1.8 KiB
HOWTO Make Your Own ECU Communicate with TCU
What is this about
As of Feb 2024 it has been years since I've on and off started to work on getting an open source ECU to communicate with a transmission control unit via CANbus. So far I have not accomplished the goal which makes it a great point to write an article on the subject!
I have a 2006 Volkswagen Passat 2.0 Turbo GDI PG35 non-DSG automatic complete running and driving test mule idling on rusEFI open source ECU. Attempting to engage transmission while posting only minimal dashboard CANbus messages causes something violent to happen and the engine would usually stall see https://youtu.be/rTobt4l-iEs
Original ECU which I am looking to replace for no good reason is BOSCH MED9.1. Conveniently the relevant Bosch Funktionsrahmen Ea827 TSI is available on the internet. CANbus traffic seems to mostly align with https://github.com/commaai/opendbc/blob/master/vw_golf_mk4.dbc DBC file. I've used google translate to translate some of interesting field descriptions those are already merged into the file.
Toolset
I have PCAN USB dongle to record CANbus traces and a few Proteus units for Man-in-the-middle research. I've also created my own suite of CANbus trace processing utilities https://github.com/rusefi/can-log-tools/
First experiments
First let's grab a trace and a snapshot of CANbus traffic while engine is not running, both with OEM ECU and with OEM ECU disconnected. We get 722e81d2b0 (diff-457155f3530fe11dbca1083aa1860f4e3cccc8f2d8b78d81634def58fbc38d9f)
Comparing these two files we confirm which packets are clearly originating from the now disconnected OEM ECU 8575c7292d