Why KTAG/Kess checksums error and how to prevent it happens?

**Emily** · 20th October, 2019, 05:09 PM

When i read and write ecu by ktag, there is some problem checksums error eg. the units will not calculate checksums when loading files, i have found out the reason and prevent method, i hope i share here to help others.

The error above happens on both Chinese clone Ktag/kess and ECU clone ones. Why it happens?
According to the ECU, you must do a full read and then straight after that you must do a full write. After you've done that, teh ecu is open for you to load your tunes based on partial reads and writes. The reason for the full read and write is that it takes off the tuning protection on the ecu.

i did a full read a month ago, and only did a full write a week ago. Whenever i tried to write the tune file, the ecu would be bricked and come back with a checksum error after the write. So the secret is to do the write directly after the read. i did this with a FGTECH V54 but the process is the same for kess. i now write my custom tunes with kess to the ecu, and ksuite corrects the checksums for the partial writes. The process is different for other ecus i'd imagine.
p.s: i bought the ecu programmer-kess from eobdtool.co.uk e-shop

**Panathaole** · 21st October, 2019, 01:28 AM

If ecu is locked, ktag guide you for what to do when you read the ecu dump, so you can write it after by obd..., Usually all tools checking the modifications, what you have change in file and writes only the difference, not all the file...