1996 Jeep Cherokee code reader won't conect

Code say's no conection, could the cpm be bad, won't start. Started out with rough idle, than after that it won't start, had no fuel pressure, put in new fuel pump, found no power going to pump. Relays ok have power to them, then found I had no spark, replace with new cam sensor, still nothing, replaced with new crank sensor still no spark or power to fuel pump, jumped power to fuel pump found it would work ok. Just no spark or power to work things, code reader say's can't make conection. Can the cpm be bad, as that also runs the fuel pump stuff to, and controls the spark, and most every thing under the hood, also put in a new coil, im lost on it, hope you can help me on this. I am now looking at the cpm I just don't know what else to look for. Thanks Jim