Fredrick, hi!Have never used SD3, but I doubt would connect with Monaco. Better to use VAS5054, I personally use VXDiag Nano for Toyota.
Attached is WIS doc to help you out with the wiring.
I finally succeeded with audio 15 in w211
Just before NY i've found a nicely priced 2013 w906 unit, and instead of driving a car crazy, it locked up as it should have. Unfortunately it appeared to be from a stolen car, and it was impossible to generate an unlock code. Yet just today we changed it for another one (and asked for a serial number and purchased a code before), but it the end it appeared to be even already unlocked. It works fine. The only issue, is just as you've said, nor really anything is displayed on the dashboard. It just says Audio, not displaying track name/ radio frequency, and not telling whether it is in radio/BT/Card/Aux mode. Though i think i might be able to fix it later, i've found a manual explaining how the codes between AGW and IC work, and suspect it will mostly take a some king of a can decoder (like Canny 7.2) tuned to change one address bit and a check sum in some CAN messages. Will keep you posted. Anyway, steering wheel controls work totally fine and there are no errors in a car.
Thanks again for the idea!