MEP-831A High Temp Alarm.

[captain]

I have a mep-831a that was a reset unit and I have done a lot of work on it to get it running. Eventually, it ran fine. I ran it at 3kw for about 4 hours and it ran did ok. All of a sudden now it shuts off instantly with a high temp alarm. What is odd is that before you start the unit the high temp alarm is in and there is no low oil pressure alarm. The test button lights up all fault lights. I understand that the high temp alarm is a NO switch. I unplugged the high temp switch and the fault is still there. I did my best to trace the circuit from the J7 anthenol pin 24 on the plug side out to the plug for the switch and back to TB4 #6. I see good continuity and no short-to-ground. Can the A2 malfunction group have failed internally and caused this? At this point, I am even second-guessing my self as to if it was the high temp or low oil pressure fault that was on at start-up when the unit was working. If anyone has any suggestions for me to try I will be going back out to the unit tomorrow. Maybe you guys can save me from having to cart it all the way home and back out again. I'm not sure where to go from here other than throw parts at it.

Thanks.

Update. It has been more than 3 minutes so now I'm forgetting what I tried to get the generator to run. With battle short on it will not even crank. At least I think I tried that!

 

[kloppk]

Normally the LOP light is on before you engage the starter.
The Fault Indicator will only display 1 Fault, not multiple ones. Electronically the first fault is senses is what it displays.
The fault indicators can go bad. I've repaired a few of them out of 831's and 802, 803's, 804's. Every time it was an SCR that was shorted.

It will not crank with Battle Short on.

Try this.
Unplug the Fault Monitor.
Start the engine.
Switch ON Battle Short.
Plug the Fault Monitor back in.
Measure the DC Voltage with respect to chassis ground on pin 8 on the back side of the plug to the Fault Monitor with it connected to the fault monitor.
If the DC Voltage there is 0 or close to zero then the problem is a bad Fault Monitor.
If the DC Voltage there is around 24 volts then there is something else wrong.

 

[captain]

Thank you. I will try all of that in the morning and report back.