checksum?

[DDurfey]

Well my check engine light came on the other day with a code p1740 again but truck seemed to be running fine. I drove around for two days, code never cleared, so I cleared the code. I needed to have my front left ujoint changed before leaving for a camping trip so I figured I better make an appointment and have it looked at related to the code also. Dealer runs diagnostics and calls me that theres a checksum error and theyre going to reflash the ecm. Was on the job so I couldnt talk much so now i'm wondering what in the heck does checksum mean. Searched it and seem to get a lot of different responses. And......I had my tuner downloaded at the time. Are they going to reflash it stock and my tuner not work unless reset? Tuners a diablo predator sport u1730.

[GreyTD]

They got a check sum error because of your tuner. You need to unload your tuner before they reflash your ECM or you may get more problems. Checksum error is when a program has a certain count to add up to/meet, "checksum", if the count does not match then you get checksum error, meaning there is a problem with the program. Checksum is actually calculated within the program. Its one way to make sure the program is intact.

[DDurfey]

Called dealer first thing this morning and they had not flashed my ECM yet. I told them about the tuner and they said I need to unload it and drive it around for a few days to re register everything. Then they can rescan it.