Gen 2 Light Stays On While Engine is Running

[jplace1011]

What the heck did I do? I was cleaning the plugs for the alternators of my M1009. I accidentally made contact with my tiny screw driver and a plug prong in the alternator on the passengers side. A spark or two flew.

I first checked all of the fuses, none were blown. The Gen 2 Light is now on whenever I start the vehicle. The Fuel Gauge Stopped working too. Did I blow a Relay, did I destroy the alternator??

I suspect this has been asked before, I’ll be digging again in the TMs but you guys are much more helpful.

Thanks for any help!

The plugs really needed cleaning!!

 

[WWRD99]

did you check voltage at that plug yet? Also did you check the wires up at the fuse block on top by the batteries? Probably fried a link...pull on them and see which one comes apart and replace it.

 

[jplace1011]

did you check voltage at that plug yet? Also did you check the wires up at the fuse block on top by the batteries? Probably fried a link...pull on them and see which one comes apart and replace it.

Thanks for getting back to me. I’m still learning so bare with me please.

Are you meaning these black pieces with numbers at the ends of the wires? I’m guessing there might be fuses inside? Maybe I’m way off.

Thanks again for any help.

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[WWRD99]

Thanks for getting back to me. I’m still learning so bare with me please.

Are you meaning these black pieces with numbers at the ends of the wires? I’m guessing there might be fuses inside? Maybe I’m way off.

Thanks again for any help.

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yup those little buggers are meant to let the smoke out but look fine...sometimes if they burn good you can just pull on them and they come apart...another good thing about pulling on them is you may find one that isn't burned all the way that isn't related to what you have going on but needs replaced...you can install a replaceable fuse link in there if you want...fusible links can be tough to find unless you hit a napa or a shop style parts store.

 

[jplace1011]

yup those little buggers are meant to let the smoke out but look fine...sometimes if they burn good you can just pull on them and they come apart...another good thing about pulling on them is you may find one that isn't burned all the way that isn't related to what you have going on but needs replaced...you can install a replaceable fuse link in there if you want...fusible links can be tough to find unless you hit a napa or a shop style parts store.

I think I’m starting to understand. I’ll pull on all of those near the back of the engine compartment. As well as the one I found near the alternator. I had no idea about these or how they work.

I will look at Napa today for new links.

Does the number on the tubing represent the wire gauge of the fusible link? If it does, I’m guessing you look for that number of fusible link when purchasing a new one?

Thank you very much, you’re helping me so much.


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[WWRD99]

I think I’m starting to understand. I’ll pull on all of those near the back of the engine compartment. As well as the one I found near the alternator. I had no idea about these or how they work.

I will look at Napa today for new links.

Does the number on the tubing represent the wire gauge of the fusible link? If it does, I’m guessing you look for that number of fusible link when purchasing a new one?

Thank you very much, you’re helping me so much.


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If I remember right yes on the number...if you look at your last pic you can see the yellow 20 gauge wire with fusible link written on it...the pull method works but just to be sure you need to check for volts with a test light or meter...the pull method is great for quick checks or roadside repairs!! If the wire insulation stretches though then it is gone inside.

 

[Mullaney]

I think I’m starting to understand. I’ll pull on all of those near the back of the engine compartment. As well as the one I found near the alternator. I had no idea about these or how they work.

I will look at Napa today for new links.

Does the number on the tubing represent the wire gauge of the fusible link? If it does, I’m guessing you look for that number of fusible link when purchasing a new one?

Thank you very much, you’re helping me so much.


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.
The number on the "black rubber looking thing" (fused link) is amps (generally 20, 30 or 50 amps). They work just like a blade or glass fuse would - except the links are a one time "burn up and die" operation. Only reason it matters is that the links are a "slow blow" variety of fuses...

 

[jplace1011]

.
The number on the "black rubber looking thing" (fused link) is amps (generally 20, 30 or 50 amps). They work just like a blade or glass fuse would - except the links are a one time "burn up and die" operation. Only reason it matters is that the links are a "slow blow" variety of fuses...

Thank you!! I’ll check the wires now. I’ll have to figure out the size if one is blown. I have to go to Napa anyways, so it will work out.

The Fuel Gauge stopped working after this incident. If it still doesn’t work after this fusible link stuff I may hit you guys up again.

First things first!


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[jplace1011]

Thank you!! I’ll check the wires now. I’ll have to figure out the size if one is blown. I have to go to Napa anyways, so it will work out.

The Fuel Gauge stopped working after this incident. If it still doesn’t work after this fusible link stuff I may hit you guys up again.

First things first!


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I pulled on each fuse link. Nothing seemed loose or wanted to give. Not sure if that means none are blown or what.

Not sure what to do next?? Is there another way to test the fusible links?

p.s. One of you said to test the alternator plug. How exactly do I do that? I’m still learning, bare with me.


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[Curtisje]

I pulled on each fuse link. Nothing seemed loose or wanted to give. Not sure if that means none are blown or what.

Not sure what to do next??

p.a. One of you said to test the alternator plug. How exactly do I do that? I’m still learning, bare with me.


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I think it my be esier for you to pull the alternator, take it to your local parts store and have them test it. Just be sure to disconnect the batteries first. Either way good luck.

 

[Skinny]

Check your charging voltage in the truck with it running. It will only tell you the truth.

Solid chance you may have popped the regulator by shorting it. Those plugs can be found anywhere. Simple fix, be sure to use a quality heat shrink but connector. If you are selling your truck then use wire nuts...it never stopped anyone. That's a joke...

If your alternators haven't been rebuilt take this experience and use it as an excuse to thoroughly go through them anyway.

 

[jplace1011]

Check your charging voltage in the truck with it running. It will only tell you the truth.

Solid chance you may have popped the regulator by shorting it. Those plugs can be found anywhere. Simple fix, be sure to use a quality heat shrink but connector. If you are selling your truck then use wire nuts...it never stopped anyone. That's a joke...

If your alternators haven't been rebuilt take this experience and use it as an excuse to thoroughly go through them anyway.

Hi Skinny! I’ve seen your name in plenty of threads!

How exactly do I check the charging voltage in the truck?

As far as a regulator what is it called exactly and where is it located?

Sorry for all of the questions, I’m still learning and have a lot left to learn!

My alternators are rebuilt from Hillbilly Wizard, I had them put in last year.

Thanks for your input, I greatly appreciate it.


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[WWRD99]

Hi Skinny! I’ve seen your name in plenty of threads!

How exactly do I check the charging voltage in the truck?

As far as a regulator what is it called exactly and where is it located?

Sorry for all of the questions, I’m still learning and have a lot left to learn!

My alternators are rebuilt from Hillbilly Wizard, I had them put in last year.

Thanks for your input, I greatly appreciate it.


Sent from my iPhone using Tapatalk

You'll need a volt meter and see if your getting the 25 up volts while running...if you had the plug that you cleaned not plugged into the alternator when it sparked the regulator should be ok...that plug goes into the regulator.

 

[Skinny]

Hey

Good call, if it wasn't plugged in it's fine. So you are a step ahead of the game if they have been rebuilt.

Time to buy a voltmeter if you don't have one.

 

[jplace1011]

You'll need a volt meter and see if your getting the 25 up volts while running...if you had the plug that you cleaned not plugged into the alternator when it sparked the regulator should be ok...that plug goes into the regulator.

Thanks for getting back to me.

The Passengers Side Alternator was unplugged But I slightly touched where the plug goes inside the alternator. I guess that would be one of the prongs on the inside of the alternator. I think the side where the brown wire plug goes in. I can’t say for sure, but it could be that side, if it even matters.

With all that hopefully the Regulator is ok.? If needed, is there a way to test the regulator?

I do have a voltmeter, yes! You said to test if it has 25 volts up and running. What & How would I do that exactly? Test each battery before start up (add the numbers together) and then test each one after start up (add the numbers together)?

Thanks for your patience.


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[Tow4]

Thanks for getting back to me.

The Passengers Side Alternator was unplugged But I slightly touched where the plug goes inside the alternator. I guess that would be one of the prongs on the inside of the alternator. I think the side where the brown wire plug goes in. I can’t say for sure, but it could be that side, if it even matters.

With all that hopefully the Regulator is ok.? If needed, is there a way to test the regulator?

I do have a voltmeter, yes! You said to test if it has 25 volts up and running. What & How would I do that exactly? Test each battery before start up (add the numbers together) and then test each one after start up (add the numbers together)?

Thanks for your patience.


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When diagnosing a charging problem, test each alternator/battery combination separately. Each alternator/battery combination is it's own system as far as charging goes. That's the reason for the isolated ground. With the engine running they should have about 14.8 volts.

 

[MarcusOReallyus]

I do have a voltmeter, yes! You said to test if it has 25 volts up and running. What & How would I do that exactly? Test each battery before start up (add the numbers together) and then test each one after start up (add the numbers together)?

There are two ways to test any battery/alternator; running and not running. With the CUCV's 24v system, there are two ways to test your system, each individually, and the total output. That mutiples things. I'll lay it out:

Individually, with the engine stopped:

Measure from the negative post of the FRONT battery to the positive post of the FRONT battery.
Measure from the negative post of the REAR battery to the positive post of the REAR battery.

You should see about 13 volts on each battery.

Individually, with the engine running:

Measure from the negative post of the FRONT battery to the positive post of the FRONT battery.
Measure from the negative post of the REAR battery to the positive post of the REAR battery.

You should see about 14.8 volts on each battery.


Now, total system voltage goes like this:

Both together, with the engine stopped:

Measure from the negative post of the FRONT battery to the positive post of the REAR battery.


You should see about 26 volts.

Both together, with the engine stopped:

Measure from the negative post of the FRONT battery to the positive post of the REAR battery.


You should see about 29.6 volts. Pretty close to that, anyway.



As you can see, it's simpler to measure total voltage, and for a quick check, that's fine. But if you don't have enough jolts, you need to measure individually to see where the problem is. Maybe you have one alternator out, or maybe both. Can't tell until you measure individually.

Now, if you are troubleshooting, you may want to take some other measurements, like directly at the back of the alternator, for example. But this gets you the basics to start with.

 

[jplace1011]

There are two ways to test any battery/alternator; running and not running. With the CUCV's 24v system, there are two ways to test your system, each individually, and the total output. That mutiples things. I'll lay it out:

Individually, with the engine stopped:

Measure from the negative post of the FRONT battery to the positive post of the FRONT battery.
Measure from the negative post of the REAR battery to the positive post of the REAR battery.

You should see about 13 volts on each battery.

Individually, with the engine running:

Measure from the negative post of the FRONT battery to the positive post of the FRONT battery.
Measure from the negative post of the REAR battery to the positive post of the REAR battery.

You should see about 14.8 volts on each battery.


Now, total system voltage goes like this:

Both together, with the engine stopped:

Measure from the negative post of the FRONT battery to the positive post of the REAR battery.


You should see about 26 volts.

Both together, with the engine stopped:

Measure from the negative post of the FRONT battery to the positive post of the REAR battery.


You should see about 29.6 volts. Pretty close to that, anyway.



As you can see, it's simpler to measure total voltage, and for a quick check, that's fine. But if you don't have enough jolts, you need to measure individually to see where the problem is. Maybe you have one alternator out, or maybe both. Can't tell until you measure individually.

Now, if you are troubleshooting, you may want to take some other measurements, like directly at the back of the alternator, for example. But this gets you the basics to start with.

This is really great! I need step by step since I don’t have an experience with this sort of thing. Thank you thank you. I’ll do all of this and report my results.


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[jplace1011]

This is really great! I need step by step since I don’t have an experience with this sort of thing. Thank you thank you. I’ll do all of this and report my results.


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Well this doesn’t look good…

Not Running
Front Battery 12.72
Rear Battery 12.53

Together 25.1


Running
Front Battery 13.7
Rear Battery 12.3

Together 26.2

Maybe the Regulator for the passengers side alternator needs replace. That’s the area I accidentally tapped with the tiny screw driver.

I may be way off. I know you mentioned testing the back of the alternators as well.


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[Mullaney]

Well this doesn’t look good…

Not Running
Front Battery 12.72
Rear Battery 12.53

Together 25.1


Running
Front Battery 13.7
Rear Battery 12.3

Together 26.2

Maybe the Regulator for the passengers side alternator needs replace. That’s the area I accidentally tapped with the tiny screw driver.

I may be way off.


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.
Looks to me like the rear battery isn't being charged. AND the alternator attached to the rear battery isn't putting out enough voltage.

Any way you look at it, that back battery needs to be on a slow charge overnight. It should be showing 13+ running so the alternator "doing its thing". Regulator might be toast.