What is this CAN bus?

My first attempt...

Which CAN bus am I connected to? Engine? Comfort? Connected in the Mazda RX-8, directly below the steering wheel at the OBDII diagnostic connector. 500kbit (all other baud rates cause the instrument cluster to blink erratically! )



From what I could tell, ID 215 seems to be related to either the speed or the airflow. When I pressed the accelerator, the values quickly increased, then briefly dropped to a lower value, and then returned to the initial value. It's probably not directly related to the speed, but the airflow would behave exactly like that.

How can I find the data more precisely? How do I determine the conversion factors? The whole thing is a bit like solving a puzzle with a blindfold on...

Actually, I would prefer the Comfort-CAN data. Window lifters, etc.

Greetings! Chris

Hi Chris,

If the data displayed in the image is all you're receiving, I would say it's the interior CAN bus (or also known as the Comfort CAN bus).

What speaks against it for me is the 500 kbit speed.
Normally, the internal CAN bus is slower (currently only 50 kbit/s in my case).

In my Stilo, there is also a lot of engine information displayed on the interior.
(RPM, airflow, speed, reverse gear, fuel consumption indicator... and many others that I haven't identified yet).

Do you have a button on the driver's side to control the passenger window?
Then, see if you can find the signal.
The steering wheel controls were also very simple to use.

Have fun searching.
Regards,
Peer.

Hi Peer!

It would be great if it were the Comfort-CAN!

When I press a button on the car, should a new line appear, or should an existing value change?

I've already tried many buttons. Things like the light switch, steering wheel buttons, brake, handbrake, etc., but I haven't been able to identify any clear changes yet.

Is the instrument cluster typically accessed via the engine CAN bus or the comfort CAN bus? (The instrument cluster malfunctioned due to an incorrect bitrate...)

Greetings!
Chris.

'Oh oh... After observing the CAN data stream for a few seconds, the MIL (Malfunction Indicator Lamp) came on. Even restarting the car didn't fix it. I had to reset the error code using an OBDII scanner.'

It looks very much like a Motor-CAN system, as no key codes are being sent. At least, I can't find any .

'The motor CAN bus would typically operate at 500 kbit. And it wouldn't be unusual for the instrument cluster to be connected to it, would it?'

Greetings! Chris

How can I find out which cables are for the Comfort-CAN on the radio? Hmm... Is there perhaps an easier place to access it? Theoretically, the Comfort-CAN should be present on all buttons, including the steering wheel buttons, right?

How are the individual buttons connected to the CAN bus? I think the seat heater switches are probably just direct power switches. And the sunroof switch isn't connected to the CAN bus either, right?
It would be great if I could use the 4-way mirror adjustment button for the CarPC!

Greetings! Chris

Hi Chris,
Please check the following file.
<!-- m --><a class='postlink' href='http://www.audiotechnik-dietz.de/pdf_technik/61006,61007,61009,61010,61300,61301anl.pdf'>http://www.audiotechnik-dietz.de/pdf_te ... 301anl.pdf</a><!-- m -->

While this only mentions the Mazda 2, it might still be helpful to you.
Regards,
Peer.

Cool! It's also described as the Mazda 6! It's quite similar to the RX-8.

'Okay, but exactly where is 'behind the instrument cluster'? Removing the speedometer and other instruments isn't possible without special tools. I'll have to use a flashlight to search for that white connector.'

Sure!

Best regards, Chris.

Hello Perfect,

A single button doesn't connect directly to the CAN bus; it needs to be integrated via a controller. For example, consider the window lift button: In many vehicles, the window lift is controlled via the LIN bus (Local Interconnect Network). When the switch is pressed, the controller for the switch sends a signal to the LIN master, which then relays it to the window lift controller. The CAN-Comfort system remains unaffected. However, in some manufacturers' designs, if the vehicle is locked with the remote control while the windows are open, the windows automatically close. The sequence is as follows: Remote control module --> Controller module for the remote control --> CAN-Comfort --> Gateway --> LIN master --> Window lift controller.
Result: Closing the window once results in a different ID!!!
I strongly advise everyone against sending any commands to the motor-CAN bus! It's frankly baffling to me that so many people are messing around with the bus without having even basic knowledge! If you need more detailed information, please feel free to contact me before you potentially damage your cars! It's not *that* bad, but judging by some posts (even in other forums), many people seem to think, 'I'll just plug something in and see what happens.' It's not that simple!

And to avoid any misunderstandings: I'm not a 'troublemaker' like many people of my kind are often called! I simply work a lot with the CAN-BUS due to my profession.

Okay, and after this lecture, I still wish you all the best, and...

Basti.

PS: For information, sebastian.spiegl@kfz-netzwerke.de.

Hi Basti!

Yes, I'd rather not mess around with the motor CAN! However, I'm still looking for the Comfort CAN .

As it appears from the workshop manual, there is only one CAN bus in the RX-8, and that was the one I saw at the OBDII connector (500kbit, engine CAN). Could that be correct?

For engine data, I still have the OBDII module.

Greetings! Chris