These trucks can shut down or reset while driving. Please check the battery with MIN/MAX setting under load to ensure it's voltage doesn't drop below 30 volts under load. Static strap is still there, and, measure with ohmeter from strap to body for 10K resistance. Then check relay card under display for burned pins or fried relays. Remove the top cover and check all relay pins on card carefully. Second from left usually burns the female plugs. These relays should be changed if any weird codes appear as they are taxed heavily for electrical load and burn out. Hitting a bump will cause the ckt to open momentarily and the truck cuts out. If you see slight burned sockets, change the card. The EPO switch often failed on these, causing cut-out. The pins at the VM are often a source for intermittent codes. I would replace the relays if they are a few years old for sure...Raymond part 1-100-068
Lucky you only have one in your fleet!