o_rod Posted October 8, 2016 Share Posted October 8, 2016 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? Quote Link to comment Share on other sites More sharing options...
Rock Posted October 8, 2016 Share Posted October 8, 2016 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 Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted October 8, 2016 Share Posted October 8, 2016 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. Quote Link to comment Share on other sites More sharing options...
Mike Brichta Posted October 8, 2016 Share Posted October 8, 2016 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 Quote Link to comment Share on other sites More sharing options...
o_rod Posted October 8, 2016 Author Share Posted October 8, 2016 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. Quote Link to comment Share on other sites More sharing options...
stangeba Posted October 8, 2016 Share Posted October 8, 2016 My OEM 71 Alt. Quote Link to comment Share on other sites More sharing options...
o_rod Posted October 8, 2016 Author Share Posted October 8, 2016 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. Quote Link to comment Share on other sites More sharing options...
stangeba Posted October 8, 2016 Share Posted October 8, 2016 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 Quote Link to comment Share on other sites More sharing options...
John S Posted October 8, 2016 Share Posted October 8, 2016 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 Quote Link to comment Share on other sites More sharing options...
Leghome Posted October 8, 2016 Share Posted October 8, 2016 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. Quote Link to comment Share on other sites More sharing options...
o_rod Posted October 9, 2016 Author Share Posted October 9, 2016 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? Quote Link to comment Share on other sites More sharing options...
Leghome Posted October 10, 2016 Share Posted October 10, 2016 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. Quote Link to comment Share on other sites More sharing options...
o_rod Posted October 10, 2016 Author Share Posted October 10, 2016 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... Quote Link to comment Share on other sites More sharing options...
Leghome Posted October 10, 2016 Share Posted October 10, 2016 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. Quote Link to comment Share on other sites More sharing options...
o_rod Posted October 17, 2016 Author Share Posted October 17, 2016 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. Quote Link to comment Share on other sites More sharing options...
stangeba Posted October 17, 2016 Share Posted October 17, 2016 Great news! IMO, much better that swapping it for a "rebuilt" alt. from a paerts store. Bruce Quote Link to comment Share on other sites More sharing options...
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