Yeah should have updated this earlier. I'll get back to updating this thread at some point.

It's more than just the crank signal, but here's your list of things that wont work.

VSC
Tach
Fuel quantity (not correctly at least)
Power steering

Airbag light will be on but airbags likely still work.

A lot of things work without ECU, including speedo.
If you want tach and power steering, just do what I did, spend $50 on an arduino with canbus. I tried to get ABS working but no luck. As above poster said; airbag light is on but might work? I never want to find out though.

Things I don't care that I'm missing:
TRAC (light is stuck ON)
Cruise Control
Airbag?? (light is stuck ON)
Accurate fuel gauge (still works but it's derpy)
Engine temp (I have a proper gauge)
Check engine light (mine is off permanently)

Things I care that I'm missing:
ABS and brake balancing systems (light is stuck ON)

Everything else works.

OK cool...
I don't care about abs, or traction.
I am going with a race dash more than likely.

Is it possible to control steering, throttle and brake via the CAN BUS?

For example, if I were to try to build a self-driving BRZ.

All I know is Honda stuff since I work as an engineer for them but

For throttle - you would need the proprietary CAN diag PIDs that control the FI ecu in order to control throttle. Maybe if you could find a toyota or subaru service tool and listen in on the bus as it talks to the FI it could make sense. The pedal itself is likely not a CAN based ECU, so you could not replicate it on CAN. The accelerator pedal position you see on the CAN bus is an output - broadcasted by the FI ecu.
We do not have an electronic brake booster so you could not control the brake pedal.
And, we do not have any ECUs that need to control the steering angle of the steering wheel, so you most likely won't be able to control it over CAN (for example if a car had an LKAS like system where ADAS-ECUs control the EPS you could hack steering wheel control).

Hi from the east!

Throttle is NOT CAN controlled. There are differential signal wires that go from the throttle pedal to the ECU. The ECU then broadcasts the position calculated by those differential signals.

You could possibly actuate the ABS via a CAN command, but that wouldn't be the nicest braking.

I bet the EPS could be commanded to turn. The newer Subarus with eyesight use the same message formats as the BRZ so at the worst you could replace the EPS unit with one from a different chassis that is programmed to work with Eyesight and go from there...

For sure you can't control throttle by trying to replicate the throttle pedal, but for example on Honda FI ECUs -
powertrain engineers can control throttle over CAN via a service tool or CANalyzer during development.

They can access the internal parameters through proprietary diagnostic PIDs and fiddle about. There's likely a similar way with Toyota, but of course, there's no way we'd ever figure it out without one of them blabbing.

I recognise this is a bit thread-dredgy but I'd like to see this initiative brought back to life.

I've created a GitHub project for an Arduino Due based CAN gateway. The idea being that those of us with development skill can contribute either in the form of decoding the bus messages, or helping optimise my (probably rather amateurish) codebase.

The hardware this is designed for is the CopperHillTech jcom.can.due.

Endgame would be to be able to opensource a CAN gateway that could be used to translate between any factory or aftermarket ECU and the BRZ/GT86/FRS CANBUS in a flawless manner. It's doable, but we need to work together.

https://github.com/wiretap/brz_cangateway

Canbus is just half the battle when it comes to interfacing with other ECUs. Even if you spend countless amount of hours and hundreds or thousands of dollars in hardware hunting down bit by bit on what every bit does. You still need to somehow handle the rest of the signals that dont go though can. And some people use the orignal ECU that their engine comes from. Some do,LS1 LS2, some LS3 other 2jz.. Some of those ECUs are not canbus. Some 2jz ecus dont even have OBD2 so getting data out would be hard.

So figuring out the FRS/BRZ/GT86 canbus is a good first step. But after that you need to first find what direction you want. Some like MRS-Colin have a gateway can network. But they do require to have the OEM fa20 ecu. Others like PureAutomotive have a all nice all in one solution. So for your second step you need to figure out how you plan to implement the bridge.

Definitely. I've got plenty of experience in those areas so I don't anticipate too many issues on that front. The hard part is that right now we barely have a starting point. My final objective is a device that will be flexible enough to allow a workaround for at the very least most common use cases, without needing any additional hardware beyond the device itself.

Yes I'm aware of other solutions out there, but this is different. Community-built and open source. Free code, Free hardware designs. I have nothing commercially to gain from this. If it motivates ECU vendors other than Motec to integrate something into their code, that is cool too! It's all about facilitating progress.

hmm do you have hardware yourself to get started? Thats very ambitious! IF you ever get stuck somewhere let me know. Il nudge you in the right direction.
Ive mapped like 95% of the Canbus network so il can give some advice when you need it.

Also take into account there are some hardware differences between the Push Start and Turn key cars that have to deal with the Immo system and also how its wires thought he ECU harness. And Again also some other IDs in Auto AC cars vs Manual AC.

If you're able can you contribute what you've decoded to the github repo? There's a list of interesting IDs at the top of the .ino file which relate to the canbus mailboxes in the ECU specifically that I'd really appreciate the help with.

The IMMO system from what I can tell in the push-button vehicles, which are the only type I have on hand at the moment, is basically all in the power control unit but feel free to correct me on that.

I've asked him technical details some time (10months) ago by email about the cluster canbus of our gt86 but he didn't wanted to share his knowledge ...

If you want some messages you could look at the code I've made here https://github.com/fontaromain/CANHelperLibrary

If I could be of any help :)

Hmm looked back on my emails and i cant find you. Most of my emails about that topic usually go two ways. If they need help with something simple im more than happy to help. But if they ask to have the code to get everything working perfectly then im hesitant because ive had someone try to make adapters and pass it as their own work. So those late nights i worked by butt off simply to have someone ask for everything then make there own left a bad taste in my mouth.

So what was it that you needed help on?

Also looked over your code. Is it mostly UIDs with OBD frames.

Again ive already shared my code with many people here in the forums too. Just a matter of what people's intentions are with it.