Which engine do you have? What model? Are you not getting power to the ignition coil or no spark to the plugs?
If there is no power to the ignition coil I would check the cable from the battery to the ignition coil. I don't believe it is controlled by the PCM. I could be wrong but I don't think so. I would also check to see if there is a circuit breaker or fuse that has gone bad.