dasickis

I was wondering what is the exact information you get from the ODB-II. Like what is all the information that it provides or does that depend on the manufacturer of the car? And what exactly can you do with the ODB-II port?

joeyoravec

The US government requires automakers to support emissions related functions on the OBD-II connector for all 1996 and newer vehicles, as described by SAE standard J1979. By law, the vehicle must let you:

• Read current powertrain data about 70 different sensors.
• Read "freeze frame" powertrain data that caused a trouble code.
• Read / Clear current emission-related trouble codes.
• Read pending emission-related trouble codes.
• Read oxygen sensor test results.
• Read test results for other monitored systems.
• Control emissions related system or test.
• Read vehicle info (vin, calids, etc).

A few years later, the government added a requirement that all 2004 and newer vehicles must support reflashing with SAE standard J2534. This way if there are any software bugs, they can be corrected in the field by a software update from the manufacturer.

Each automaker has hundreds (even thousands) of additional, proprietary parameters that are available from the OBD connector, beyond the EPA's requirements. It's often possible to diagnose or control devices. For example you can raise/lower the power windows, adjust the power mirrors, or detect button pushes on the radio on some cars. But this is proprietary and the exact process varies from automarker to automarker, and even vehicle to vehicle. Not all scantools are created alike; you would need a tool that understands the manufacturer proprietary commands to access the "really cool" features.

The short answer is: some things are standard across all 1996+ vehicles, others are unique to the automaker or even the vehicle. You can do it all with the OBD-II connector; it just depends what your vehicle supports and what your scantool or software knows how to do.

dasickis

Thanks this helped a lot!

For the full list of features available with the ODB-II do I just contact the manufacturer or do you know of any specific websites available to help me out? I have a 2004 Toyota Corolla, I'll try googling but if you have any good sites or places I could go.

Thanks again.

joeyoravec

The answer to your question depends on what you're trying to do.

If want a commercial off-the-shelf solution, you'll need to look at the features provided by the scantool you intend to buy. There are a lot of products out there; some good, and some bad. Make sure to check what the tool or software does for your 2004 Toyota Corolla, before making a decision.

If you're a programmer and want to develop your own custom software, you need to obtain the list of OBD-II messages and commands. Toyota is a large, busy company so they are unlikely to provide any support. For $50 you can get the list of government mandated messages in SAE J1979. For $7500 per year you can join the Equipment and Tool Institute, which maintains a library of data of proprietary and manufacturer-specific scantool info for its members. There are a lot of options, it all depends how much time and money you have.

And finally if you're looking for CarPC software, I've contacted the authors of RoadRunner, FrodoPlayer, CentraFuse, and Mobile Impact to offer free equipment and support if they add OBD-II support to their software. They're all interested, but these projects are usually driven by demand. If you're interested in OBD-II support for your favorite software, be sure to contact the author and let them know you're interested!!

Bugbyte

Here's a list of the generic parameters from Autotap's site.

Generic OBDII parameters

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dasickis

Thank you both for you support.
joeyoravec I am a programmer so I will like to pursue the options you listed.

Sorry for the short post, but right now I'm very sick and have just logged on to check email and all.

thank you again.

joeyoravec

FYI -- If you're a programmer, you may want to check out my company's new Mongoose vehicle network interface. Notice that it uses full-speed 12mbps USB, and we provide a full open-source interface to communicate with the vehicle.

If you're unfamiliar with the PassThru API (SAE J2534), I have a vehicle network programming tutorial available on the web. Our standard driver provides functions to: send / receive messages, send periodic messages, apply filters, and anything else you might want to do on the vehicle network.

I have three OBD-II controllers hooked up on the internet, so my customers can "test drive" our hardware remotely. Maybe this will help, if you want to see what it's like? For more info see www.drewtech.com. Good luck with your project.