It appears connector C2280A GN-RD wire exits the BCM hot at all times (as long as fuse 28 is in tact), goes to connector C250 at the ignition switch, returns back through connector C250 as the WH-OG wire with and returns power to the BCM connector C2280B hot, but only when the ignition is in the run position.
Not sure exactly why, but my guess is that this was to bypass the ignition switch. It appears that if you jumper those two wires with the truck running that you could remove the key and it would continue to run. Again, not sure the reason behind this.
It also appears that if you jumper GN-RD (pin 29 on C2280A) with VT-GN (pin 35 on C2280B) that the truck would go into ignition accessory mode and if you jumper GN-RD with BU-WH (pin 47 on C2280B) that the truck would start/crank. Anyone want to try this? I haven't looked into the PATS portion of the start/crank option.