M1008 Battery NOT charging issues... GRRRR

[MilitarySurplusBrent]

So, I have a 86 M1008 ALL stock w/24v system, two new Interstate batteries (use these on all my CUCV's). When I got the new batteries it would start very easily. But now after a few months and I have maybe put 20 miles on it since then, the gauge is in the Red (with lights on) / Yellow (goes up a little bit in the yellow with no lights on), it seems like the system is de-charging the new batteries. My 1st GEN light on the dash is not working, changed the bulb and still isn't working, checked the 10 amp fuse under the dash, it's OK, I checked the cables and they look good, I haven't had a chance to check the voltage yet on the ALTS but hopefully will do in a few days when I get a chance. Anyways, I know there's a few posts on this issue. I THINK & hope it's just the pass side alt needs to be rebuilt, or something stupid I'm not looking over.

Anything else I could check before I test the ALT's? Any help would be great! Thanks Brent!

 

[Warthog]

The GEN1 and GEN2 bulbs have to be working in order for the alternators to work. That is part of the circuit design.

Use you multimeter to check the voltages at both batteries with the truck off and running.

 

[MilitarySurplusBrent]

The GEN1 and GEN2 bulbs have to be working in order for the alternators to work. That is part of the circuit design.

Use you multimeter to check the voltages at both batteries with the truck off and running.

I'll check it out later today, I also noticed on another post you replyed to that the about the " Isolated Ground" is a issue and I seen that picture you had of the drivers side alt had the ground hooked up to the post, I think mine is hooked to the back NON post of the ALT

 

[MilitarySurplusBrent]

 

[cucvrus]

I would remove the cluster or crawl under the dash and work on the cluster. Whatever you need to do. But most times it is just a little corrosion or a loose bulb in one of the bulb holders. Check all your fuses and go at it. Once you have the idiot lights working as designed you should have both alternators charging as designed. It sounds easier then it is but it is worth the effort and while you are at it get all the lights in the cluster to work. It will make a world of difference when night driving to have the cluster illuminated as designed.

 

[MilitarySurplusBrent]

Mine is here in the yellow box, sorry for the BAD drawing... haha

 

[Warthog]

That will cause the alternator to not work.

drawing can't be any worst that many of mine.

 

[MilitarySurplusBrent]

I would remove the cluster or crawl under the dash and work on the cluster. Whatever you need to do. But most times it is just a little corrosion or a loose bulb in one of the bulb holders. Check all your fuses and go at it. Once you have the idiot lights working as designed you should have both alternators charging as designed. It sounds easier then it is but it is worth the effort and while you are at it get all the lights in the cluster to work. It will make a world of difference when night driving to have the cluster illuminated as designed.

I totally agree, I will remove the cluster and "rebuild" it with new bulbs, clean all the connections, polish the face and put everything back together. I'm one of those type of people that does it RIGHT the 1st time and make sure it works. Cutting corners is not in my blood... Again, thanks for all the help so far!

 

[MilitarySurplusBrent]

warthog, hey at least we can draw stick figures well ! I'll take that connector off, put it on the post where it should be (according to your awesome drawing), and fix the cluster bulb. I think I was there figuring it out, but needed to make sure I was on the right path and not seeing... SQUIRREL! Sorry i got distracted HAHA.

 

[cucvrus]

The good thing about rebuilding the cluster is that you have enough slack in the wiring harness to do all the repairs with the harness hooked up. I unload everything out the front of the cluster and reinstall everything back in thru the front as you are putting it back together and double checking everything as you go. It saves you from taking it in and out several times and finding other lights that don't work. It is easier this way. Trust me. Always worked for me. I used to put a blanket over it and climb in and out and see if the bulbs were all lit. That was to time consuming. I agree do it right the 1st time and it is as good as new. I repaired mine about 8 years ago and everything still works. And I did not get fancy and convert it to red lights, green lights, or LED just the way it was works for me. It worked that way for 25 years before I got it.

 

[cpf240]

Be sure to disconnect the batteries! It is very easy to short out the always hot 24v wire connected to the volt gauge!

 

[cucvrus]

It is going to be a little hard to check if the cluster lights are working with the battery disconnected. Just unplug the volt meter and be careful. If the voltmeter works it don't need to be corrected.