MoTeC Global Forum

Hello,
I would like to receive Wheel Speed and ABS data from GM vehicles directly through the OBD 2 port, and am struggling to figure out the best way of achieving this. I understand that most CAN data is proprietary and manufacturer specific, but I know people have been able to reverse engineer their way to getting the CAN ID's, but have had no success finding GM Specific PID's for wheel speed or ABS so far.

This will be getting set up on multiple GM vehicles from 2013-2018+, so I would like to avoid tapping into the vehicles CAN bus if at all possible, and would just like to connect through the OBD2 port.

I have the OBDII Service 01 Reply and Tx templates loading and functioning on my C185.

First, would it be possible to add wheel speed to the current templates compound message as long as I can determine the unique ID for each sensor? I would replace a few of the identifiers I am not using with these new identifiers.
ex:
010C = Engine Speed
01XX = Left Front Wheel Speed (Would need to reverse engineer the CAN ID for each wheel speed sensor)


If the above doesn't work. Would it be possible to set up a separate receive template using the Base Address for the specific module I'm requesting data from? I have found addresses for most of the GM modules. I would specifically be trying to do something like what is explained in the last post of this thread without having to directly connect to the vehicles CAN Bus.
(viewtopic.php?f=70&t=3903&p=17736&hilit=wheel+speed+obd+wheel+speed#p17736)

ex:
7E8 = Engine Control Module
643 = Electronic Brake Control Module - (Received Channels would be Wheel Speed FL, Wheel Speed FR, etc)

I have successfully adjusted a few of the received messages using this PID list (https://en.wikipedia.org/wiki/OBD-II_PIDs#CAN_(11-bit)_bus_format), but have had no success getting the wheel speed or ABS information. Any help would be greatly appreciated!

That data is available. It is a project to figure it out. Are you asking what tools you need, or how you go about doing it?

You could start with the MoTeC CAN Inspector program (download and installed the Utilities Installer):

https://www.motec.com.au/filedownload.p ... docid=3739

This will allow you to capture CAN messages when that bus is connected to an Color Dash logger. Now create a CAN template for the addresses you see being broadcast on the bus, and start decoding the channels you receive. Sometimes it will be obvious when a pair of bytes looks just like your GPS speed.

A quick google led me to this document that might be useful to you.

https://docs.google.com/spreadsheets/d/ ... i=1#gid=29

Good luck!

Thanks. That CAN inspector tool will be really useful; I'll start messing with that. That spreadsheet also has a lot of what I am looking for.

I guess I'm confused with both the tools and the setup.

Using CAN inspector with the dash connected to the OBD2 port, will I only receive data for what the transmit/receive template is already requesting?
Or are you saying that there would be additional received data from the ECU (or whatever module I have the Base Address for) that just isn't being received or decoded by the C185?

As far as going about creating a template for the broadcast addresses, I want to make sure I'm going about it correctly. I watched this video showing how to use the CAN inspector and have a few additional questions.
https://www.youtube.com/watch?v=HKVTVU0 ... 0and%20UTC).


From the screenshot, I'm not sure I understand how to translate the full CAN ID into something to be input into a CAN comms setup. Say you get a CAN ID of "00002001x" from the CAN inspector, how could this fit into a compound receive message? This is what I am picturing with the received message being displayed by a unitless channel, but I don't think the ID is correct:




I apologize for the poor explanations. I am relatively new to CAN and still trying to wrap my head around it.
Thanks for the help!

I think you need to get your MoTeC dealer to share with you DTN0019 (MoTeC Communications and Setup). This document contains a lot of useful CAN information necessary to create CAN templates.

The addresses 00002001x - 00002007x are 29-bit extended CAN IDs. So for that you would tick the "Extended" radio button under the CAN Settings/Address Format. Then you would enter 2001 (or 2002, 2003, etc for other messages) in the Base Address field. Those do not look like compound messages to me, so just check "single" in the Received Channels tab. Then you just need to add some channels, I would get either 1 or 2 bytes at a time, and initially use the "GP x (0 dps)" (x would be 1-60) channels as place holders until you determine what the actual value is, and how many digits of precision you will need).

Thanks.
I've got the CAN inspector running and will see if I can figure out some of the received channels.
I appreciate you calling out the DTN0019 document, I didn't know that doc existed since it wasn't supplied with the dash or listed on the Motec site.

Or I can just post it.