sorry to 'jack your thread but where the heck did you guys learn all this?! LOL
Everywhere. It's all over the 'net. The hardest part is figuring out where to start. I use OBDII every day at work but not at this level. I spent some time a few years ago trying to communicate with an OBDII pcm but I've forgotten most of what I learned. So I've spent the last few days looking through posts and threads reading this and that. And just like anyone else, I can get overwhelmed with the amount of information. If I see something I think might be useful later I download it and save it. The files Eaglemark just posted are a great example. I think I've got the same data in two or three different formats but I'm going to download it anyway. Sometimes I'll find a thread with a good discussion so I save the whole thing. Eventually I get to a point where I decide I want to "Do something" and I get to work. In my experience it's much easier to learn new info if you're trying to apply it at the same time as you're learning it.