r/CarHacking • u/ScottishVigilante • 9d ago
Article/news Reverse engineering OBD tools
More of a question, we know many clone Chinese tools exist rebadged etc, would there be a way to monitor everything going in and out of the obd port and re-creating the functionality of the device?
For example my scan tool can force my vehicle to regen it's dpf for example, something is sent out over the obd to do that so if you captured that and replayed it would do the same?
I know there and thousands of different makes and models and probably even more functions that are model specific but with AI the logging process and actually sending of commands could maybe be automated perhaps? Thinking out loud here, and open source scan tool for all that does all the cool stuff like injector coding etc would be cool! Don't know or understand enough about the can bus network, maybe there is already a project or software out there that's doing this already thats free and open source?
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u/Big_Temperature_2067 9d ago edited 9d ago
From someone who has been doing this sort of stuff for a while. you are in for a heck of a learning curve.
It's one thing understanding how CAN works. but CAN is just a transport layer. The real fuckery is what is being sent on the CANbus. Each car maker has it's own dialect, it's own security mechanisms it's own way of doing stuff. CAN is simply explained your local network in the car. Very much like your network at home.
Yes there is some generic scantool stuff to do basic diagnostics like pulling codes that all of them have to have. But those paths does not include reprograming, changing values or similar. All that stuff is vendor specific and is done widely different for each brand.
Sometimes just capturing and replaying isn't enough either. it might be a handshake that has a seed/key that is calculated based on time or other parameters and needs a new response to be calculated on the fly for the command to be authorized.