OBD Interface ('95)

[TwoForties]

Ok Guys.. this is a tough one. I have searched extensively and have been unable to find any info... Here's what's up.

For my senior design project in computer engineering, I am interfacing a new Compaq iPac with my car's ECU through the OBD port. I already have a board built from directions on the internet to plug into the OBD port on one side and a serial port on the other.

I know that communication is achieved by writing to registers in the ECU and waiting for the control signal to be echoed back followed by the requested information. But I need to know more... much more.

Has anyone out there ever done anything like this? I have ordered a book from SAE which describes the OBD-II interface (even though I am pretty sure I'm OBD-I, my partners in the project are both OBD-II).

Anyways... if anyone knows anything about this or has any links they could send me it would be a real life-saver.

Thanks in advance for all the help

- Dave'95 SX

[SILVIA-S14]

95 is OBD I

That is all i can help with

I have seen people run EYEOPENERS

RINKU

[TwoForties]

The website where I got the hardware schematics is:

http://www.planetfall.com/~jeff/obdii/

- Dave

[Nismo_Freak]

OBDII is quite a bit different than OBDI. Good luck with this one

[TwoForties]

No, I am not positive it is compatible... and I have not found any evidence one way or the other. Except that when connected to VAG software designed for OBD-II use with Audi's/VW's there was some successful communication....

I.E. The VAG software transmitted a 0x08 (00001000) to the ECU and the ECU responded by echoing the 0x08 back to the software, which is how communication with a VW/Audi normally begins... after that, however, no more usful information could be obtained.

I am assuming that the communication protocols for the Audi and my 240 are very different... but the fact that my ECU responded at all gives hope....

- Dave