After much digging I at least found the pinout in some Mercedes shop software.
But unsurprisingly the #startergenerator didn't send any messages on its own on the #CAN bus when hooked up to 12V.
It did draw 11 mA tho, so at least the pinout seems correct and the controller appears awake.
Trying to send some #CAN messages to the #startergenerator didn't prove successful either.
I'm not well versed in CAN, but the dongle just kept trying to send the single message on repeat.
So I guess it didn't receive a CAN ACK?
Afaik, all transceivers in a bus should ACK a frame, no matter if they're addressed or not.
Not sure why it didn't work. Maybe I was on the wrong baud rate or this device behaves weirdly and only sends ACKs after getting a magic message?
My first guess for missing ACK would be (like you) the CAN data rate is wrong. Or perhaps the bus termination is wrong, or there's an "enable" input hidden in the module pinout.
I don't know if this is helpful, but I wrote up a series about decoding a BMW gear selector last year. Like you, I had no CAN log - but had luck getting the diagnostics interface to hand over a few clues. https://www.projectgus.com/tag/bmw-f-series-gws.html
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