Cheksum of a SAAB IPC

European GM ECUs and PCMs
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Joined: Mon Dec 12, 2022 5:12 am

Cheksum of a SAAB IPC

Postby teknik@speedparts.se » Fri Dec 16, 2022 2:24 am

Hi,

Anyone can do chk for this ? search area en method of CHK
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12784999AA_1.rar
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Posts: 6
Joined: Mon Dec 12, 2022 5:12 am

Re: Cheksum of a SAAB IPC

Postby teknik@speedparts.se » Sat Dec 24, 2022 8:57 pm

Finally i get the CHK right! This probally just a part of file since it comes from TIS to web but that have dosen`t mather;-)
After i have cheked around all GM files actually have chk 0000 calculated over all data so normally you calculate chk by do big endian 16bit or litele endian 16 bit exept 2 first byte. Then you second complient on result and put in 2 first byte. How ever the checksum over all byte including 2 first is allways 0x0000. So in my case i only put 2 extra byte in my file compensate it so CHK over complete file is 0x0000 do my change and calculate chk over evrything exept 2 first byte do second compliente put the result in 2 first byte. chek so i have chk 0x0000 over complete file if it`s ok i remove my added byte;-) doubele check so i get same CHK over complete file that i hade in my file from tis to web and you have good chk.
Hope this help some other with CHK problems in GM ECU:s. I add file with my 2 compensate byte added.
Attachments
le_web_chk_12784999AA_1.rar
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