hoping to get some insight on a issue that we're having with a couple of our buses.
2013 Blue Bird school bus CNG
engine will crank but wont start, dash will display the message: ENGINE COMM and BATTERY FAILURE. previously it only happened early in the morning when the temp was low, once it got warmer the message would go away and engine would start.. I'm leaning more towards perhaps a relay(s) for the ECM?
because of this message we're unable to connect to the laptop.
We didn't have this exact issue, but something similar. There are relays behind the left front door. You'll see a silver knob that you can stick a flat head screwdriver in. Give that knob 1/4 turn and that panel will lift out.