Hi all, please allow me to go straight to the point why I started this thread.
Today I spent almost a whole day trying to figure out why my Bluetooth after replacing a faulty MULF with a MULF2-HI doesn't work off the bat. The target of this thread is to let future people doing the same have another point of reference in research since I pretty much read all MULF replacement threads and could not solve the problem I faced.
My car, a Pre 03/2007 E93 335i was optioned with $644 (Bluetooth) from the factory so it has the MULF made by Visteon:
Unfortunately I guess Visteon didn't do a good job and the MULF died after 8 years. Symptoms of a dying MULF are music playback having a one second pause (MOST interruption?), Bluetooth not working intermittently (2 dashes above TEL in menu).
So after researching, I bought a second hand MULF2-HI from ebay:
The MULF2-HI, made by Harman (Becker), would probably have better reliability since even the currently latest NBT systems are also made by them so they must be doing something right.
So after modifying the connectors and doing the hardware swap, I was expecting to see Bluetooth work immediately but to my dismay, no, still 2 dashes. Pulled out ISTA/D, and it says telephone control unit not responding.
Pulled out NCS, checked 2RAD coding, no problem, everything is ok... tried to read MULF coding, error. Maybe it is true that it only takes coding through the MOST port. Moving on.
Disappointed, I did more reading and tried a few things with Tool32 like trying to run BT_AUS, STEUERGERAETE_RESET, trying to write VIN.
Nothing is working, either I get ERROR_ECU_CONDITIONS_NOT_CORRECT_OR_REQUEST_SEQUEN CE_ERROR or ERROR_ECU_SERVICE_NOT_SUPPORTED_IN_ACTIVE_DIAGNOST IC_MODE.
Ok, no go. So, moving on.
I then ran WinKFP to "update ZUSB" on the MULF2-HI. Both ZUSB numbers are the same (update and current) so I thought the flash would be 10 seconds tops while giving me my VIN AIF write.
Big mistake. It was taking 40 seconds for 1% and with my laptop having left with 20% battery, I'm really starting to panic.
Thankfully it made it through after around an hour that seemed like an eternity. Ran ISTA again, MOST reset. Still no Bluetooth.
By now I'm starting to give up and was consoling myself to use the MULF2-HI to retrofit $6FL (USB) instead. I had no intention from the beginning to retrofit USB since I would rather not bother with rerouting my AUX line to the MULF2. But now it's the only benefit that the MULF2-HI purchase can be salvaged from. Even though I don't have a USB FAKRA cable and USB port, I thought maybe I could code the USB options first. So I ran NCS again, added $6FL to the VO. Went in to see the modules list and... what.... MULF changed to 2MULF.
Tried to read 2MULF and it worked. Screened through the options in 2MULF trace file and saw the magic option "BT_EIN_AUS Nicht_Aktiv". Immediately I changed it to "AKTIV" and did an SG_CODIEREN. No errors. Changed to 2RAD, SG_Reset.
... BLUETOOTH IS BACK!!! But voice command doesn't work. Went back to the trace file and saw SVS_EIN_AUS_3. I remember SVS has something to do with voice command, so aktiv it and sg_reset 2rad again. And voice command is back!
Lesson learned - $6FL also refers to MULF2-HI.... so if you have a MULF2-HI, put $6FL into your VO!
So why am I so unlucky where other people that also bought MULF2s off ebay can just do a switch, plug and play and they get their BT back? It is because my donor vehicle was not optioned with bluetooth.... only $6FL and that's the reason why it had a MULF2-HI.
I hope this would help and save the time of the other people attempting the exact same thing.
PS: I even changed the fuses related to telephony to show how desperate I was.