Truck shut down at fuel pump

did you see if the fuse on top of the batteries is good, also see if you can swap relay 04 with some thing else.

 

Their is an ecm fuse on top of the battery boxes if I am not mistaken on a single red wire. Check to make sure that wire has good connection.

 

If your ECM is powered like a Cummins, then the power is sourced straight from the battery. Check from the battery to the ECM, there’s a break or major corrosion causing resistance.

If you knew the “pin-out” of the ECM, you could splice into the harness of the ECM. The wire that sends 12v power to the ECM. Cut about 6-12 inches down, add new wire straight to battery with a in-line fuse and maybe a switch.

Could also be, maybe it’s not getting the signal from the key switch ignition. A way to test this, is to unplug the starter relay on the outsides firewall and test for 12v power while cranking. That should be able to cancel out the ignition signal if testing good.

Good luck.

 

And or if that fuse has corroded from winter weather

 

problem is not ecm but vehicle ecu just back feed it for now you have a wire broken from batteries to the bulkhead connector i think it should be wire number 78 or 79 one of those that powers vehicle ecu try to read out the codes and see which one it will say operation failed on you should be able to read engine ecu and everything else but will not be able to read codes on vehicle ecu, try to back feed power for now to get moving from the maxi fuse for trailer abs should be only one there, it will get you home or around until you can make further diagnostics.