Checksum error when trying to save.

Hi guys, I'm completely new at this, I've gotten to the point where I've used PCM Hammer to open my OS which is 12209203. When I go into Tunerpro, make a few adjustments, deleting VATS, setting the max speed to 200, and taking out P0420 &430, then try to save it gives me a checksum error. I'm not sure if those adjustments aren't allowed, I'm doing it wrong or what. This is just a test PCM I took out of a junkyard truck, I'm trying to successfully complete these steps before I look into my swapped truck. I did save each item in each block before trying to save the whole program.

What is the number in the name of the XDF file you are using to edit your OS? I'm not familiar with 12209203 and I don't believe there is an XDF for it but the two MUST be the same. If you edit the 12209203 OS with some other random XDF not made for 12209203 then yea, you just created yourself a checksum error.

I hope you still have a pristine undamaged copy of the OS somewhere safe. Or better yet, you are prepared to modify a different, more widely understood known OS BIN that does have a matched XDF file for the proper internal OS definitions.

Rick

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LRT, I just re-read the PDF file, I have downloaded the checksum file, I downloaded the XDF file from post 2 for 12209203. I think I'm following everything correctly. Just to take you through the steps I'm using
1. I'm connected through a bench harness to the PCM
2. I use PCM hammer to read the complete PCM and saved the BIN file, labeled as LS TEST PCM
3. I open TunerPro, open the XDF file, then open the BIN file.
4. At this point I only changed the VATS to #2
5. I try to save it and the check sum error pops up.

I'm sure if I'm missing something along the line. The pic shows the OS readAttachment 16600

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LRT, thank you for the help. My OBDXPRO arrived today, and I've been to do everything I wanted with a test PCM. I had been trying to use a Link LX dongle, but read on the LS Droid Facebook page the recent firmware was not cooperating for a lot of people. So I bought the dongle from Pete, deleted and reinstalled everything, and it works flawless. Thanks again.