My son left the battery charger on the truck at 40amps overnight. Its a 16 prostar with the cummins and automatic. Immediately after this, the def guage will not read properly, the dash says electrical fault, the truck starts but when you turn it off it continues to run for 10-15 seconds with the key out of the ignition before turning off. I checked all fuses and disconnected the batteries but no luck. Any ideas?