Lmm will not start after re flash.

[lssleeper60]

Doing a dpf and egr delete on a lmm, after re flash truck will not restart (cal flash) with v8. V2 will communicate with ecm tried tech2 and no communication. Re flash with tis 2web and everything back to normal. Software is up to date. Any ideas or have run across this before. Thanks

[lssleeper60]

I did notice on v8 under calibration it's showing checksum invalid. Could this cause a concern?

[lssleeper60]

That was the problem, even after full reflash with tis 2 Web the checksum was invalid. Fixed with v8 checksum repair, re flashed and all is well.

[Scarface]

I had this issue on a 06 lly. I had to reflash it several times from gm tis2web for it to finally to accept a tune and run. come to find out the vehicle had used a predator for the 37 inch tires and it had corrupted that ecm. I did the programing from tis 2 web with the intent of it being a new ecm in the truck and that was enough to clear up the ecm to allow efi on it.