What happened
As described in that other thread, I made a mistake when wiring the MMI box - due to the unfortunate combination of me not reading/requesting the installation manual beforehand and that the handbrake 10-pin plug is the same one as the alternate 10-pin iDrive plug, what I did on my first attempt to install the box was that I plugged its harness both into the 4-pin iDrive controller wiring but also the 10-pin plug (that should not have been used) into the handbrake plug. (Unsurprisingly?) the MMI box didn't boot, so I removed it and reassembled the dash. Only to later find out that my iDrive knob didn't work since then. To clarify, the iDrive system seems to work - the display works, my phone connects via bluetooth, I can make calls, PDC works, I can control the system using the pre-programmed memory buttons (1-8) on the radio - it's just the knob (and the other buttons on the controller) that's not responsive at all, nor does it light up.
Diagnostics / What I tried
I opened the centre console trim first to check for any obviously visible issues with the plug connection, or whether I clipped the cable during reassembly of the trim but didn't see anything. I even opened the 4-pin connector that goes into the knob, wiggled the cables, it all looked very much OK. My battery has been swapped for a new one in the meantime (I had a weak one during that 1st MMI installation attempt).
Now to determine whether the fault is in the controller itself or elsewhere (wiring - power, CAN bus, etc.)...
Having done some research, is this what each of the 4 pins should be? (Please correct me if I'm wrong.)
- ECCAAD07-6E1E-418D-BBBC-769007AB670E_1_201_a.JPG (188.72 KiB) Viewed 484 times
Failing to measure 12V makes me think that there's an issue outside of the controller. (While we can't rule out that the controller itself is broken as well.)
Any tips what to do? Should I try testing some fuses? (I found the fuse diagram, but have no idea which fuses might be related to this - which ones to look at.) Please help me fix my knob!
