Truck Died while driving, won't crank or start - Need help!

[Chuck&Truck]

Truck died while driving, won't crank or start - Need help!
My 2007 Colorado (manual, 105,000 miles) died while driving at 50 MPH. Engine died, dash lights come on as if key was turned to on from run.

I shut everything down, turned ignition to accessory, all lights came up normally. Turned to start and everything electrical is pulled down. I checked and re-seated the battery connections. I could find no blown fuses. Took battery in for testing and the tester was broke so they replaced with new battery since it was in free-replacement period.

Tried with new battery and same result. No solenoid click, all dash lights come on normally, no alerts or warnings. Turn key to start and everything goes black. Release key and all lights and accessories return to normal.

Passlock has been disabled when PCM was tuned 8 years ago. The only alert is a TPM light for a TPM sensor whose battery died 2 months ago.

I could sure use some good suggestions!

[Chuck&Truck]

Solved!   -  My truck was sitting outside the auto shop having baffled a half dozen "GM trained" mechanics for the last few days.  I used the circuit diagram and I first eliminated suspected grounding issues by measuring positive to left body and positive to engine.  Both measured 12.6 volts. I then walked through the circuit with my VOM starting with the Run, Crank relay activation voltage.  That was good, but when I moved to the next relay I had nothing.  I went back and swapped the rear defogger relay with the run, crank relay.  I found voltage on the next downstream relay.  The engine cranked, started and appears to be fixed.