Hmmwv charging problem

[001666100]

I have a '91 hmmwv. It has a 200amp generator. I've been noticing the battery gauge is always in the yellow and never switches to the green gen mode. I took the batteries out and charged them individually truck starts and runs fine no issues. I've checked the 28v and 14v post on the generator and there is no voltage so my guess was that I have a bad generator. I bought a tested refurbished 200amp gen and put it in still no voltage output not charging the batteries. I also tried removing the ground cable from the batteries when the truck was running because to my understanding if the generator is working the truck should still run and it did not turned off right away. So I still think it may be the generator maybe the supposed tested refurbished generator was no good or am I missing something is? Would the EESS have something to do with this? To my understanding if the generator is running even if there is other issues in the truck if you take a reading at the generator on the 14v or 28v post to ground it should have an output voltage if it's working. Can someone please help?

 

[orgnal]

I have a '91 hmmwv. It has a 200amp generator. I've been noticing the battery gauge is always in the yellow and never switches to the green gen mode. I took the batteries out and charged them individually truck starts and runs fine no issues. I've checked the 28v and 14v post on the generator and there is no voltage so my guess was that I have a bad generator. I bought a tested refurbished 200amp gen and put it in still no voltage output not charging the batteries. I also tried removing the ground cable from the batteries when the truck was running because to my understanding if the generator is working the truck should still run and it did not turned off right away. So I still think it may be the generator maybe the supposed tested refurbished generator was no good or am I missing something is? Would the EESS have something to do with this? To my understanding if the generator is running even if there is other issues in the truck if you take a reading at the generator on the 14v or 28v post to ground it should have an output voltage if it's working. Can someone please help?

When the truck is running, the generator should be putting out 28v and 14v at the respective posts on the generator. I guess it would be safe to assume you had the circuit closed i.e. the negative of the voltmeter connected to the HMMWV body and the negative of the generator is grounded properly to the HMMWV body. Then you have bad generator(s).

McReddy

 

[86humv]

If your truck is a V belt motor...and if your regulator looks like my pic then :
the 14v tap goes to ground if reg. looks like the one on right.
If like left one, then no grounding needed [ yellow terminal ].
Usally the reg. goes bad before the Alt.

 

[mechanicjim]

have you tested the IGN wire going to the Regulator? also Niehoff has trouble shooting guides for their alternators on their website under service and support. look up you model alternator (NXXX) and see if you find a fault with your unit, it should give you a better idea of what is going on than just no output.