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Old 06-18-2008, 05:03 PM
Roncallo Roncallo is offline
Join Date: Oct 2004
Location: NC
Posts: 3,003
Originally Posted by Strife View Post
Well, the trick I see is not sending/receiving the messages ,but cracking what they mean. There is no standard for the application layer, and I'm certain that manufacturers make at least some kind of effort to encrypt it or to at least make it "fragile", meaning, that any goofing around will shutdown the system (go into limp home mode, for example).

It would take extensive "spying" and recording of an identical operational car, then analyzing, then copying the messages and programming them into a controller. and verifying that the messages do what they are supposed to do (which might be scary).

The controller part is actually pretty easy, there are 8051 based chips as well as PIC chips. Both have compilers, including BASIC compilers (!), cheap or free.
My feeling is that if I can get the bit stream into excel I will have it by the balls. MB does publish the bit stream pattern. I figure for example I could jack up the car turn the key on and rotates one wheel. In this case only the wheel speed sensor should be active on the CAN. Once the wheel speed tag is identified I can put it on the road to develop a wheel speed calibration. I don't need every CAN parameter, just the ones that talk to the transmission.
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