2001 Freightliner FL 70 Service truck wont start

So I have a 2001 Freightliner FL 70 service truck. Serial # 1FVABSAK52HJ65268. It has a Cat 3126. Serial # 9SZ06948. It will turn over but will not start. Our laptop will not communicate with the ECU. With the key on, the message on the LED screen on the dash reads:


No Engine

SID 254

Fail 07


When I turn the key to start, the message reads:


No engine

ICU 140

ABS 136


I have changed fuel filters, HEUI pump, and swapped out ECUs with a like known running service truck. I have checked all fusses that I can find.


I've tested the Unswitched +battery pins 51 & 52, ignition key switch pin 70, & -battery pins 65 & 67 for voltage on vehicle harness to ECU. All checks out good.


I've cleaned about every ground and connection I can find.


I'm at a loss. Not sure what else to do.

 

Yes. I did that. there is power going to said pins.

 

I checked that also. And there are no leaks or corrosion.