Battery not charging

[Tylerl66]

I have dug and dug on this with no luck.

Im not one to start a new thread but I feel it's best.

I acquired an 86 m1009 6.2 a couple weeks ago.
All it needed was two new batteries and it fired up!
(My first military vehicle) all stock

Well after causing it around a few days I noticed my battery gauge wasn't working at all (previously it only went into the yellow) I didn't think much of it, just figured the gauge was out.

Slow blinkers, slow wipers are some other things I noticed. My first older truck I didnt know of that was normal or not.

Finally it one morning it cranked but the fasten seat belt light wouldnt go off.
I killed it in a drive thru line and it wouldn't crank back up until it was jumped.
After jumping it I had 0 lights at all (and it wasn't in off or black out mode)

When I started looking at it I noticed the front battery wasn't charging at all it had 8volts.
I checked the back of the driver side alternator and it matched what the battery read (8volts)

I bought two wilson alternators part #90014277
And new belts. Got every thing installed jumped it off and still nothing.
Not charging the front battery, front battery is draining as it runs.
Driver side alternator is still mirroring the voltage of front battery.
Still no lights.

Back battery is just fine to my knowledge



My plan tomorrow is clean all connections and get belts even tighter

 

[Trailgator]

You are aware that the Alternators are not the same and that one of them has an isolated ground for he 12/24 volt system aren’t you?

 

[Tylerl66]

You are aware that the Alternators are not the same and that one of them has an isolated ground for he 12/24 volt system aren’t you?

Yes I am

I had the same issue before changing the alternator as I do after

Everything was plugged back up the same

 

[Curtisje]

When you turn the key on prior to starting the engine do the Gen1 & Gen2 lights come on?

 

[cucvrus]

Good one. But it will still kick in a charge with higher RPM's. I have an M1028 that I use as my hauler of unwanted things and it has no Gen light. Rev it up and it charges normal. Tiered of looking for the issue and it has never been apart and I don't plan on fixing it as long as it works they way it does. I have to much other stuff to keep me busy. Take Care. Make sure the ground wire is on the Gen 1 to the engine block. Just being an isolated ground alternator does nothing if the isolator is not grounded.

 

[Tylerl66]

Its up running and charging!

I cleaned the plug by the fire wall (heater plug?)
Cleaned gen 1 and 2 bulb connections along with new bulbs.
And replaced red and brown wire connection on driver side alternator!

Gen 1 and 2 lights come on and now go off when running (which I assume is right)

Only thing now is battery gauge is intermittent

 

[Curtisje]

Good one. But it will still kick in a charge with higher RPM's. I have an M1028 that I use as my hauler of unwanted things and it has no Gen light. Rev it up and it charges normal. Tiered of looking for the issue and it has never been apart and I don't plan on fixing it as long as it works they way it does. I have to much other stuff to keep me busy. Take Care. Make sure the ground wire is on the Gen 1 to the engine block. Just being an isolated ground alternator does nothing if the isolator is not grounded.

Seemed like a good place to start with what little information we had but we did know his alternator wasn't charging.