HMMWV Question

Hi, i got a M1097 and i have a charging problem. Batteries are good. Voltage at positive terminal on alternator is 23.89V and same thing @ the voltage regulator. My question is how do i tell if its the alternator or voltage regulator that is causing this low voltage problem? Thanks for looking

If using 60amp military generator, then adjust the output voltage to 28vdc with a voltmeter (military gauge is not accurate). On top of unit is an allen head plug. Remove and inside is a potentiometer. Use a small slot screwdriver and turn pot until you get 28vdc at the batteries. Then let charge and check again. Adjust if necessary.

*BECAREFUL OF BELTS AND PULLEYS AND LOOSE CLOTHING AND FINGERS!!!!!

I have a 200 amp alternator in it right now with 6.2L engine

The 200 amp is preset at the factory,it has no user adjustments....most likely the regulator.

The reg is solid state and not a servicable part. In the shop we use a "known good" reg for testing. 200A are newer dual voltage inductive (brush-less) if Im remembering correctly. Do you get any charging off the 12v lug? Not much that can fail on those alts except bearings and rectifier sets/plates.

Got a buddy that will let you borrow a reg for troubleshooting?

yea i got a buddy with one. so your saying that there is no way to know if its the alternator or the voltage regulator without having a good regulator to troubleshoot with? well what if i didn't have another regulator? i wouldn't want to spend money on an alternator if its just the regulator that's faulty

You can tell your altenator is good because you can test all the circuits (cap, pot, rectifier, stator/rotor, diodes, ect) what you cannot do (according to the TM SMR code) is de-pot the solid state reg to test/repair the circuits, and it would be news to me to find out the AGARS has this capability. To my knowledge the test for a reg is go, no-go, verified with a known good, and they are non repairable (PAFZZ, should be PAHZZ, but who assigns these codes anyways....). I bet I know a few jarheads who can fix them though

Use the known good reg to verify, chances are your reg is bad, these alts are very robust. I can pull up the 34 manual for the alt but you need to get me the NSN or pn# for the alt.

Can you replace?

albersondh said:

The reg is solid state and not a servicable part. In the shop we use a "known good" reg for testing. 200A are newer dual voltage inductive (brush-less) if Im remembering correctly. Do you get any charging off the 12v lug? Not much that can fail on those alts except bearings and rectifier sets/plates.

Got a buddy that will let you borrow a reg for troubleshooting?

Click to expand...

Can you replace the voltage regulator? If so, any chance you know the part number?

xtrememotives said:

Can you replace the voltage regulator? If so, any chance you know the part number?

Click to expand...

What is the NSN or pn# on the alternator? I can cross that to the NSN/pn# for the correct volt-reg.

Respectfully, please change the post title to something that describes your problem.

Don't lose the small spacers under your regulator when you pull the mounting screws out.