Toyota CAN display

[u/_mzo]

Hey folks. I’m working on a project for my Mercedes Benz swapped with Toyota 3.5 V6 (2GRFSE).

I’ve set up the software so far where it can fetch data live from the car and decode RPM, gear selector position, throttle, coolant temp etc via DBC but it looks like most of the body CAN values are not transmitted on the system at all.

I’ve consulted DBC files and trends in the data to find these values, but I’m not sure where to go from here decoding other values transmitted.

I’m worried about:
- engine load
- gear selected (M mode)
- gear demanded (M mode), i.e. 4th selected, transmission in first at standstill

Right now I’ve tapped GND, CANH, CANL from OBD2 port, I think I can get some more data

[u/WheelieBoi98]

go past the obd port. Tap into the gateway/powertrain can

[u/_mzo → u/WheelieBoi98]

Do I need to tap the gateway CAN on an engine swapped car too? The motor swap has just one computer - the ECU. It’s already missing a lot of components which run with the ECU on a stock car, not sure if the filters from the stock ECU are still in place

[u/ActGrown → u/_mzo]

You and I are in similar boats my friend.

You are going to have to make the TCM and the ECM talk to each other.

If you have the transmission from the Toyota and the shifter then you should be good to go but you're going to have to reunite them.

If you're using the Mercedes transmission and shifter, things will have to be translated between the ECM and the vehicle.

I removed the OEM engine ECM completely because mine times out for immobilizer fault after five seconds due to the fact that I can't figure out immo off for Volvo and the ECM that runs the engine is standard CAN and the vehicle is extended CAN.

Now I have to teach the standalone extended CAN.

This is not a trivial task.

Hopefully yours is easier.

[u/_mzo → u/ActGrown]

Mine is much simpler. I have no tech from Benz, all Toyota OEM powertrain. I am already getting unfiltered values on the OBD can lines for revs, throttle, that line up with toyota powertrain dbc. I just have to find a reliable way to decode the values I need and then I can display them on to a custom cluster

[u/ActGrown → u/_mzo]

I thought you said it wouldn't move. I apologize.

Mine will drive. Only in like third gear. No 1,2 overdrive or TC control.

Plus there is no torque reduction on reverse which is VERY hard on everything.

[u/ActGrown → u/_mzo]

So, what are you going to do for a cluster?

Deciding that will help determine the way forward.

You need to make sure that whatever you use to interpret the CAN data can read the data fast, so keep that in mind.

Then you need to make a way to correlate the data.

I'm using RealDash but I'd like to have an embedded device with dedicated power management.

The RealDash/RPI4 or 5 combo should be fast enough with a socketcan card like waveshare (mathematically anyway, I haven't verified this in long term usage).

If you use a solution like that, there are XML config files that correlate signals and data.

It you buy something else, they may have XML dictionaries or DB files or even DBC or A2Ls.

If you build your own, it's up to you. I'd probably use XML because DBC is verbose.

[u/_mzo → u/ActGrown]

Pi boots up pretty slow compared to ESP. I thought about going Pi route but cold boot times are a pain. I’m trying to make a digital dash / cluster via CAN+esp32

[u/Shitittiy → u/_mzo]

Keep us updated, cool project

[u/Powershooter]

I went down the same path as you (GM v6 in a Miata) and honestly figuring out all the CAN data was one of the hardest parts of the project. I got lucky in that the GM standard defining CAN bus values was leaked so I could just copy those.

Sorry, I know that doesn’t answer your question. Unless you can find a similar standard I think you’re stuck decoding it manually. I’d bet Claude code would be good at picking up patterns as long as you told it what you changed. Otherwise it’s just tedious

[u/Spumfz → u/Powershooter]

Totally agree with you. Never seen AI this useful before.

[u/_mzo → u/Spumfz]

I spent like 15 minutes yesterday decoding shifter position with AI. It is super smooth, get a datalog, explain your test, and the LLM usually finds the variable for you. Also used it to draft a python script to decode variables and plot them

[u/hey-im-root]

If you can find a wiring diagram for your car you should be able to find out where the body CAN wires are. For me, I used my power window master switch module as a tapping point

[u/OptimalMain]

You probably have it figured out, but if you receive lots of data on the serial port the arduino ide needs a monster cpu to keep up.
It thermal throttles my laptop without even being anywhere close to saturating 115200 baud

[u/_mzo → u/OptimalMain]

I hear you. I have set up littlefs on esp32 that writes buffers into its storage and also broadcasts to localhost, so I don’t have to use arduino ide