2007 International 9400i cummins isx

International is the only OEM that gets 12v+ for ECM from starter instead of battery posts. Remove all 12v wires from starter and check. I bet that you will find your problem.....

 

I lean toward Hulld and QUALITYTRUCK and will share a couple examples.
White GMC with a Cat: Ran over 400,000 miles and the driver complained about it cutting out at times. Just like you cut the key off but would come right back on. It was a 48 state truck but totally shut down 10 miles away. The engine would spin over with the starter. Test light light between the the frame and engine. No ground strap could be found between the engine and frame.
Pet with a Cat like Hulld said. Under a hundred thousand miles and had one loose cable on one battery. Driver was sitting in the A/C with the engine running. When it was driven the cable would make and break contact and the ECM would shut it down.
Freightliner had a lot of alternators and some starters put on in 150,000 miles. It had a bad ground connection between the cab and frame. All cab lights were dim at times and volt meter read low. Driver said the headlights were also dim at times.
I thank you are looking for something more like that.

 

You need to install a good load such as a sealed beam headlamp on your ECM power. Shake down the truck wiring until you get the light to flicker or the voltage to drop. Your freeze frame data will confirm the low voltage when the fault logs.

It has a bad connection, quit changing parts and go find it....

 

Any update on this? When you replaced the power and ground harness, did you replace the terminal pins in the connector at the ecm too?