🛻2 very common things that happen when THE TRUCK WON'T START and IT WON'T COMMUNICATE Sometimes it's damaged wiring, bad batteries, or a blown fuse from your batteries to your ECM power supply. ✅ With a voltmeter, check the 12 volts coming from the battery and the ground from the battery too and make sure that you get at least 12 Volts between positive and negative at the ECM ( also try checking while cranking ) ✅Make sure that you also have your ignition 12 volts on pin B3. To see part number