I have put new connectors on the voltage regulator wiring.  I wired the connectors exactly as they were before going to paint.  One of my questions is why are there only 5 wires coming from the wiring harness, but 6 coming from the voltage regulator.  The white wire with red stripe (IMG_7889.jpeg) from the voltage regulator does not connect to a wire from the harness.  Also there is a single black wire with white stripe (IMG_7890.jpeg) coming from the harness that does not appear to connect to anything.  Anyone know what the wires purpose is?

Greg

You don't have a stock voltage regulator. The wiring diagram shows 5 wires.

Sense means it is reading battery voltage. Field is the wire that it uses to excite the field of the alternator. Neutral is the neutral of the alternator. The L terminal isn't used, but it would be for the Lamp signal. If it was used, it would connect to a bulb in the dash, and the other side would have a switched source. If the alternator wasn't charging, the bulb would light up. It's a shame they didn't use it.

The BW wire with the bullet connector is for a condensor that isn't shown in the wiring diagram. It resides around the VR.

Thx for the help Steve.  

@SteveJ , I’ve got a ‘73 240z, and I’m chasing an electrical issue. Here’s what I’ve got:

• I changed the voltage regulator some time ago. It’s delivering 17 V when the car is running. I’ve cooked the battery and the radio has stopped working. I haven’t checked the radio fuse yet.

• The PO made changes to the wiring harness. None of the wire colors are OEM and the junctions at the cabin firewall have been deleted.

• The sense wire has a connector just inside the cabin. With the car off and the wire disconnected on both ends (in the cabin and at the VR) I get 7V, so I’ve got a short to hot and need to replace that wire.

• With the sense wire connected, I get zero V, so I’ve got some sort of short or break in the cabin as well.

  I see your diagram above says radio next to the sense wire. Is that wire also the unswitched power to the radio? Two shorts seems like pretty big coincidence. Any other suggestions?

Conventional wisdom says that the sense wire should come from as close to the battery as possible.

The image I posted has "radio" near the wiring only because Nissan was cramming the whole wiring diagram onto an 8.5x11 page. When you look at the bigger picture, you can see that the white wire branches off after the fusible link at the starter. In other words, they have it coming from close to the battery.

Does the sense wire normally go into the cabin? Since the colors are wrong, I found the only wire with voltage while the car was off. From the full diagram, I’d expect that wire to be under the hood.

As I just explained

21 minutes ago, SteveJ said:

Conventional wisdom says that the sense wire should come from as close to the battery as possible.

The image I posted has "radio" near the wiring only because Nissan was cramming the whole wiring diagram onto an 8.5x11 page. When you look at the bigger picture, you can see that the white wire (sensing) branches off after the fusible link at the starter. In other words, they have it coming from close to the battery.

6 hours ago, 73avocado said:

1. The sense wire has a connector just inside the cabin. With the car off and the wire disconnected on both ends (in the cabin and at the VR) I get 7V, so I’ve got a short to hot and need to replace that wire.

2. With the sense wire connected, I get zero V, so I’ve got some sort of short or break in the cabin as well.

This doesn't make any sense. (😄)

When I first started messing with my VR and alternator I tried to follow wire color instructions from the old internet and I just ended up with problems. So I just figured out what each wire's function was and made my own diagram.

Focus on the function and you'll see that you don't need to worry about where a wire is supposed to be. There's only four circuits and two are obvious.

Also, your logic in the posts above does not seem right. You might review what's supposed to happen in the alternator before moving forward. Unfortunately there is a ton out there on the internet about sense wires and exciter wires and lamp wires, etc. , and one, two, three, and four wire setups. It's kind of a mess.

You might have to wade through some of it to get a good feel for what you want to do. But once you get a feel for the S(ense) circuit and L(amp) circuit it kind of falls in to place.

16 hours ago, 73avocado said:

I changed the voltage regulator some time ago. It’s delivering 17 V when the car is running.

16 hours ago, 73avocado said:

The sense wire has a connector just inside the cabin. With the car off and the wire disconnected on both ends (in the cabin and at the VR) I get 7V, so I’ve got a short to hot and need to replace that wire.

16 hours ago, 73avocado said:

With the sense wire connected, I get zero V

I feel compelled to post again. I misunderstood that you were still using a "stock" regulator. Apparently. My comments above were directed toward the wiring for an internally regulated alternator, with S, L, B, and G.

But, it's not clear that you know what you have. You said that you changed the regulator but it's not clear that your regulator is actually wired correctly. The PO might have converted to internal. Why did you change the regulator and why did you run so long with overvoltage (no regulation)?

You said that you get 7 volts but didn't say where you were measuring this. Or why you think that you have a "short to hot". A short to "hot" should give battery voltage. About 12.6.

Anyway, I know that you asked SteveJ specifically and he answered specifically, but, generally, what you've described doesn't make sense.

If you use SteveJ's diagram in Post #2 and the drawing from the FSM you should be able to measure Sense right at the regulator plug itself, see below.

The pin to the White wire (A) should read battery voltage. Just unplug it from the VR and measure. If you don't have battery voltage then somebody has messed something up.

Sorry for the confusion. Got bored and didn't think it through. Might help you also to post a picture of your alternator.

No worries, thanks for the follow up. Looks like I’ve got a Franken-charger. I believe it’s still running off the external regulator, but it’s got a later-model Mitsubishi alternator. It’s also got a second connector between the VR and the alternator. The alternator has 6 wires including the main output and ground, but it’s only wired to use 4. It’s got B, A,N,F, E and the large ground. It’s only using B, N, F, and the large ground.

Out of the VR, there are two wires tapped to one connection point. I think that’s my lamp since one wire goes into the cabin.

I also found a wire nearly broke off in one connector and the same wire on the other side of the plug was scorched. Both sockets were full of green corrosion. I’m 90% sure it’s the sense wire out of the VR. At this point I’m going to start with new plugs and wires all around, then see where I end up.

1 hour ago, 73avocado said:

later-model Mitsubishi alternator. It’s also got a second connector between the VR and the alternator. The alternator has 6 wires including the main output and ground, but it’s only wired to use 4. It’s got B, A,N,F, E and the large ground. It’s only using B, N, F, and the large ground.

Might be a standard replacement. Here's what your 73 came with. Borrowed the picture from ZCD.

Okay then, looks messy. Good luck.