Good evening - just signed up today.
At the end of my rope with my Suburban, figured I'd come seek some guidance here.
Purchased this beauty in April. Bought with the understanding it had a GM reman tranny installed at 99k. I've since found out it has a second reman put in at 105k...has 131k now.
After a week of ownership the vehicle would not start. Brought to my mechanic and his computer showed the diagnostic below.

He changed fuel module, started right up. One week later, same thing. I bring it back, and it shows fuel module and ignition. He replaces fuel module under warranty and installs new ignition switch. Starts right up.
Few days later, same issue. Other little things happened in between like passenger window not working, and drivers side rear door lock not working. May or may not be related.
At this point I bring it to local dealership. They get similar codes, consult with GM tech support and go hunting for electrical. Check all fuses and boxes. Find corrosion on B2 terminal, clean that up and it starts.
2 days later, same issue. I bring it back and they pretty much tell me they don't know. So I bring it to another shop, whom I know the mechanic. He checks back up sensors (clean, no corrosion) fuse boxes again and cleaned up a couple grounds. Starts right up, now today it wouldn't start again.
My next option is to bring it to the dealership that did the transmission work (two hours away).
Are there any specifics I should ask them to check? BCM and ECM? Can they check those with the computer? I'm suspect of the internal wiring harness...?
Any guidance is appreciated. Thanks.