i have a 97 chevy with a vortec 350/ auto and a bad ecm. i got a 98 chevy ecm from a truck that has basically all the same stuff as mine but there is no small middle plug on the top like mine but all the other plugs are the same. when i plug it in to my truck it cranks for 2 seconds and dies. is there any way to make this computer work with my truck? what does that smaller plug with only two wires do?