M923A2 fuel shut off solenoid or protection or other control intervention??

[irontoys]

Just picked up a 1989 M923A2 with CUmmins 8.3 jumped it with slave cable and drove it without issue. Now on restart I notice fuel shut off was preventing restart. Removed that out of the equation and started fine. Noticed an audible alarm still on after air has built pressure, but no indicator lights. Suspect some control intervention that was/is energizing the fuel shut off, but I don't have a schematic or know all the possible interlocks that would cause the fuel shutoff to force shutoff. Oil pressure and all temps, air, etc. appear healthy. If anyone could explain all the interlocks it sure would help me troubleshoot it. Perhaps its just a bad shutoff solenoid, but that doesn't answer the mystery audible alarm. Thanks.

 

[juanprado]

That is the fail safe warning box/module with Buzzer. It get input from parking brake switch and low air pressure switches on primary and secondary air tanks.

Many threads on this annoying beast on the m939.