So I've been working on my step brothers truck I'm no diesel mech but I am pretty handy with my tools .so he was driving and all of a sudden everything shut down wouldn't start so he gets towed home well then I scanned his truck it's a 2015 ecodiesal 3.0 and I get 4 codes one was the crank sensor which I changed which was no easy task put it all back together and still didn't change anything. Now I looked and looked for anything I could of over looked then had someone else scan it and they say the ecm isn't getting signal to replace the ecm and computer. Before I have my bro buy stuff he can't take back . Well I was thinking is there a way.to test the stuff before replacing something that may not even b the problem