For anything not related to Speeduino, but still about car/bike/boat/engines etc
#56728
This is something new to me that I have never really thought about or attempted before. I know that I will need to have the speeduino talk to a few modules in my car, specifically the power steering ecu, if I want to go full standalone. My question is, how does one capture this data and figure out what modules are asking for what data.. then translate that to be used by the speeduino? I know the PS ecu looks for RPM and vehicle speed but I am not sure what else. For reference my car is a 2006 Toyota Yaris. It is a base model so it has no ABS and very few modules on the CAN bus to begin with. One thing I know the car uses the can bus for is vehicle speed.. the VSS connects to the cluster, the cluster interprets the VSS signal then sends that data via CAN to the ECU and im guessing the PS ecu also.

Any help would be greatly appreciated! Even if someone could just point me in the right direction :ugeek:
User avatar
By PSIG
#56740
There are a few here that are on-top of current CAN stuff. Off-topic, but my question (assuming this is a primarily racing app), is that the CAN input is primarily used to reduce steering assist at higher speeds, and linear assist without CAN (only switched signal, VBAT and GND). I assume you've tried linear and want the reduced assist feature? Disconnecting EPS CAN seems popular in some circles, but it's a personal preference of course.
By dazq
#56788
There is no magic way to get the info you are looking for I am afraid to say.
You will have to sniff the bus on the OEM setup and make recordings of the bus activity,noting specific id patterns that may appear .
Then slowly work through each id to note its relation to a function from the module that sent it .
Always keep notes of what systems were operating and under what conditions else you will end up getting lost .
You may well find id info on the net , many vehicles have been bus sniffed and a lot of data is out there, it is usually well scattered and needs cross checking but would help you get going .
If you do find the info you need, post it on something like GitHub for others to find in the future..
#56791
PSIG wrote: Fri Apr 29, 2022 9:44 pm There are a few here that are on-top of current CAN stuff. Off-topic, but my question (assuming this is a primarily racing app), is that the CAN input is primarily used to reduce steering assist at higher speeds, and linear assist without CAN (only switched signal, VBAT and GND). I assume you've tried linear and want the reduced assist feature? Disconnecting EPS CAN seems popular in some circles, but it's a personal preference of course.
My issue is that on my car if the EPS does not see the ECU talking to it, it does not provide assist. It wants to see, im guessing, an rpm signal before it will start working. If it never sees any information coming from the ecu it never turns on to provide assist. Currently the car is a street car, but the plan is to cage it over winter and set it up for road race use for next year.
#56802
PSIG wrote: Tue May 03, 2022 9:39 pm That is… odd. Oh well, good luck digging!
I could be wrong.. but the way the FSM describes it's function that is what I am assuming. I guess i wont fully know until i fire the car up for the first time full standalone
#56803
Log the data on the bus, see how many different IDs there are, if there is just one then you know the address. If there is more than one then try disconnecting the EPS, if the EPS is the slave then you would expect to see the master resend the data because it won't get an ack, that should then tell you what the EPS ID is.
Do you have a scan tool that can read the data from the EPS? if you have then you can set up a micro to replicate the data on the bus and see what the EPS is reading it as.
#56810
JHolland wrote: Wed May 04, 2022 5:48 pm Log the data on the bus, see how many different IDs there are, if there is just one then you know the address. If there is more than one then try disconnecting the EPS, if the EPS is the slave then you would expect to see the master resend the data because it won't get an ack, that should then tell you what the EPS ID is.
Do you have a scan tool that can read the data from the EPS? if you have then you can set up a micro to replicate the data on the bus and see what the EPS is reading it as.
Good idea! I do have a OBD2 dongle and torque pro with an extended toyota pid package. If I cant see it with that, I do have a usb mini vcm that I could prob use.

So i was looking back through the FSM yesterday and I am actually not sure I do need to do this. It looks like my VSS goes to the gauge cluster, then the cluster sends the VSS data over CAN. As long as the EPS does not need to see RPM from the ECU I may be able to get away without doing this. I will know soon, my parts to build my first 0.4.3 PCB should be here today :D

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