2002 OS 12212156 .xdf

**babywag** · 11-19-2016

Originally Posted by dzidaV8

I'm sorry to hear that you bricked your PCMs, I tested only a few parameters on a real PCM, but the checksums appeared to calculate correctly. Please send the original and modified bins along with a change log to e-mail address that I sent you so I could see where the problem is.To be sure the checksums are correct before you flash, you can open the modified bin in free EFIlive tuner and check.

I also tried using these, just a VATS change results in an incorrect checksum.

**LRT** · 11-20-2016

Originally Posted by babywag

I also tried using these, just a VATS change results in an incorrect checksum.

There are 8 segments of code in the PCM, and 8 related Checksums that must be calculated. The 7 calibration segments have straight forward Checksum calculations.

The Operating System (OS) uses a unique Checksum calculation. It sums the entire areas before, and after, the 7 calibration segments (it skips over these), and also excludes the last 16 bit placeholder at the very end. The native Tunerpro Checksum plug-in can't properly calculate the OS Checksum.

There is an LS1 Checksum plug-in available for Tunerpro on the Delcohacking website that will calculate the OS Checksum, but it will only work with 512 Kb PCMs.

Attached below is a link.

https://pcmhacking.net/forums/viewtopic.php?f=3&t=3845

**LRT** · 11-20-2016

Can't seem to fix the spacing in the above post ... makes it a bit hard to read.

*** had to switch from the WYSISYG editor, to the standard editor ***

**babywag** · 11-20-2016

Originally Posted by LRT

There are 8 segments of code in the PCM, and 8 related Checksums that must be calculated. The 7 calibration segments have straight forward Checksum calculations. The Operating System (OS) uses a unique Checksum calculation. It sums the entire areas before, and after, the 7 calibration segments (it skips over these), and also excludes the last 16 bit placeholder at the very end. The native Tunerpro Checksum plug-in can't properly calculate the OS Checksum. There is an LS1 Checksum plug-in available for Tunerpro on the Delcohacking website that will calculate the OS Checksum, but it will only work with 512 Kb PCMs, and is accurate for most (but not all) operating systems. Attached below is a link. https://pcmhacking.net/forums/viewtopic.php?f=3&t=3845

Dimented's .xdf did correctly calculate (fix) the bad checksum for system section, even though it isn't correct for 12212156 os.
I don't have the plugin installed. I did not look @ the .xdf difference on how the checksum is calculated.

I played around some more and also got an incorrect checksum when trying to change some transmission items.
Right now as it is the .xdf(s) will likely brick the pcm if it is used.

**LRT** · 11-20-2016

Trying to use DIY tuning software is a little dangerous, unless you are an advanced user.

While I applaud the effort put forth by dzidaV8 in working on the XDF for the 12212156 OS, there are errors and omissions in the current draft version. There is no Checksum in the Transmission Calibration XDF. There is a Checksum in the Transmission Options XDF.

So depending on which of these you were using, that would explain one of the checksum issues that you experienced. The OS Checksum is very important to have in place. Sometimes a read or write will change the code ever so slightly, which requires that the checksum to be accurately recalculated.

**babywag** · 11-20-2016

Yep...I was just curious, it would be nice to have the ability to modify 12212156 os .bin files using TunerPro though.

EFILive shows incorrect on transmission calibration, and system after saving the .bin

Operating System 12212156 $EFCC
Engine Calibration 9358576 $1460
Engine Diagnostics 9358901 $B943
Transmission Calibration 9358310 $C4B6
Transmission Diagnostics 16264429 $B766
Fuel System 16264619 $6D0C
System 9373540 $8DF5
Speedometer 9362080 $D705

For the OP attached the original .bin, and the modified one.
Here is the unmodified checksum info in EFILive.

Operating System 12212156 $EFCC
Engine Calibration 9358576 $1466
Engine Diagnostics 9358901 $B943
Transmission Calibration 9358310 $C7B6
Transmission Diagnostics 16264429 $B766
Fuel System 16264619 $6D0C
System 9373540 $8EF4
Speedometer 9362080 $D705

And don't get me wrong, not bashing the OP or saying anything negative! Tremendous amount of work goes into .xdf files, and while they aren't 100%. Nicel that someone has put forth the effort!