My Monte isn't charging, internal regulated alternator wiring question...

[o_rod]

I just picked up my Monte a week ago and it has had a charging issue since I've had it. My battery, while it's running reads 12.8 volts, doesn't matter if I raise RPM's. Also, the "gen" light stays on while the car is off and no key in the ignition. When I start the car it turns off.

 

Now I've done some research and it looks like I have an internally regulated alternator as the 2 wire plug is like this [--] instead of like this [iI]. I was under the impression that if it is internally regulated, I should bypass the external regulator? It still looks like it is connected, it also looks like it's been recently replaced.

 

It also seems my headlights aren't working! 

 

 I took some pictures of how everything is set up, maybe someone can identify this alt for me and if everything looks alright?

 

 

[Rock]

If your alternator has internal regulation you have to bypass the voltage regulator.

https://www.google.com.mx/search?q=bypass+voltage+regulator+chevy&client=safari&channel=iphone_bm&prmd=visn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiasMHkiMrPAhUF6YMKHeIABPoQ_AUICCgC&biw=1024&bih=672#imgrc=xjfEEgFIb35tEM%3A

[cny first gen 71]

That sure looks like an external regulator to me in the third picture. may want to check some of that wireing, the way its spliced in there.

[Mike Brichta]

That looks like an externally regulated alternator (like the original).  The problem is probably the voltage regulator.

 

However, I would STRONGLY suggest switching over to an newer internally regulated alternator.  I converted all of my cars that way.  I have instructions on how I did it if that would help.

 

Mike

[o_rod]

I planned on going to an internally regulated one anyways but I was under the impression that if the 2 plug harness on the alt had the pins shaped the way mine are its internally regulated? I think the previous owner might have changed the Alt and didn't know the difference... I thought the original alts for these cars had the plug shaped like this [||] where's mine is like this [--]

 

With it wired the way it is, if I unplug the 2 wire harness at the alt the gen light goes out when the car is off. If the car is running and the harness is plugged in, the alt makes a louder whirring noise that goes away when it's unplugged too.

[stangeba]

My OEM 71 Alt.

[o_rod]

Thanks for that, definitely not the same as mine. I believe mine is indeed an internally regulated alt still running through the external regulator. I'll rewire it once I get the chance and report back.

[stangeba]

Do you have gauges in the car?

Factory?

Aftermarket?

You should be able to take the alt to a auto parts store and they will check it for free.

 

Bryan, btw, great pictures!

Bruce

[John S]

At the external voltage regulator the white wire is cut and not used. The blue and brown wires are spliced together. The red wire at the two wire alternator connection is the sensing wire. You can run that wire to and splice that to the red wire from the 4 wire connecter at the external regulator. That is the way I hooked mine up and works fine. Some diagrams will show jumping the red wire at the alt to the red power wire that connects to the back of the alt. Not a good choice since as I said the red wire is the sensing wire and with that short of a wire will not properly sense voltage drop and charge correctly. Very simple.

John S

[Leghome]

I have seen something that has intrigued for me quite a while. Alternator, internal regulated that looks like Bryan's, reversed the two wires coming out of the alternator from factory setting, unplugging the regulator and jumping the outside wires and jumping the inside wires so everything works like it did from the factory sans the external regulator. I cannot for the life of me remember where I saw that at.

[o_rod]

Like this Larry?

 

 

That's what I'm in the process of doing right now... But this wiring is an absolute nightmare! 

 

I found the #2 wire from the ALT going to the starter!! Then I found the #1 wire from the alt going to the #4 on the external regulator! What is going on!!! 

 

I'm assuming the starter just needs a ground, a sensing wire from the ignition and the positive lead from the battery? 

 

[Leghome]

The regulator rewire looks like that. I cannot remember the alternator wires, I just remember reading  that they had to be reversed for the factory setup and changed to the correct plug for the alternator. 

[o_rod]

After the rewire my alt is still showing the gen light on with the car off. Looks like it's time for a new alt...

[Leghome]

You can take that Alt into about any parts house and the can test it for you. I know our NAPA has a real good test station.

[o_rod]

Took it to a local alt rebuild guy and everything was toast in it except the stator. Turns out it's a 15si which is pretty strong, he rebuilt it to new condition and the car is now charging like a dream. 14.5 at idle!

 

Apparently if the gen light is on while the car is off it's the diode trio that's trashed FYI.

[stangeba]

Great news!

IMO, much better that swapping it for a "rebuilt" alt. from a paerts store.

Bruce