that there's a fusible link on the charge wire.  It may have blown when the smoking started and saved you from more damage.

Seems like you have something wired wrong and you should probably figure it out before replacing the link, if you can find it.  It should be exposed, not buried in harness wrap, so that it can be replaced.

I'd start from scratch and examine all of your wiring.

I'm doing that. I bypassed the ammeter by connecting white and white/red stripe wires so that's out of the loop now.

Do you think that the soldered wire was factory?

Edited March 8, 20169 yr by SurferD

I don't think that factory used soldering to splice or tap wires.  They used crimped connectors.  

If you start a new thread with "1970 ammeter shunt charging problem" you might catch the eye of one of the 240Z electrical gurus.  Steve J and CO know a lot along with several others.  Charging problems are usually boring, but yours has more meat to it.  I know the internally regulated alternators basics, but not much ammeter stuff.

I've been keeping an eye on the progress here for places where I might be able to add value, but I just don't know where to start.

Non stock connections buried down inside the harnesses? Smoke coming from the harness in the interior? Then the smoke stops and no problem was found? Questionable fusible links? I just don't know where to put a stake in the ground to get troubleshooting started.

The only documentation I have is from the manuals, and the early manuals can be a little light on info. I'm really sorry, but If your car doesn't match the manuals, I just don't know how to communicate troubleshooting info.

Maybe some pics would help?

I believe that sometimes people think the crimp is non-stock and try to fix it with solder.  Or just don't like crimps and solder as an improvement.  Who knows.  I remember finding my first crimped connection in my 280Z harness and wondering what the heck it was doing there.  Before I knew a little more.  It just seemed so exposed.  

The wiring diagram from the 1970 Owners Manual shows an "alternator fusible link".  I would find that, it looks like it's down by the alternator.  If it's "fused" or "defused" though you'll still need to find the short.  It's probably on the alternator side, it would blow from battery voltage.  Leading to the possibility that your new/old internally regulated alternator is shorted inside.  OR you chose the wrong post on the alternator.  Makes sure that the post you connected to has a B stamped in to the housing, AND check its continuity to the case and ground.  The B post should be open circuit, non-continuity, to the alternator case.  Maybe you just got a bad alternator and the fusible link did its job.

Edited March 9, 20169 yr by Zed Head
Forgot the picture

Sounds like it's time to pull engine bay harness and cut it open.

This is what I found in a 240Z harness last year and everything was working!