I was driving down a 45 mph road and motor shuddered and quit running. Trying to get information had led me to rebuilding filter head and replacing all rubber hoses. Also replaced cp3. Cranks but no fire. I understand that FICM rarely goes out. Using a snap on scanner I am getting no codes. Very frustrated. Any ideas? Could it be as simple as replacing the batteries or is it the ecm? How can you test the FICM or the ECM? The truck was my daily driver and need it to get to work.