"To get working buttons, you need to intercept the analog signal before it gets to the LIN node in the steering wheel."
"Working" in this context means "used for things other than the M1/M2 functionality", yes? Sounds like if someone wanted to map M1 to sport and M2 to sport+ or whatever, the steps are "buy and install the buttons" followed by "enable the buttons via FDL coding in E-sys"?
EDIT: Spent a half hour screwing around in E-Sys. Looks like FEM_BODY > 3140 PfLinSteeringWheel > LIN_VARIANTE_MFL > "DCC_Sports" should be set to "DCC_M_Drive" (or "SLD_DCC_M_Drive"). Would someone with an M2C and/or an M3/4 with the buttons installed mind taking a look at this setting and letting us know what it is?
As for the LEDs, if you post a picture of the existing circuit board I can probably get a part number. I assume they're just orange surface mount LEDs in 0402, 0603, or 0805 size, plus a resistor of some value in the same size. Since the other buttons are backlit, the parts should already be there.
EDIT 2: Some folks on the German 1 series forum have been asking the same questions we are (
https://www.1erforum.de/threads/mult...-m140i.260091/). They seem to be discussing it fairly actively and Google Translate in Chrome seems to do a decent enough job of getting the message across.