M998 with 200 amp alt running in the red

[jmenende]

Im worried about overcharging the batteries right now its running at 28vdc idle and 34vdc full revvs. I know analog gauges cannot be trusted but i verified these reading with my digital mm. Anyone seen this issue before? Can the 200 amp generators exitation be lowered a bit?

 

[Mogman]

1st make sure you are seeing the high voltage at the IGN terminal on the regulator, that is what the regulator uses as a voltage reference, if for some reason it is "low" then the alt keeps cranking up the volts to try to compensate.
Other than that you likely have a bad regulator.
Edit, there is no adjustment on the 200A regulator.

 

[NDT]

I might add you need to park the truck until that is resolved, bulbs and start box will blow.

 

[jmenende]

I might add you need to park the truck until that is resolved, bulbs and start box will blow.

Yes, its grounded. What should the ign terminal read? Thanks

 

[Mogman]

Yes, its grounded. What should the ign terminal read? Thanks

It should read the same voltage as the batteries or real close anyway, if you are seeing 34V on the IGN terminal then the reg is likely bad.

 

[jmenende]

It should read the same voltage as the batteries or real close anyway, if you are seeing 34V on the IGN terminal then the reg is likely bad.

Is the regulator repairable?

 

[TOBASH]

Is the regulator repairable?

No. It is “potted” meaning covered in epoxy and such.

I would like it, as I’m beginning work on replacing the expensive unit with cheaper components, just like when I worked with others and I posted when I took apart PCB/EESS boxes and published how to bypass.

How to bypass PCB? I am aware some HMMWV owners have done it.

I'm not trying to speak sacrilege here, and I don't want to precipitate a war of words. :shock: How might I build a manual control box? My 24Volt Landcruiser just uses a glow wire to show glow plugs are ready, and then she just starts right up with the twist of a key. Civilian 6.2 Diesel...

www.steelsoldiers.com

 

[juanprado]

If you have wet cell batteries, pop the caps and check fluid levels. Batteries could be boiling over needing acid/distilled water mix. There is a simple ball float hydrometer tool to check acid water mix.

 

[Coug]

Here is a link to the manufacturer's troubleshooting chart for the 200 amp system.
95%+ of the time when output is wrong, it's the regulator, but still a good idea to follow the test procedures.

https://www.ceniehoff.com/Documents/Ctrl_Hyperlink/TG17_uid252021123202.pdf