As I already mentioned, if a person unfamiliar with Bluetooth retrofit reads the first post of this thread it clearly states that all US-spec cars need to follow the TCU and FZD path: no exceptions. That person will have to read each post thereafter to potentially glean the nugget of information that E90's with the USB/Audio Interface may get away with simply adding custom-made wiring to get the mic working, but even then, it wasn't overtly apparent from someone already under the impression that a TCU and FZD are required components. The first post should definitely be modified to indicate there are other options. Actually, I was using a different thread from the exact same OP on these very same forums
that did NOT mention anything about E90's with built-in Bluetooth in pre-installed MULFs; it was only after the fact that I stumbled across this more detailed parallel thread.
And again, I already stated I already bought those components based on the first post; in fact, I already installed those components when I came across the non-working mic issue.
Since I didn't buy new modules so I didn't spend too much, and I'm not going to remove everything (it's a PITA to remove the non-folding backseat) and redo the MOST connections to original, I just want to get the mic working. What's done is done.
Those step-by-step instructions that I'm aware of only apply to taking the existing MULF and getting the mic to work, but I don't want to undo everything I've already done. What steps are needed to transfer the mic input from the MULF to the TCU? I've added $639 and removed $640 VO from CAS and NFRM but that did not resolve the mic issue.