Alternator changeout issues

[charlesmann]

Battery voltage is 12.7 for a fully charged 12 volt battery. X2 for 24 volt system or 25.4 for a 24 volt battery pack. Either you are measuring wrong or the alternator isn't working.

Im not measuring wrong. The alt might not be running at full power, but its producing just enough to keep them topped off. Those voltage numbers were also before driving it. After driving it with all lights on, the voltage was 24.7. So its safe to assume its trickling just enough volts to top off.

 

[Tow4]

Im not measuring wrong. The alt might not be running at full power, but its producing just enough to keep them topped off. Those voltage numbers were also before driving it. After driving it with all lights on, the voltage was 24.7. So its safe to assume its trickling just enough volts to top off.

12.35 volts per battery is not topped off, it's a 60~70% charge. Not keeping the batteries fully charged will lead to premature battery failure.

 

[kendelrio]

Disconnect the power wire from the alternator and run an Independent wire from the alternator to the starter lug for the power. Delete the pcb from the charging system

Great troubleshooting tip right here. It takes the truck completely out of the circuit and removed the draw.

Thanks to you and @74M35A2 for all of the help!

 

[74M35A2]

Great troubleshooting tip right here. It takes the truck completely out of the circuit and removed the draw.

Thanks to you and @74M35A2 for all of the help!

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Glad you have it figured out, new alternator works proper, and high indicated voltage was causes by weak voltmeter batteries.

 

[charlesmann]

How often is it the voltage regulator is the cause of low voltage output? the pull off alt from my parts truck shows 4.08v dc, 3 volts higher than the alt that came off the truck. I see that eastern surplus has a voltage regulator for sale https://www.easternsurplus.net/PartDetails/5455/COM-5360-Voltage-Regulator and if those go out more so than the stator, then could it be beneficial to just replace the faulty part, instead of the whole thing?

Is there a way to check the power going into the regulator, and if so, which of the terminals to i check from?

 

[74M35A2]

How often is it the voltage regulator is the cause of low voltage output? the pull off alt from my parts truck shows 4.08v dc, 3 volts higher than the alt that came off the truck. I see that eastern surplus has a voltage regulator for sale https://www.easternsurplus.net/PartDetails/5455/COM-5360-Voltage-Regulator and if those go out more so than the stator, then could it be beneficial to just replace the faulty part, instead of the whole thing?

Is there a way to check the power going into the regulator, and if so, which of the terminals to i check from?

Sorry, I don’t support the antiquated stock alternators at all. They have 4 common main failure modes, and the modern ones have fail-safe strategies integrated into them. They just work perfect, are low cost, and enable you to shut the truck off safely in any switch order.

Others here may have some diagnostic and troubleshooting tips for the stock alternator. I do like the way it looks though…. :/

 

[charlesmann]

Looks like the gold colored resistor is blown. This is off the parts truck. The following are from the “original” alt.



The disconnected wire looks to be disconnected from just above the loose wire in the last photo. That connection looks to be the wire’s “natural” point of rest.
Blown resistor on 1, broken wire on the other is probably a good indicator of why its not putting out 28 volts.

 

[charlesmann]

After stripping the insulation back from where i thought the wire goes, i could see that it indeed was crimped with another wire. While trying to solder the wire to the terminal, i inadvertently, desoldered the other end. Gotta strip some more insulation tomorrow and try to solder everything back in place.

Im thinking of hang testing the “good” regulator on the alt with the blown resistor and hope that works. The worst that happen is neither alt work and i have buy another one.

 

[papakb]

Those resistors are 50 ohm, 50 watt units. I have a pretty good stock of them if you want to replace it. PM if interested.

Kurt

 

[charlesmann]

Those resistors are 50 ohm, 50 watt units. I have a pretty good stock of them if you want to replace it. PM if interested.

Kurt

Let me see if that is the issue with that alt, by using the other regulator. if it works, then i'll reach out for a replacement resistor, and hopefully i can get the other alt soldered back, then i'll hang test it, and hopefully all is well.

 

[charlesmann]

Well, soldering wire #2 from the regulator to the connection point of where it was broke off from seemed to fix the no charging. I was hesitant at first since i was getting OL on my meter without the output wire connected. I said screw it, what could go wrong and connected the output wire, turned the lights on and walked away. I was showing 25.7 volts at the batteries before connecting the alt output wire. I came inside to do some research as to svc/running light bulb numbers and switching to LED bulbs. 20 min later, i went back to check voltage, figuring i would be 24v or less, but not so. At the alt, it was producing 28.4 volts and when i checked the batteries, i had 27.2 volts. My charge gauge was showing on the line of yellow and green with lights on, and when i turned them off, it jumped into the green.

Now troubleshoot why none of the svc/running lights come on when switch set to svc/park, but when i switch to drive, all lights except both front svc/park lights come on, but I do have front turn signals. Thinking about switching all lights to plug/play LEDs, except for the headlights right now.

 

[kendelrio]

Now troubleshoot why none of the svc/running lights come on when switch set to svc/park, but when i switch to drive, all lights except both front svc/park lights come on, but I do have front turn signals. Thinking about switching all lights to plug/play LEDs, except for the headlights right now.

Great job on the fix! I can't speak to the other issues, but I know our front blinkers don't act as parking lights... at least as far as I have been able to find.

 

[charlesmann]

Great job on the fix! I can't speak to the other issues, but I know our front blinkers don't act as parking lights... at least as far as I have been able to find.

correct, they do not. there are 3 bulbs in the front and rear light housings, 1 is park/svc/running light, turn/brake and BO drive on the very bottom. I was going to clean the side maker lens, noticed the bulb receptacle was heavily corroded, ended up robbing from the other truck bc i twisted the bulb from the bulb housing. I used some of that anti-corrosion paste and put on the receptacle gnd and some in the packard connectors. I was getting a very dim illumination on both the side marker and svc/park bulb, and when i went to put the turn/svc lens cover on, the lights brightened up, as if it was a bad ground, and both L and R front svc bulbs were brightly illuminated. Then i started messing with the packard connectors, and the front svc bulbs went out again. So I'm assuming its a ground issue. I do need to source some more packard connectors to replace ALL my front lighting connectors, since the rubber is falling apart. I will start messing the front lighting ground/s, cleaning them and getting a know good ground and hope that solves the issue. I freakin HATE electrical.

 

[74M35A2]

correct, they do not. there are 3 bulbs in the front and rear light housings, 1 is park/svc/running light, turn/brake and BO drive on the very bottom. I was going to clean the side maker lens, noticed the bulb receptacle was heavily corroded, ended up robbing from the other truck bc i twisted the bulb from the bulb housing. I used some of that anti-corrosion paste and put on the receptacle gnd and some in the packard connectors. I was getting a very dim illumination on both the side marker and svc/park bulb, and when i went to put the turn/svc lens cover on, the lights brightened up, as if it was a bad ground, and both L and R front svc bulbs were brightly illuminated. Then i started messing with the packard connectors, and the front svc bulbs went out again. So I'm assuming its a ground issue. I do need to source some more packard connectors to replace ALL my front lighting connectors, since the rubber is falling apart. I will start messing the front lighting ground/s, cleaning them and getting a know good ground and hope that solves the issue. I freakin HATE electrical.

New thread.

 

[papakb]

For Heaven only knows what reason the composite lights on military vehicles ground thru BOTH mounting holes. There should be a small strap that goes between them to make sure they both see a good ground. Forget the strap and you get all kinds of wierd electrical issues. Make sure the connections are clean (corrosion free) and the bolts are tight. It never hurts to put some silicon lube (not RTV) down in the bolt holes when you mount them to exclude moisture form betting inside.

 

[Guyfang]

papakb,

I am not a truck guy, but had to work on them sometimes. I always added a serrated washer on there because it always seemed to help a bit. Just my two cents.

 

[papakb]

When you do radio installations you always use those star washers because they bite through the paint and dig into the metal giving a good ground. If you have them they're a good guarantee but they can be hard to find sometimes. I know that McMaster-Carr sells them and they're not that expensive: www.mcmaster.com/star-washers/internal-external-tooth-lock-washers/

 

[Guyfang]

They are a must on the 5 and 10 KW, MEP-002A and MEP-003A. Without them, these very reliable gen sets turn into junk. Problems without end. We discovered in the late 70's, that just these two sets seemed to NEED them. Strange. I kept three different sizes, and 100 pieces per size. When ever we got Float material, or later at DS level when we got repair jobs in, if there were no serrated washer on them when they came in, they were there when they left shop.

 

[Mullaney]

They are a must on the 5 and 10 KW, MEP-002A and MEP-003A. Without them, these very reliable gen sets turn into junk. Problems without end. We discovered in the late 70's, that just these two sets seemed to NEED them. Strange. I kept three different sizes, and 100 pieces per size. When ever we got Float material, or later at DS level when we got repair jobs in, if there were no serrated washer on them when they came in, they were there when they left shop.

.
Those star washers - especially with small nuts and bolts - seem to do especially well on vehicles that vibrate like a GenSet. We used them on radios in the old Bouligny radio installations... Made all the difference in the world for us.

 

[Mitchkrat]

Great troubleshooting tip right here. It takes the truck completely out of the circuit and removed the draw.

Thanks to you and @74M35A2 for all of the help!

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where did you purchase your new alternator?