CM870 ECM communication

[Rawze]

(09-12-2025 )Johnh62 Wrote:  ...Anyway I had our "expert" flash it to help out with that egr fault and he mentioned it failed almost thru flashing and now it won't communicate thru the OEM port again, \
...

- Your first post sounds more to me like someone not knowing what the heck they are doing, more-so than anything else.

CM870's are very different than more modern ECM's. trying to copy the program from one ecm to another.. heck .. trying to copy ANY program into it that is NOT a blank Incal file itself.. will make it to things like not communicate with the dash, and other quirky/screwy things. Even trying to edit a factory incal file (with the wrong version of CT) will corrupt it enough to make it act up. - It is well known about them.


Stop trying to put bad delete files into it and put it back to its original factory programming via Insite with the file that belongs to that engine ser#. After that, restore the work order/template in Insite so that it has all the dash settings etc.

If it still does not work correctly, then chock it up to the fact that some complete idiot purchased a NON-
OEM, USED ECM!!!. - and go get a new OEM ecm instead, and have the dealership pre-flash it completely with the programming it needs to run the truck and engine (according to the engine ser# and vin#).