ISX Cm871 cutting out (2025)

02-17-2025, (Subject: ISX Cm871 cutting out )

I have a 2008 kenworth T800 that I recently bought and it has the ISX Cummins in it. I’m having trouble with it cutting off when under acceleration. When it’s cold and you first start it up and start driving the rpm will not read over 1000rpm after it cuts off once while driving the rpm will read correctly and sometimes once it cuts off the next time it won’t read at all. I’ve tried the tap test on the ecm and it won’t cut off from being tapped on. And I found that one of the main 2 main power wires in the 4 pin connector doesn’t have power the grounds are good and the other wire has good power. I traced the wire back to a fuse just below the ecm and the fuse is good and the circuit reads good to there but I can’t find where the wire goes to from there.
I appreciate Andy help on the subject!

02-17-2025, (Subject: ISX Cm871 cutting out )

02-17-2025, (Subject: ISX Cm871 cutting out )

I’m trying to be to trace the wire down I’ve followed her to what looks like a relay on the side of the engine and it looks like a small white wire comes out of the relay

02-17-2025, (Subject: ISX Cm871 cutting out )

if you make an account at quickserve.com (it's free) you can register your ESN and get the wiring diagram for your engine. Also you can look up any parts and service information as well.

02-19-2025, (Subject: ISX Cm871 cutting out )

Ok I tracked my power problem down to blown fuse in the harness just above the valve cover at the firewall. But on the test drive it still cut out once. Is it possible to have a bad ecm and the tap test not show it?