LS7 suddenly won't start...

[OKGMC4]

It's my brother in laws 64 vette. Car has ran and drove for months now, but the last time it was shut off it won't restart. Checked and no coil fire and with a noid light, no injector fire, but they have 12v. Computer seems to have 12v and the scan tool shows rpm while cranking so it would seem the crank sensor is working. It's like the ignition switch isn't giving the ecm the go ahead, but the all the wires on the switch are tight. Everything else including the fuel pump is trying. Any ideas?