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hi everyone
i'm a newbie and i learning about modify hex cabli file.
i received the hex file of TCM of Chevrolet Captiva. i want modify it but i fail in checksum . in this file as i known, 2 first byte is checksum(C7F6), and (05 c2 61 f7) is file name. but I can't calculate checksum of file to C7F6. Please help me how i can calculate checksum of this file.
thank you very much

Hic, please help me, thank you very much

I'm not sure what that is, the captiva we have is a bit later model than your's & is a T76 trans module & the file size is 2MB your's is much smaller.... you really need to know more about what it's come from.

VX L67 Getrag wrote:I'm not sure what that is, the captiva we have is a bit later model than your's & is a T76 trans module & the file size is 2MB your's is much smaller.... you really need to know more about what it's come from.

hi, thank you for your answer
this file i took in GM website, and it use DPS(develoment program system) to up load it to TCM. All of file have 3 file and they in 1 zip file have 181 KB size. in 3 file, 1 file is utility file, 2 file is cabli file, i recognize 96625143 file is have paramater i wish modify. but i fail in checksum after i modify
nomarly BCM i can calculate checksum by use 16 bit big ediant checksum, and not it, after + 1. it will be correct with 2 first byte of file. but it not with TCM file.
Can you recoginze how to calculate this checksum. thank you very much
and this file is full zip file i can upload to car by DPS software

Its still VERY different to mine, these are the details for my TCM...

OS: 24265993
Calibration IDs: 24265993, 25191081, 25191080, 25191082
Calibration VNs: 0000B7F2, 00004BDB, 000019AC, 00003F0F

I've been looking at your files and looking at a few I have and they are so far different that I odn't think you have actual files.. I think they build a bin from those files? Might be better off reading the flash directly so you know what is there.. Or logging the sps session so you can see what is actually being sent??

btw.. In my files I don't see anything related to cruise control lower liimit if that's what your chasing after??

ironduke wrote:I've been looking at your files and looking at a few I have and they are so far different that I odn't think you have actual files.. I think they build a bin from those files? Might be better off reading the flash directly so you know what is there.. Or logging the sps session so you can see what is actually being sent??

btw.. In my files I don't see anything related to cruise control lower liimit if that's what your chasing after??

thank you, i will looking for more information

VX L67 Getrag wrote:Its still VERY different to mine, these are the details for my TCM...

OS: 24265993
Calibration IDs: 24265993, 25191081, 25191080, 25191082
Calibration VNs: 0000B7F2, 00004BDB, 000019AC, 00003F0F

thank you, i will find exactly what my TCM information

It sounds like its just the calibration segment of the TCM. Most aftermarket tools would read the whole file. It should be a standard sum of some type, the hard bit is figuring out where it starts and stops as well as the type of sum. There is text at the end of the file so it looks like the file is good - not byte swapped or anything.

antus wrote:It sounds like its just the calibration segment of the TCM. Most aftermarket tools would read the whole file. It should be a standard sum of some type, the hard bit is figuring out where it starts and stops as well as the type of sum. There is text at the end of the file so it looks like the file is good - not byte swapped or anything.

Yes it is
I have already recognized the calculation of the bcm file and the ecm file, but I don't know the tcm file. Do you have any ideas to recognize it (I used not but wrong result)
Thank you