Isolated GM Canbus sniffing



I’m extremely new to this form and would like to say great work! I look forward to exploring the possibilities that the M2 can do. I do have a question that i hope someone can shed some light on. I’m interested in sniffing a certain module in my 2018 Colorado and would like to know the best possible route to do this. I’d like to use a M2 device either the UTD or UTH version but i would like to isolate the Can bus directly from the Module to eliminate the other traffic. Can i use a the 26-pin connector and wires to connect directly to the canbus wires coming out of the module?

The module in question is new to the truck and was never built with it, so my issue is getting the calibration firmware onto the module. One of my theories is to flash the module form another truck/VIn that was built with the module and then start sniffing it to find the Vin location and replace the Vin with my Vin. Very much like the what some users are trying to accomplish with the HMI Module. Any input would be appreciated.



What I did in my situation was tap directly into the CAN transceivers and hooked it up directly to the M2 processor CAN TX/RX pins. I was able to see what the module was sending out for traffic. You could technically use a EEPROM programmer to save/backup the calibrations or clear the vin for relearning. This is an Onstar module I was tinkering with.


That’s a thought, my problem is the Module is a sealed Chassis controller module. Tapping direct would be impossible. I would have to connect via the twisted pare Coming out of the Module. If you don’t mind, what EEPROM programmer did you use?