2009 Volvo with Cummins 400 problem

I guess also, you could test for continuity if you know the ignition power supply pin #. And/ or test for voltage first, on that pin with the key in the on position, to check for 12v first. Then if that checks out to check resistance. Then check corrosion in/on wire. Then ecm.

there may even be pin to pin checks for the ecm too, to test it.

I don’t think Cummins QuickServe Online is still doing free 5 Vin accounts. If they are still free you can get your wiring diagram off that, and find the pin on the oem harness plug.