I recently bought a 3KW military diesel generator - and it needs a little help.

The generator is equipped with a Fault Module that monitors Oil Pressure, Temperature, Electric Load and Fuel level.

The Fault Module in this generator was unhooked when I bought the generator, and when I tested the module per the Instruction Manual, it did not pass several of the tests.

When I opened it up I found that this device has failed - it has come apart and is likely the cause of the malfunction.....the circuit board has no other visual indication of problems.

What is this device?  Is it a small switch, a transistor - or something else.  I don't see any numbers that would help me to order a new one.

There are 5 of these on the circuit board and this is the only one that has failed - the others have a semicircular plastic coating on the side that is exposed/burned on this one.  

     

MMRanch wrote on 12/02/25 at 13:56:51:


This generator is a DC generator using a solid magnetic core and wiring for the field coils.  The DC power is then converted to AC in an inverter unit.

The Fault Module is not a voltage regulator.....it is a specific unit that monitors things that are important to the proper function of the generator.  If any of the things it watches are not proper - the Fault Module shuts the generator down and displays the reason it was shut down by turning on an indicator light.  There is a "BATTLE SHORT" switch that can bypass the Fault Module - in case you want the generator running and don't want it to turn off for any reason.

I bought a used Fault Module to replace this one - but if I could get this one working again by replacing that burned out device....that would be cool!

MMRanch wrote on 12/02/25 at 13:56:51:


If I don't know what it is.....I am not sure how to test it?

I suspect it is a switch of some form - so that when a fault is detected it turns on a warning light and shuts down the engine.

Wow 53 hours is almost New !  

You always figure things out Dave !  

Eegore wrote on 12/04/25 at 09:16:03:


Yep - that is me!!!!

I did buy a replacement used Fault Module from Kris Klopp and that should solve the problem with that device.  It would be nice however to be able to find another inoperable one cheap - I could hopefully remove the needed part from that board to replace the damaged one in my board.

I also bought the new Governor Controller from him - the one in this generator is acting up and the engine cannot keep a steady speed.  This evidently is also a common problem - thankfully there is an affordable solution.

It also appears the Frequency Controller is a problem in these and a lot of the ones up for sale on GovPlanet are missing this important component.  Kris Klopp makes the needed equipment to convert the MEP831A from a 3KW inverter to a 4.2KW generator.....that likely would be more appropriate for what my home needs during power outages.  I am not running sensitive electronic equipment - what I need is power to keep my fridge and freezer working....along with the pumps for the woodburner to bring hot water into the house.

I can, and will remove the wires added for remote operation...the harness is just zip tied to the original harness and they added a couple of holes in the cabinet to run the wires....I can work around that and get them plugged up.

Ruttly wrote on 12/04/25 at 12:48:48:


It doesn't need to be rewired - it just needs a few simple things done.

1)  The Governor Module is something that goes bad - a fellow makes a new electronic replacement that is far more reliable.  I bought that and it will arrive tomorrow - it is a plug and play.
https://www.ebay.com/itm/185983635884?_skw=mep831a&itmmeta=01KBNSEAMR2581SE1N...

2)  Yes I know exactly what that Fault Module monitors....it is shown on the panel.  I  bought a used replacement from the same fellow that makes the new Governor Control Module - he tested the replacement Fault Module and it is a good one.  Another plug and play - 4 screws and 1 wiring connector.  (I have attached a photograph that shows the Fault Module front/back when it is assembled - the face plate shows what it monitors.  The little device that is cooked is on the circuit board contained inside this device).

3)  The wiring harness that was installed for the remote operation was a source of confusion for me at first - as it was not shown in the wiring diagram for the unit - and the installation of that wiring harness removed two wires that supplied power to the Fault Module.  Now that I have discovered the disconnected wires it is a simple task to get them connected where they belong.  And....as folks have suggested, I might was well remove the wiring harness for the remote - the remote system is not something I will ever need (and I have no intention of ever trying to find the control box).  I could use the empty holes as a place to mount a plug for a battery tender.

  a solid magnetic core and wiring for the field coils.    

Hay isn't that like a BIG version of your Suzuki S-40 ALT.     Is it three phase like my old Honda 350  and  Savage/S-40 has  ?  Three yellow/white wires ?

Trying to better under stand how something works helps me understand what caused the problem .   I suspect we're all the same in this regard

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The schematic for the stator looks like this: