Hello all... I am really trying to get an understanding of the j1850 protocol but need help. When trying to request the trouble codes, a 3 byte header will be used. And, from what I understand, you are to use physical addressing (not functional). My question is, what goes in the second byte of the header? I thought the first data byte (after the 3 byte header), was the place to send e/e troubleshooting bytes.
TO help me get started, could someone send me an example of what my header and data field will look like when requesting trouble codes?