# GM Alternator



## Ed Williams (Jun 13, 2019)

The GM alteRnator on the NAA will not charge after the recent wiring shorts caused by rodents. I cannot get a comnection on the exciter wiring from switch to alternator. Is this wire supposed to show continuity to ground with switch off. I went ahead and ordered some rebuild parts instead of forking over the big bucks for a new alternator. Kit includes new brushes and brush holder, diode trio and voltage regulator. Is there a way to test these individual components, or just replace the whole lot? The rectifier was not included and turns out to be a big buck item that drives the rebuild to almost the price of a new alternator. Any way to test the rectifier? No electrician and all this is new to me. Dismantle of the old alternator was simple and straightforward, but I cannot seem to locate any test procedures for the. Individual components.


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## Hacke (Feb 22, 2011)

What GM alternator do you have?:
https://alternatorparts.com/how-to-identify-your-gm-alternator.html

Some useful information:
https://alternatorparts.com/sitemap.html


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## Ed Williams (Jun 13, 2019)

acdelco s15


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## Hacke (Feb 22, 2011)

Look at this:
https://alternatorparts.com/10si-15si-type-116-136-repair-manual-contents.html

and this:
www.gmcmhphotos.com/photos/data/6522/Delco_Alternator.pdf


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## Groo (Jan 17, 2020)

Maybe just toss in a 1 wire alternator?


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## Ed Williams (Jun 13, 2019)

Don't want to spend another $130 for a new alternator


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## Ed Williams (Jun 13, 2019)

Hacke said:


> What GM alternator do you have?:
> https://alternatorparts.com/how-to-identify-your-gm-alternator.html
> 
> Some useful information:
> https://alternatorparts.com/sitemap.html


Thanks for the great info. Think it will help tremendously.


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## willy81 (Jan 30, 2020)

Hacke said:


> What GM alternator do you have?:
> https://alternatorparts.com/how-to-identify-your-gm-alternator.html
> 
> Some useful information:
> https://alternatorparts.com/sitemap.html


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## ksg32198 (Feb 5, 2018)

I added the GM SI alternator to my Ferguson TO-20. Its very simple to wire up and a couple of ways you can do it. Most SI alternators have 3 connectors which are the battery post on the back and 2 terminal connectors from the regulator. Terminal 1 connects to your charging lamp indicator and to the ignition switch or it can go directly to the ignition switch. Terminal 2 is how the regulator "excites" by what the battery voltage is. You can either run a line directly to your battery post for it to get the voltage or like most people do, they connect terminal 2 directly to the post on the back of the alternator because it already goes to the battery to charge it so it has the voltage right there. See the example below. As far as testing the alternator, you can use your ohm meter to test the stator, rotor, rectifier bridge and diode trio. Remember the Diode Trio is a diode(One Way Gate) so when testing it, you should get a reading one way, but no reading when you reverse the leads. That link above from Hacke is a good tutorial on testing the components.


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## Hacke (Feb 22, 2011)

Terminal 2 is the sensing terminal. If you just jump that to the alternator's B+ (like in your picture), you do not get the benefit of remote voltage-sensing. See this:
http://www.madelectrical.com/electricaltech/remotevoltagesensing.shtml


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## Ed Williams (Jun 13, 2019)

Hacke said:


> Terminal 2 is the sensing terminal. If you just jump that to the alternator's B+ (like in your picture), you do not get the benefit of remote voltage-sensing. See this:
> http://www.madelectrical.com/electricaltech/remotevoltagesensing.shtml


That's why it is called a 3 wire alternator. The NAA is wired with a remote sensing wire at a home made junction block under the hood mounted at the original 6v voltage regulator location. I also have a 194 socket and bulb on the exciter wire to indicate alternator function. Quite useful as the bulb does actually go on if the alternator is not charging properly. That was the first indication that I had a charging problem after the wiring fiasco with the rodents. It's also interesting to note that the 3 wire alternator is $30 cheaper than a 1 wire at the local parts store, and they really push the 1 wire. I got into an argument with the snot nosed clerk when I was doing the original 12v conversion. He refused to sell me the 3 wire. I had to get the manager over to complete the purchase of the 3 wire. Suspect he was operating on commission. I hate it when I know what I want, and some kid tells me I don't know what I am doing. I have been friends with the manager for many years so things are okay with us, but the smart mouthed kid no longer works there.


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## Hacke (Feb 22, 2011)

Ed Williams said:


> That's why it is called a 3 wire alternator. The NAA is wired with a remote sensing wire at a home made junction block under the hood mounted at the original 6v voltage regulator location. I also have a 194 socket and bulb on the exciter wire to indicate alternator function. Quite useful as the bulb does actually go on if the alternator is not charging properly. That was the first indication that I had a charging problem after the wiring fiasco with the rodents. It's also interesting to note that the 3 wire alternator is $30 cheaper than a 1 wire at the local parts store, and they really push the 1 wire. I got into an argument with the snot nosed clerk when I was doing the original 12v conversion. He refused to sell me the 3 wire. I had to get the manager over to complete the purchase of the 3 wire. Suspect he was operating on commission. I hate it when I know what I want, and some kid tells me I don't know what I am doing. I have been friends with the manager for many years so things are okay with us, but the smart mouthed kid no longer works there.


I guess the clerk was afraid of being asked to explain the wiring after selling a 3-wire alternator?

It seems to be a lot of people doing the jumper connection. Have they never asked themself why? If it was supposed to be connected like that, the manufacturer would have made the connection inside the unit and omitted the terminal.


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## Ed Williams (Jun 13, 2019)

Hacke said:


> I guess the clerk was afraid of being asked to explain the wiring after selling a 3-wire alternator?
> 
> It seems to be a lot of people doing the jumper connection. Have they never asked themself why? If it was supposed to be connected like that, the manufacturer would have made the connection inside the unit and omitted the terminal.


I do not like the shortcut. The alternator function and control were designed by people much smarter than I am, so I followed the instructions in the alternator box. Plus Yesterday's Tractor had wiring diagrams showing both installation methods. The diagram showing the voltage control wire going to a remote terminal block near the battery was labeled "GM Recommended Installation". The alternate jumper method was labeled "älternate wiring method". The choice to me was obvious. It was only 5' of wire difference.

On another note. I spent a long hard day replacing all the wiring toasted by critters chewing it to bare metal. Well, I took all that back off. It only took 3 hours to strip it off. I came up with a better idea. While rumaging in the old barn for roofing metal that had blown off I found an old 25 foot length of 1/2" hose that had seen better days. It was in a manger stall that never saw sunlight, so it had been protected. It had to be from the previous owner, and I have had it for 32 yrs. Therefore, it had to be manufactured prior to the use of soybean extract in its manufacture. It was really stiff and acted like a spring when I tried to uncoil it. I read somewhere about a conditioning treatment to protect old and stiff hoses. Here we go again. It was 35 deg and raining today. So I built a very small fire under the new canopy. The fire kept my bare hands warm and softened the hose where it was pliable. I worked the hose in the hot air above the fire until it was warm to the touch and applied liberal amounts of WD-40 with a saturated rag. In 3 hours I had a clean and limber hose that looked brand new. The old hose sucked in the WD-40 like mad. I cut the hose to lengths for the wire runs on the tractor and started threading the wire thru the hose. Then made some wire hangers by taking old 1/2" copper pipe in short lengths and hammered it flat, then bent it to shape in the vise over a piece of 3/4 bar stock. Perfect hangers for the 1/2 hose. Hose was stiff enough to maintain 3 ft runs and flexible enough to route on the tractor. the WD-40 should ward off critters, but then got a little silly. After the wire runs were made inside the fitted hoses, I sealed one end with black tape, suspended them vertically from the garage door runners and filled them with finely ground rat poison from a coffee grinder, then sealed the top end with black tape. I left 12"of wire sticking out each end for final connection. My version of the homemade rat trap. Come on critters. I have a surprise for you. Old people will do some really strange things when there is too much idle time. Anyway, I feel better with the wiring now enclosed in a protective cover.


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## Allen Mader (Nov 27, 2019)

Hope you cleaned the coffee grinder good after grinding up rat poison! If we ever meet for coffee, I will buy.


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## Ed Williams (Jun 13, 2019)

Allen Mader said:


> Hope you cleaned the coffee grinder good after grinding up rat poison! If we ever meet for coffee, I will buy.


I don't drink coffee. I like the smell but not the taste. I am a tea drinker instead. I actually have 3 coffee grinders that I use specifically to pregrind the 3 components of black powder before final mixing and final 12 hour grind in the home made ball mill. Ball milling is absolutely essential to make a quality "green powder" before final processing to black powder. It doesn't actually turn black until the water addition step of the processing. The final ingredient, dextrose, has the consistancy of talcum powder and does not require grinding. It is only added to the ball mill mix for 45 minutes, or it will degrade. Yes, I make my own black powder and screen size it to 2f or 3f. I use Goex as a standard for comparison. Goex quality control is a 1/4 strip 4 inches long to burn in 1 second. Mine is slightly faster than that and works great in long arms, pistols, and model rocket motors for the grandkids. Have to cut it with powdered sugar for the rocket motors to slow it down, or BANG. The last batch I made was 37 pounds. Works great on stumps too. Great thing about black powder is water does not destroy it like the synthetics. Water is essential in the last steps prior to sizing to form the hard flakes with the dextrose. You can even resize a batch by adding water, run through a different sizing screen, and let air dry.


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## Ed Williams (Jun 13, 2019)

Update. I thought I knew a lot about tractor electrical systems, conversions and rewiring. WRONG. Since the total rewire of the NAA after the critter incident, I have had a terrible time Keeping it running. Hard starting, occasional misfire to varying cylinders, etc, etc. Wound up doing another complete rewire with new wire. Thought some of the old wire might be corroded inside causing the problem. After 2 weeks of steady work on it, the same results. Compression good, fuel good, good spark on all cylinders, but won't run without misfire and no power. I sat for 2 solid hours with voltmeter hooked to positive side of the coil. Volt readings ran from 4v to 13v, very intermittant. WHAT the Hell. The idiot light on the exciter line to the alternator was also going on and off, sometimes small glow, other times bright bulb. Put an overhaul kit in the alternator, same result. Found a new 105 amp S10 ACDelco 3 wire alternator on ebay for $53, so ordered it. Autozone wanted $130 for a remanufactured 65 amp 1 wire. No 3 wire available. Would have to special order a 3 wire at increased cost. Tractor has always been a 3 wire since 12 volt conversion. Also noted that at times the amp gauge on the instrument panel would peg out. New alternator came in today. Needed some alterations. Had to change the clock position of the 2 wire plug from 3 oclock to 12 oclock to miss governor rods. Had to file bottom mount to fit existing mounts, and drill out bottom mount to use existing hardware. I really hate dealing with the brush crap. Chased the little springs all over driveway with a magnet. Had to change new alternator pulley to the original Ford govenor pulley to use the heavier Ford 5/8 belt. 3 hours later, ready to install the new alternator. Started and ran great. The idiot light performed as designed, the amp meter on the dash never pegged, my concern using a 105 amp alternator, started at 15 amp charging rate and backed off to zero in 15 minutes. No fluctuation of voltage at the coil, a steady 13.2 volts. No miss, plenty of power. I have never run into this on any vehicle I have ever worked on. Electricity is a evidently a magical thing, not to be comprehended by ordinary folk. I don't understand how changing the alternator magically cleared up all the operating problems I was seeing. Just happy everything is back to normal.


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## Allen Mader (Nov 27, 2019)

Ed Williams said:


> Update. I thought I knew a lot about tractor electrical systems, conversions and rewiring. WRONG. Since the total rewire of the NAA after the critter incident, I have had a terrible time Keeping it running. Hard starting, occasional misfire to varying cylinders, etc, etc. Wound up doing another complete rewire with new wire. Thought some of the old wire might be corroded inside causing the problem. After 2 weeks of steady work on it, the same results. Compression good, fuel good, good spark on all cylinders, but won't run without misfire and no power. I sat for 2 solid hours with voltmeter hooked to positive side of the coil. Volt readings ran from 4v to 13v, very intermittant. WHAT the Hell. The idiot light on the exciter line to the alternator was also going on and off, sometimes small glow, other times bright bulb. Put an overhaul kit in the alternator, same result. Found a new 105 amp S10 ACDelco 3 wire alternator on ebay for $53, so ordered it. Autozone wanted $130 for a remanufactured 65 amp 1 wire. No 3 wire available. Would have to special order a 3 wire at increased cost. Tractor has always been a 3 wire since 12 volt conversion. Also noted that at times the amp gauge on the instrument panel would peg out. New alternator came in today. Needed some alterations. Had to change the clock position of the 2 wire plug from 3 oclock to 12 oclock to miss governor rods. Had to file bottom mount to fit existing mounts, and drill out bottom mount to use existing hardware. I really hate dealing with the brush crap. Chased the little springs all over driveway with a magnet. Had to change new alternator pulley to the original Ford govenor pulley to use the heavier Ford 5/8 belt. 3 hours later, ready to install the new alternator. Started and ran great. The idiot light performed as designed, the amp meter on the dash never pegged, my concern using a 105 amp alternator, started at 15 amp charging rate and backed off to zero in 15 minutes. No fluctuation of voltage at the coil, a steady 13.2 volts. No miss, plenty of power. I have never run into this on any vehicle I have ever worked on. Electricity is a evidently a magical thing, not to be comprehended by ordinary folk. I don't understand how changing the alternator magically cleared up all the operating problems I was seeing. Just happy everything is back to normal.


Could,it be the distributor?


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## pogobill (Jan 31, 2012)

I have an oil cup on some of my distributors, and a grease cup on one of my others. Have a look.


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## Allen Mader (Nov 27, 2019)

pogobill said:


> I have an oil cup on some of my distributors, and a grease cup on one of my others. Have a look.


Hope that is the problem. I am not a chemical engineer but I have to tell you that you are only 3 days older than me. Making black powder would be something I would be interested in for the same purposes you mentioned, especially the model rockets for the grand kids!


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## Allen Mader (Nov 27, 2019)

Ed Williams said:


> Update. I thought I knew a lot about tractor electrical systems, conversions and rewiring. WRONG. Since the total rewire of the NAA after the critter incident, I have had a terrible time Keeping it running. Hard starting, occasional misfire to varying cylinders, etc, etc. Wound up doing another complete rewire with new wire. Thought some of the old wire might be corroded inside causing the problem. After 2 weeks of steady work on it, the same results. Compression good, fuel good, good spark on all cylinders, but won't run without misfire and no power. I sat for 2 solid hours with voltmeter hooked to positive side of the coil. Volt readings ran from 4v to 13v, very intermittant. WHAT the Hell. The idiot light on the exciter line to the alternator was also going on and off, sometimes small glow, other times bright bulb. Put an overhaul kit in the alternator, same result. Found a new 105 amp S10 ACDelco 3 wire alternator on ebay for $53, so ordered it. Autozone wanted $130 for a remanufactured 65 amp 1 wire. No 3 wire available. Would have to special order a 3 wire at increased cost. Tractor has always been a 3 wire since 12 volt conversion. Also noted that at times the amp gauge on the instrument panel would peg out. New alternator came in today. Needed some alterations. Had to change the clock position of the 2 wire plug from 3 oclock to 12 oclock to miss governor rods. Had to file bottom mount to fit existing mounts, and drill out bottom mount to use existing hardware. I really hate dealing with the brush crap. Chased the little springs all over driveway with a magnet. Had to change new alternator pulley to the original Ford govenor pulley to use the heavier Ford 5/8 belt. 3 hours later, ready to install the new alternator. Started and ran great. The idiot light performed as designed, the amp meter on the dash never pegged, my concern using a 105 amp alternator, started at 15 amp charging rate and backed off to zero in 15 minutes. No fluctuation of voltage at the coil, a steady 13.2 volts. No miss, plenty of power. I have never run into this on any vehicle I have ever worked on. Electricity is a evidently a magical thing, not to be comprehended by ordinary folk. I don't understand how changing the alternator magically cleared up all the operating problems I was seeing. Just happy everything is back to normal.


Yah Ed, I am not a chemical engineer but you are 3 days older than me. I would like to know more about black powder for the purpose of model rockets with the grand kids. Maybe some times when we get mad at our tractors we can just blow them up! ))


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## Ed Williams (Jun 13, 2019)

Allen Mader said:


> Could,it be the distributor?


The distributor looked fine. No play at all in any direction. Minev has the oil cup that I check weekly and add as needed. That still doesn't explain why installing a new alternator fixed all the problems I have been fighting. Fluctuating voltage on the primary side of the coil, intermittant spark, no power at all, ( it would not pull itself up a small hill next to the barn, had to side hill and switchback to get it back to the shed) Now it pulls the same hill in 3rd gear with a 200 rpm loss. I stii don't understand how the alternator change affects this. I forgot to mention that when this all started I installed new points, condenser, distributor cap, rotor button, dust shield, plug wires, and spark plugs. That had no effect at all.


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## Allen Mader (Nov 27, 2019)

Wiring and wires ???? Not my specialty. Plumbing I can see. So you are saying that the ford runs fine now? I hope a I never have to deal with a major electrical or plumbing problem on my Holder Tractor pictured. This week I dismantled a parts holder I bought for parts. Lots of hydraulic hoses, and wires. It had two fuse blocks with about 8 fuses in each. The guy I bought the running Holder had a problem with the marker lights on the left side , so he put a bigger fuse in it. I had problems with it also and finally found a bare wire touching the frame.


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## Ed Williams (Jun 13, 2019)

Allen Mader said:


> Yah Ed, I am not a chemical engineer but you are 3 days older than me. I would like to know more about black powder for the purpose of model rockets with the grand kids. Maybe some times when we get mad at our tractors we can just blow them up! ))


The black powder I make is specifically for black power firearms. It uses high quality components and takes 48 hours to process a batch (1.5 pounds) from start to finish. It is also rated "explosive grade". It works great in black powder guns, but not so well for model rockets. I had to cut it with 40% powdered sugar and enlarge the typical nozzle orifice fro 5/16 to 7/16 to get a controlled rocket burn and not an explosion. The neighbors thought I was making home made fireworks instead of rocket motors until I hit the right combination. For model rockets, the sugar engine is a safer alternative and eliminates the specialized milling process and home made charcoal retort process required for high grade black powder. Go to www.kingofrandom.com for full details on the reusable sugar rocket motor made from readily available materials, and links to free DIY rocket and launcher plans. There is also a YouTube video demonstrating the process. Do a google search "sugar rockets" and the video will pop up. The grandkids will love making their own rockets, motors and launch pans, but grandpa needs control of the match igniters for the motors.


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## Allen Mader (Nov 27, 2019)

Ed Williams said:


> The black powder I make is specifically for black power firearms. It uses high quality components and takes 48 hours to process a batch (1.5 pounds) from start to finish. It is also rated "explosive grade". It works great in black powder guns, but not so well for model rockets. I had to cut it with 40% powdered sugar and enlarge the typical nozzle orifice fro 5/16 to 7/16 to get a controlled rocket burn and not an explosion. The neighbors thought I was making home made fireworks instead of rocket motors until I hit the right combination. For model rockets, the sugar engine is a safer alternative and eliminates the specialized milling process and home made charcoal retort process required for high grade black powder. Go to www.kingofrandom.com for full details on the reusable sugar rocket motor made from readily available materials, and links to free DIY rocket and launcher plans. There is also a YouTube video demonstrating the process. Do a google search "sugar rockets" and the video will pop up. The grandkids will love making their own rockets, motors and launch pans, but grandpa needs control of the match igniters for the motors.


Thanks Ed. Hope the moderator does not correct us for being off base with the thread. )). I will have my grand kids for a couple of weeks since the schools will be closed. It will be fun to have a few chemistry lessons, plus plenty of tractor work to get some wood out of the woods that I have been cutting all winter in uppermost Wisconsin. Still have about 18 inches on the ground and I did get stuck with my 1070 John Deere with the loader. Snow is very granular now and I do not have chains. Best to just stay out of the woods until the snow goes and it dries up or the snow pack goes down and it freezes up again. Ed check this guy out. He is a logger I know and has a story. Will To Live Gary Edinger.


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## Ed Williams (Jun 13, 2019)

Allen Mader said:


> Thanks Ed. Hope the moderator does not correct us for being off base with the thread. )). I will have my grand kids for a couple of weeks since the schools will be closed. It will be fun to have a few chemistry lessons, plus plenty of tractor work to get some wood out of the woods that I have been cutting all winter in uppermost Wisconsin. Still have about 18 inches on the ground and I did get stuck with my 1070 John Deere with the loader. Snow is very granular now and I do not have chains. Best to just stay out of the woods until the snow goes and it dries up or the snow pack goes down and it freezes up again. Ed check this guy out. He is a logger I know and has a story. Will To Live Gary Edinger.


Ran across that a while back, Truely amazing.


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## Allen Mader (Nov 27, 2019)

I may have posted about Gary before but you are the only person who acknowledged that watched the video. Went for a ride in my home built airplane today with skis. Landed on a lake and just about rattled my teeth out, since the ice was very rough. I would imagine pogo’s tractor with the half tracks and skis would be slower and smoother.


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## FredM (Nov 18, 2015)

You dont think the old alternator may have shorted out after the chewing the wiring got ??, this would be the most likely culprit to cause the voltages to change as you done your tests.


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## Ed Williams (Jun 13, 2019)

FredM said:


> You dont think the old alternator may have shorted out after the chewing the wiring got ??, this would be the most likely culprit to cause the voltages to change as you done your tests.


That looks like the case right now. Electrical problems confuse me a little. I know just enough to be dangerous. Basic wiring I do okay, but shorts and open circuits can be confusing. The alternator pegging the amp meter was a red flag that something was amiss.


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