Not starting

Looking through our service manual it appears that the BCM should show up on a trouble code test. However, as you will see in attached instructions it may not be complete unless a special factory trouble code reader is used in conjunction. You may also have a problem with the Powertrain Control Module which I gave you a test instructions for. The referneces for trouble codes will come up on a reader unless a factory one is required and symptoms do not list anything about performance it just refers to other tests.
I think there is another possiblity. There is a crach module that is extra sensitivve and it may be intermitantly turning relays on and off as a safety percaution as it thinks it has been in a wreck. This particularlly includes the fuel pump. You may also be hearing the stater solenoid clicking and perhaps the battery ihas a dead cell. Check the voltage when you try to start it. Of course it should be 12V at stand still but should not drop when trying to start.
There was one other thing that can mess up a BCM or PCM, a battery short. It only leads to more round robin test instrucitons when I followed the symptom and gave me no goood information without having a factory tester. You may have done this or have shorted it or had a voltage surge of 5V which will mess up a BSM or PCM.
I also attached the BCM wiring diagram so you can see if any of the wires are loose or sorroded. Check the grounds for a clean metal to metal fit.

It al depends on the motor you have so I sent you the location chart.