Checksum error

When I read my PCM I got a "checksum error" on engine operation and I thought it might have had something to do with the modified tune that was in the truck at the time but when I finally got it to take a reflash and re read it it still showed a checksum error on engine operation but the tune was changed?? Any ideas?? I dont even know what a "checksum is"

This is on a 2006 LBZ 4x4 allison

ok, so the truck has been tuned before right, well, some programmers don't update the checksum numbers. The checksums are just used by the ECM as a 'check' that the data in the flash memory is valid. The LBZ ECM does not seem to be too worried about this though which is odd, in the past as an example, an LS1 with electronic throttle, if the checksum was wrong then the engine would not even run! ever again!.

It can be corrected in EFILive, there is a button just above all the checksum values called "Update Checksums", click that, resave / reflash the file and the warning will stop.

Cheers,
Ross

THANKS ROSS!!:cheers: