2003 Suburban No Start - Electrical???

[Rivas]

Hello All! I am new to this forum and first time poster. I have a 2003 Suburban 5.3l no aftermarket anything. I am trying to figure out exactly what is going on with my burb. Story: I ran errands all morning last week and got home around noon. I parked it in reverse in the driveway. I jumped in it around 7pm that same day. Cranked it up and it ran for about two seconds then shut off. Tried desperately to start it and nothing happened. No turning over of the engine. All I hear is the sound in the throttle body and maybe some clicking of the relays coming from underneath the hood. I tried to jump start it, but nothing. So, basically, when I turn the key nothing happens.
What I have checked so far:

1. Battery tested and checked out ok. (Autozone)
2. Checked all the fuses under hood and inside fuse panel. All are good.
3. Hooked up my scan tool, but now it says it cannot communicate with vehicle.
4. Inspected and removed the ground wire (black/yellow) from the rear of engine (passenger side) and grounded it with the main braided ground wire on the firewall.
5. Swapped out relays under hood. (Starter)
6. Tested current coming to starter solenoid 12v. Good.
7. Tested S at solenoid (when key is turned to start vehicle). No power.
8. Hooked up remote starter switch from S at solenoid to battery positive. Turned the key to run and hit the switch. Turned over, but no start.
9. Checked power going to neutral safety switch with test light. Yellow and Red wires (connector side) turn the test light on when ignition is turned to ON.
10. Replaced neutral safety switch. Same problem… no crank.

I am not sure what to check next? PCM? Is there a fuse somewhere I may be overlooking? I thought perhaps the solenoid may be shot, but I should still get power going down the S stud when I turn the key to ON, correct? Also, I don’t know if the passlock theft system is preventing it from turning over? I don’t hear the fuel pump kick on when I turn the key. Also, the chime sometimes stays on when I remove the key from the ignition. This is not an intermittent problem; it simply has not turned back on. If anyone has any ideas I welcome them! This thing is driving me nuts!

Rivas