OpenEuphoria

RE: OT

• Posted by Jonas Temple <jtemple at yhti.net> Aug 28, 2003
• 369 views

Funny you should mention this.  I've been doing some research on the 
same topic (for a while now).

I have a friend that is a mechanic and we've been looking into writing 
our own OBD-II Windows application.  I've gotten so far as downloading 
some technical specs from various web sites and even have 3 ECUs at 
home.

Basically, OBD-II is an automotive standard regulated by the federal 
government that says all cars produced 1996 or after must have an OBD-II 
compliant interface in the car.  OBD-II as a standard only dictates the 
data that must be available through the interface and the physical 
connection that must be present.  However, what the standard doesn't 
dictate is how the communication must be done and each of the big auto 
mfgs have their own.  In the USA you'll find 4 different flavors: ISO, 
PWM, VPW and Keyword 2000.

>From a programming standpoint you unfortunately can't just hook up the 
OBD-II cable to the car and plug it into the serial port on your laptop. 
 What you'll have to have is a piece of interface hardware.  You can 
either make them yourself or buy them from one of many sites.  I found 
one for $80 bucks that supports the 4 mentioned, but I haven't gotten 
one yet.

I also know that the complete OBD-II standard is available in document 
form but it's not free.  You'll need the SAE OBD-II reference guide to 
know how to interpret the information returned from the ECU.  I found it 
at Amazon for $140 USD.

If I had a lot of free time I would like to explore this and maybe come 
up with a Windows/Linux OBD-II Diagnostics application. That is, IF I 
had free time.

Here's some other sites that might help:
www.obddiagnostics.com - this is where I found the interface for $90.  
Also has a really good description of OBD-II and some free software 
available for donwload.
www.andywhittaker.com/ecu/obdii_software.htm - another good information 
site, he's also got an OBD-II ISO interface for sell (I tried to contact 
him, but he never returned my emails).
www.scantool.net - you can buy a combo package with ISO, VPW and PWM 
interfaces for $184

Be prepared, you could REALLY burn a lot of time on this!

Jonas Temple
1evan at sbcglobal.net wrote:
> 
> 
> Does anybody know where I can get specs on OBD-II?
> 
>