Alternator problems/ charging circuit diagram

[bluescout]

I just tested my alternator "trigger" wire and it seems to not be working. My alternator doesn't come on until I rev it, which is in line with that as well. Anyone have a diagram that will show me where it goes? In normal cars, power goes to an alternator light, then to that term on the alternator to turn it on. I don't think we have alternator lights.

 

[damnesia]

It would be helpful to know what scout model you're asking about

 

[BuffScout]

I just tested my alternator "trigger" wire and it seems to not be working. My alternator doesn't come on until I rev it, which is in line with that as well. Anyone have a diagram that will show me where it goes? In normal cars, power goes to an alternator light, then to that term on the alternator to turn it on. I don't think we have alternator lights.

Depends on what you have. 80 or 800, engine?

 

[Patrick Morris]

It would be helpful to know what scout model you're asking about

The sig just mentions a 1979 Scout II. No idea what "full of fiberglass and diesel fuel" means. Nissan diesel engine then?

 

[jeff campbell]

May be a glass scout as well ?

 

[Patrick Morris]

May be a glass scout as well ?

True. But I was wondering more about the engine, and from there, the alternator type. Did IH stick 10SIs on the Diesels? Or did they have Japanese alternators?

I think it'll affect which wiring diagram the OP wants to see.

 

[jeff campbell]

True. But I was wondering more about the engine, and from there, the alternator type. Did IH stick 10SIs on the Diesels? Or did they have Japanese alternators?

I think it'll affect which wiring diagram the OP wants to see.

They had the nippendenso alternators.

 

[Patrick Morris]

I was thinking Nippon-Denso if Japanese. But I was doing a little reading and one guy who had a diesel said his alt was made by Hitachi. And point of interest, those had external voltage regulators. He posted a pic of his VR. Don't know if it'll help the OP or not. VR may not have anything to do with the "trigger" wire anyway.

 

[BuffScout]

I was thinking Nippon-Denso if Japanese. But I was doing a little reading and one guy who had a diesel said his alt was made by Hitachi. And point of interest, those had external voltage regulators. He posted a pic of his VR. Don't know if it'll help the OP or not. VR may not have anything to do with the "trigger" wire anyway.

View attachment 239234

It may be the source. At one point I had a similiar issue. Discovered the plug on my vr wasn't securely on all 4 blades....worn pretty much. Replaced with new & problem solved

 

[Mark Pietz]

I had that same problem on a 1975 Scout (never solved it; just lived with it) and it also appeared on my 1980 Scout. Problem finally went away when I replaced the 14 gauge fusible link that went from the solenoid "battery" lug and transitions into a 10 gauge wire that goes to the firewall bulkhead connector. It would still conduct electrically (ohm meter showed continuity) but it was bad. I suspect it is a more common problem than one would believe.

 

[jordandoc]

If you're talking about the "excitor" wire, the brown one with the white stripe, if I remember correctly it goes to a terminal on the ignition switch. With the key "on", the terminal is hot sending a signal to the alternator. It is a 24 gauge resistor wire and runs from the alternator to a dash connector...then connects to a ? 2 or 3 wire connector that steps it up to an 18 gauge wire that plugs into the ignition switch. It may be a little different on a newer Scout or one with an auto tranny but I was working with a '74 4-speed with flickering dash and headlights. It cured the problem!

 

[bluescout]

I'm totally sorry, I've been busy. It's my new '79 345 Traveler. I guess I should update my sig!!

I tracked down some info searching here and ended up finding a portion of the ignition switch unplugged!!! The only 2 wires in that plug were the alt wire and a wire that gets grounded on START. Previously, it wouldn't charge until I revved it, and it was not consistent, sometimes going full charge momentarily. Fixed everything up now I think.

 

[Patrick Morris]

Good deal. Glad you fixed it.

I was talking about alternators in a different thread, different section of the forum. We found out that my wife's Subaru CrossTrek won't charge the battery unless the headlights are ON. And that's a "feature", not a bug. Kind of common these days among auto manufacturers to have a 'smart' charging system; helps apparently with emissions/fuel economy and maybe belt life? At the expense of killing batteries more often. I'm rigging her car for a easy hookup of the battery tender.

 

[bluescout]

Good deal. Glad you fixed it.

I was talking about alternators in a different thread, different section of the forum. We found out that my wife's Subaru CrossTrek won't charge the battery unless the headlights are ON. And that's a "feature", not a bug. Kind of common these days among auto manufacturers to have a 'smart' charging system; helps apparently with emissions/fuel economy and maybe belt life? At the expense of killing batteries more often. I'm rigging her car for a easy hookup of the battery tender.

Thanks!! It was a surprise to find it unplugged

Newer cars no longer have a regulator in the alternator, the computer controls the field and demands voltage for whatever the conditions are. Maybe so as not to burn up batteries or use too much energy unless necessary.

 

[Patrick Morris]

Right. But there's a lot of angry/frustrated people out there though, having had to replace the battery in their 1-year old car. Then having to buy another battery after that one dies a year or two later. I'm talking Subaru and Honda owners anyway. I've been doing some reading. The charging systems have become "smart" to a fault. They don't charge the batteries often enough nor up to anywhere near full capacity, it seems. So that, compounded with if there's any kind of drain. like a light left on, or even if the fob that controls vehicle access is too nearby, it takes the battery down to an unusable state quickly.