I just bought a 2002 3500 LB7, I have completely overhauled the fuel system to include new fuel lines from the cooler to the engine. I also installed a new water pump ,hoses, cam and crank pos. Sensors and a FICM from a previous truck I owned a few yrs back. I have no communication between the Ecm and my scanner. Also with the ECM (B) fuse blows as soon as you put it in like it's a direct short. I am having trouble figuring out what is all on that circuit. I haven't, found any bare or broken wires yet . Anybody ever encountered this before or got any ideals on trouble shooting?