I have a 2002 chev auto 4x4 4.8l vortex the truck ran a started fine . The trobl e started after I put brake lines on it just won't start now and don't know why I have checked for fuel have 55 lbs on pressure gauge have spark have replaced the crank sensor checked for broken wires i.e. grounds check every fuse one by one checked the injeftor pulse which is gone the secuity system also fine and just recently replaced PCM Every thing and still no start oh also won't make connection from ob2 and reader but have power

This sounds to me like the Body Control Module (BCM) may have lost track of the key or the key being used hasn't been registered to the truck.
If the key is one that you've already used, it's more likely the BCM has failed.
If the BCM doesn't 'see' the key, it cuts off fuel enable to the ECM to prevent starting. Hands-on testing is the only way to verify that is the fault but if you say you make no connection with the OBDII then you may have a failed Engine Control Module (ECM). Again, hands-on diagnosis is the only way to verify either module is faulty.