OBD Tutorial.

[DavidB]

Hi everyone.

I am looking for a nice tutorial on what i can do with this OBD port.

I think i speak on behalf of many when i ask for someone with experience using OBD (readers / adapters / cables) to please make a how to - low cost - obd code clearing and other usefull stuff relating to this topic.

pretty pretty please, with a cherry on top.

David

[06T200]

Hi David, im not sure what your question is? You just want a low cost way to clear trouble codes from the ODB port? Is it safe to assume you are using an ELM compatible device?? Anything can be done, so you might want to be a bit more specific as there are volumes of information to shuffle through. If you just want to clear codes using an ELM327 tool, you can open a terminal window (I use putty) and just enter in: 'ati' and it will tell you if the tool is connected, if it is it will reply back 'ELM327 v1.x', at that point you can type in '03' to read the codes (you will need to convert from hex), and enter in '04' to clear the codes. Doesn't get much lower cost than that.

More general info here: https://learn.sparkfun.com/tutorials...okup-guide/all

[DavidB]

Im not sure what ELM is, but i think i have a real question.

If i buy a OBDII to USB cable, can i plug it into my laptop and see live stats of whats going on with my sensors; see and clear any trouble codes, and potenially even unlock the firmware and upload my own.

I have some experience with the arduino platform, and some java and python programming.
One thing i would like to do is send my oxygen sensor information into an arduino and create the ability to adjust the readings on the other end. thus giving me the ability to change how the injectors behave to a small degree.

Attachment 10534

or am i crazy thinking this?

[06T200]

Yes you can, not crazy at all, in fact that is what the ODB data port is for. At the device level you can read info just using a terminal window on your PC, (will help you develop the arduino code) or most people like to use a software app to read codes, clear, read the PIDs (parameter ID's) and most of the O2 sensor data is in mode $05, most software has a good interface for this. The cable should come with some freeware OBD apps, but none will allow reflashing through the cable. That is a whole other animal, and differs depending on if pre 2008 or 2008 and later. 08 and later we can only read PID's by id and possibly by address, but no modes are really supported on the 08 and up stuff from my observation. I also use one of the small canned OBD gauges that is a bit more self contained for a heads up display in the car.

To write code for the arduino, there are several libraries currently for OBD messaging, and many of the PID message strings are setup in the libraries. Stanley the guy that runs freematics OBD stuff has written a ton of code for OBD data logging and has shields and LCD displays that are all arduino friendly. Some stuff is turn key, others you can just get the idea how to log data, and whatever your imagination brings. Fun stuff. I have one of Stanley's freematics OBD shields for a mega and it is pretty handy for logging sensor data and even deriving the fuel and ignition tables with a little math coding.

[06T200]

Here is a link to Stanley's shield I use, I just have the shield and a standard mega. He has a cable that will interface with our cars as we only use K-line (04-07) and CAN bus (08-11), but it is a bit more pricey than the generic ELM cables. He uses a 32-bit PIC controller to handle the protocols.

Freematics – OBD-II Telematics Advanced Kit (Arduino MEGA)


For flashing the ECU I have yet to source a cable/interface that has been tested and I am working on that at the moment. Right now your only option on 06-08 ECU's is to pull the flash chip off and read it in a Willem type reader with the amd chip adapter.

[DavidB]

That freematics kit is amazing. I am very impressed.
It is a little expensive to start with. I will get my hands on a OBDII to USB cable and see what fun i can have with that for now.

Thank you.