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.

 

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.

 

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.