N14 cummins no signal to # 3 injector plug before cross threw

OK
N14 Celect+
#3 cylinder dead
White wire has 1.06 volts with key on
Black wire 0 with key on
When running
White wire 0.1 or 0.0 volts (1,2,4,5,6 all act the same way)
Black wire 1.06 volts (1,2,4,5,6 all have 18volts when running)
Harness is 2 years old and pin 3/12 ohm out.
Trucks runs with a M11 ecm and #3 wire shows the same volts and 1-6 truck surges
Ran overhead
Sent ecm to get checked they say it shows no codes and worked on there truck.

Before all this truck would miss between 1500-1600 rpms. Atmospheric pressure sensor fault would show up once a day as intermittent. changed out 1# injector that cylinder was dead and fixed with new injector.

Sending ECM back today to recheck anyone ever had this problem

Truck will show same volts with test ecm on all plugs even 3 but not with the ecm that was in the truck.

Any ideas or do you think what I think that its the ecm? 3rd ecm in 5-6 years