Periodic charging system issues

So I’m getting ready to move from SC to WV next week which means hauling my 40 foot 5th wheel, so I need to make sure I’m ready to go. Just yesterday, my charging system light came on along with the check gauges light (no codes).

The charging system appears to be only putting out 12.5 volts most times. If I start it a few times, it will sometimes be normal and go back up to 14, but that’s very sporadic. No belt noise, no alt noise, any ideas? Is there a clutch on the alt that could be the issue?

On a side note, I did notice my coolant temp sensor is cracked while I was looking at the alt, but I don’t think that would have any effect on charging?

I could def use some input...

It’s an 08 Cummins 2500

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Originally Posted by Nooch13

It’s an 08 Cummins 2500

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Take the fuse block out, remove the plugs, check for corrosion. Start pulling all the fuses and put them back in. Best to put some silicone grease or vaseline on all the fuses and connections.

Further, pull the alternator and have it checked. Stay away from Auto Zone. Carquest, NAPA are a better bet for a correct answer and people that have a partial clue

BTW I just had a ABS issue because of a bad plug on my fuse block. I knew to go there first. Solved the problem immediately. I have a broken latch on one of the harness's.

Best to disconnect the batteries before you start this

Thanks, I will pull all the fuses, but how the heck do you get the whole fuse box out? I can get the red clip loose but it’s surrounded by a while handle that won’t budge...

Like @Polaraco said, pull the alternator and have it tested, much quicker and easier than pulling the fuse block.
I just replaced mine on a 2011, I was in the same situation, low output at times, at other times, no issue... Until one day it just died and left me dead in a parking lot... I took it to 2 different shops and neither could could get a reading from it.
Ended up going with an 180amp one from http://www.nationsstarteralternator.com/ at the suggestion of @HKBIGDADDYDIESELDAN
Wasnt cheap, but it's made in the USA and new, not a reman.

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Originally Posted by 4kids2dogs&RV

Like @Polaraco said, pull the alternator and have it tested, much quicker and easier than pulling the fuse block.
I just replaced mine on a 2011, I was in the same situation, low output at times, at other times, no issue... Until one day it just died and left me dead in a parking lot... I took it to 2 different shops and neither could could get a reading from it.
Ended up going with an 180amp one from http://www.nationsstarteralternator.com/ at the suggestion of @HKBIGDADDYDIESELDAN
Wasnt cheap, but it's made in the USA and new, not a reman.

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Damn kids. It pays to be old sometimes. LOL (just kidding)

There were spotty corrosion issues with the fuse blocks on the late 3rd gens. That's why I suggested that first.
@Nooch13 There's a ton of used. They are usually very good and probably last longer than todays rebuilts

So update, the alternator was bad. Got the new one in, but how the hell do you start this serpentine belt???

Got it, but damn! That belt was a beast!!

Quote:

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Originally Posted by Nooch13

So update, the alternator was bad. Got the new one in, but how the hell do you start this serpentine belt???

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Good deal!

Hopefully it was easier than replacing the fuse block

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