I've never worked on a vehicle with so many Gremlins.
Flashing using V8 2..2.258
Firmware 2.07.64
LS1B controller with OS #12606807
2006 GMC Sierra C1500Vortec Max with a small camshaft. I loaded the initial tune with some problems, had to try three times to get connection to PCM, and it drove decently well and no idle issues after the tune. After the tune I could log with no issues or comm problems. I then go to load a revised tune (same original OS) and at he end of the Cal flash I get a "Checksum failed" error. I'd never seen the error before and after looking all through the search threads I just turned the key off (truck had ignition on for over 30 minutes waiting for checksum retry or status message update).
Well I go to start the truck and PCM is in dead poll mode, no fuel pump, no cranking, nothing. I pull the PCM connectors, check all power and ground wires, as well as data wiring to OBDII port with no issues found. I had another PCM and hooked it up to the truck, truck cranked over but wouldn't start, b/c OS difference, with no issues (4.8 Van pcm). I then tried the PCM status and security runs on 2nd PCM, no issues, then I read from the 2nd PCM with no issues. So I go to full flash the original tune in the PCM and it goes all the way through the erase and write functions, then stops at "Checksum Failed" again. I left the ignition on for over an hour with no change after he error message. I had the truck on a charger, AC fuses and anything that might affect the tune transfer was unhooked/disabled. I then had to just turn the key off as the software would only let me either stop writing, or close the window. Now the 2nd PCM is in the same dead poll'esque state. I even tried the power and ground battery wires short for over 90 seconds to clear any BCM fault, with no outcome.
Any suggestions? Tune is attached also
Cliff notes "Checksum failed" message has resulted in 2 dead PCM's and 2 used licenses with no running vehicle. Truck won't even crank over with either PCM, but truck will crank with a spare PCM from another DBW vehicle. Then thinking it might be my V2, I read and wrote to an LS1B, E40, and E38 controller with no issues.