(I'm not sure this is the right sub-forum, please move if necessary)

I have been looking at some of the different things that you can learn from your car's computer and found it pretty interesting. What is not so interesting is paying $300+ for a reader computer.

I program computers for a living and was curious, is the interface to communicate with the car a public standard? I think I have read something about OBD, but am not sure if that is what I'm looking for or not.

If the documents were free, I could jimmy together an adapter and maybe try making one of these readers myself.

 

After doing some more poking around, I figured out that OBD-II is what I want. I looked in my car and saw where the OBD-II adapter is. Unfortunately, the OBD-II specification is not free, but is for sale at: E/E Diagnostic Test Modes

I'll leave the link in case anyone else is interested. It appears to be about $65.