More than you ever wanted to know about the MULF2 High Basis BMW Module

Being out in LA, I recently bought a car – I ended up with a used BMW. It’s pretty sweet, but I’m me so obviously I’ve moded just about everything I can without actually buying parts. Mostly that means software mods – windows up on key fob lock press, that sort of thing. But I’ve also been trying to mod bluetooth into it, and only recently had success. Tonight I got curious and took the module which controls bluetooth and USB aux-in apart (referred to as a MULF2 High Basis, it lives in the trunk and connects to a USB plug in the center console). Here’s what I found.

MULF2 Bottom

TOP SIDE: Not much interesting, mostly glue logic.

MOST bus interface controller

LDO Regulator

Hex Schmidt Trigger (glue logic)

Octal buffer (glue logic)


PCI USB 2.0 Host Controller
This one’s interesting in that it’s a full-fledged host controller like you’d find in your PC – it advertises compatibility with built-in OS drivers in Linux and Windows. It suggests that the board is probably running some kind of embedded Linux, which makes lots of sense. Interestingly, it looks like the chip has both 2x USB1.0/1.1 controllers and a separate USB2.0 controller, with two transceivers (physical ports on the chip) for them to connect to. So you can be running 2x 1.1 ports or 1x 1.1 and 1×2.0, for example. If I had to guess, the controller is running 1 and 1, with the USB2.0 dedicated to the center console port, and the USB 1.1 going to the on-board bluetooth controller (see below).

Spartan XA3S500E
500k Gate Spartan 3E automotive FPGA
Not especially surprising – if I had to guess, they’re using it to implement a MOST PCI controller or something like that. Really, it could be anything or a bunch of things, though.

Renesas SH7780 (R8A7780)
400MHz 32-bit CPU with 32-bit PCI bus
This isn’t especially interesting. Just some generic RISC CPU. But it probably has the horsepower to run a stripped-down embedded linux. More likely, it’s actually not, though, it’s probably running a lighter-weight RTOS.

Definitely DRAM or SRAM of some kind (running memory for the CPU)
Unfortunately, I can’t find any info on size or anything. If it’s big DRAM, that probably means the board runs embedded linux. If it’s smaller, probably a more compact RTOS. Tough to say – the 512mbit flash is definitely program memory (the SH7780 has none), and 512Mbit (64MB) is big enough for a compact embedded linux.

It’s interesting, I’m not really sure what the unpopulated BGA (ball-grid array) below the flash would have been. It doesn’t look like a spot for another RAM or flash chip, which would have been pretty expected (use free space on your PCB to add more ram, then if the programmers can optomize the software enough, just stop populating one chip to save a couple bucks a unit).

BlueCore BC41B143A
Bluetooth 2.0+EDR USB 1.1 Slave
This chip runs the Bluetooth show. Basically, it’s a USB1.1 Bluetooth dongle plugged into the computer that runs on the rest of the board. Via software in the chip, you can choose to implement whatever profiles you want supported by the Bluetooth 2.0+EDR spec, including Handsfree (as they’ve done) and probably A2DP too (wonder why they haven’t?). It could be that the rest of the computer is too slow to handle A2DP, or that streaming the audio data from the chip requires a USB2.0 port (the only one of which I can only presume is occupied by the center console port). Curious either way why the hardware should theoretically support bluetooth streaming, but they’ve seemingly omitted the capability.

BONUS: I forgot to write the number of the chip on the top right. Initially I thought it might be an audio DAC, but maybe or maybe not. After USB and MOST, there are 6 wires going into the MULF – the big ones are pretty clearly +12V and electrical ground. That leaves 4. They could be l/r/ground/something, but I think not. I think they’re CAN-HI, CAN-LOW, CAN-V+ and CAN-GND for diagnostic/vehicle bus communication. Most people tend to think diagnostics for the MULF are over the MOST port, and there’s a MOST-CAN bridge somewhere in the dash, but I’d still bet anything those 4 are CAN for basic control (the vehicle is on, do your thing, etc).

If that’s true and no analog audio out happens in the MULF, I’m not sure why they didn’t simply implement A2DP. It’d have been easy enough. And now that I think of it, the chip is probably an audio ADC for microphone input, since that IS wired into the MULF. Maybe I’ll go pull mine apart again and probe it, now I’m curious.

49 thoughts on “More than you ever wanted to know about the MULF2 High Basis BMW Module

  1. Dear Alex, I´m having a problem with the MULF of my BMW 2006 325i. This MULF there is not USB port (MULF “1”). I bought another one but the car not recognized it. Probably its need to have the car data inside. Where is the data stored? Can I move the “chip” from one board to another and it will work? Tks in advance!

  2. You definitely can’t swap innards, but that shouldn’t be a problem anyway. When you say the car doesn’t recognize it, what do you mean? What features did you start with (bluetooth? you said you DIDN’T have USB…)? Have you coded the new features in to the CAS and FRM ($6FL for USB, $644 for bluetooth)?

  3. Alex, when the BMW dealer connected the computer in the car plug, it didn´t “see” the MULF that I bought. The computer recognized the old one and indicated a error but not the “original”. The dealer said it is happening because the MULF is coded with the VIN number or something. The original MULF controls BT, CD charger, PDC and the radio. My car doesn´t have USB option (I think MULF2 offers it). I started having problems with the BT, after that, the PDC started fails, in the end, everything stopped work. I noted that the commands started to have a 15s – 20s of delay. If I increased the volume, the radio responds 15s after I press the button. The radio turn off 15s after I close the car.
    No, I didn´t code anything. I just tried to exchange the unit.
    Tks for your attention.

  4. I’m unaware of the MULF requiring VIN coding, I’m pretty sure you can’t do it without the expensive bmw diagnostic suites dealerships have with the MOST connector, and I’m not sure how you’d do it. BUT, the first thing I would try, just for fun, is to add $6fl to the VO in FRM and CAS

  5. Hi Alex,

    I have been trying to install the Bluetooth and USB in my 1 Series 120d N47 engine for a while one. I have been able to do a custom power supply and bought he other cables (USB and Fakra). I have added VOs $620 (voice control), $644(Bluetooth) and $6FL (USB/AUX) to the CAS and FRM.

    After going to a garage where a mechanic is updating the whole car I can finally see the Bluetooth and USB/AUX option. But they are grey out.The AUX works as before.

    Now I am trying to troubleshoot to get them to work. It seems like I need to connect something else but I am not sure. Is it may be the Can-Low and Can-High to the M-ASK/CCC pin 9 and 11? Or may be the cradle on the central console? Or both?

    I have been trying for a while to find the MULF2 54 pinout schematic to sort this out. Can you pass me this info and may me help me out a bit?

    Thanks mate.

  6. I wish I knew more, but unfortunately I don’t think I can help. You definitely don’t NEED an eject box for this to work. The MULF itself has no pins for CAN, all it’s comms are over MOST.

  7. Hi Alex,

    I have a problem with my car / mulf2

    Just retrofitted into a e93 335i the mulf 2 using the harness that was existing in the car.
    I had the aux in jack before from the ccc unit, I unplugged it and connected it trough mulf2 so now I have an aux in working trough it. Bluetooth function works perfectly.
    I also coded the car for usb but the usb audio function is grayed out/ unselectable.

    I made my own harness using schemes from the internet with fakra plug into mulf and out to usb port, it charges my ipod but usb audio function is still grayed out / unselectable.

    I know the coding is alright to the car.

    I read on the mulf 2 pinouts that from the 54 pin plug from mulf2 I have to wire 2 pins to no. 36 and 17 and plug those into the USB HUB. Now, I don’t have a USB HUB and I know it s not necessary to have one as I only have one usb.

    I guess this is the problem, pins 36 and 17 which may lead to my usb input connector.

    Can you please tell me where may those pins 36 and 17 lead to into my diy usb plug? 5v+ and ground? Data + and – ? I CANNOT FIND ANY USB HUB PINOUT INFO 🙁

    Thanks alot!

  8. Dear Alex,
    I have a 2010 E61 with the CIC, voice control and bluetooth. Bluetooth started to give intermittendly problems (sometimes connected, sometimes not.) When not connected, I can not see my phones in the bluetooth menu. As of late, I never get a bluetooth connection.

    Is this something that can be repaired, or do I need to change the entire module?

    Peter (from The Netherlands).

  9. @john sorry, I really don’t know 🙁

    @Peter I’m not quite sure. It sounds dangerously like something on the board is going. First thing I’d try is deleting all the pairings from phone and head unit, then re-pairing, but I suspect you’ve probably done that. Next thing is to see if maybe you’ve got a loose antenna or other wiring somewhere, which seems highly unlikely. If it’s the antenna, I also wouldn’t expect complete loss of connection, just poor quality (choppiness and the like on a call). Failing that, I’d try the standby of unplugging the MULF totally for a while (pop the blue connector off), verify that nothing (USB, Bluetooth) works, then plug it back in maybe a day later and see if it clears up. Beyond that, putting my EE hat on, a likely culprit is bad power supply hardware in the MULF, but that’s hard to diagnose and probably even harder to fix (maybe you’ve got a bad cap somewhere, maybe a regulator is dying) – that’s the point at which a dealer would simply try swapping out the module to see if the issue goes away.

    Here’s a question: does USB work reliably?

  10. Hi Alex…

    I dont know if you still use this, but I stumbled upon your page..
    Im in ireland and have a E60 520D M-sport BMW.

    I only have the car a while, and water got into the boot area, and caused trouble/corrosion in my PDC and Bluetooth box.

    The Bluetooth module i have is a High Basis SVS part no 84109200822-01 there is only slight damage to the board by the looks of it… I was wondering if this exact part has to be used as a replacment part of if there is another part that can be used..?
    Thanks. kindest regards; Stephen.

  11. You can buy a MULF2 from ebay or something, though it MAY require going to the dealer to have the unit paired to your car’s VIN.

    Depending on how cheaply you can find a replacement unit, it may be attractive to look into either a Mobridge MOST bluetooth retrofit module or a Dension Gateway 500 (maybe they have newer models now, but same deal). Both are effectively designed to replace the MULF, but with a better feature set like iPod/iPhone integration over standard USB (no Y cable necessary) and A2DP bluetooth audio streaming.

  12. Hi Alex
    I have a mulf2 high has been broken a componet (a75240) Might tell me where I can find it, or if the house that makes the plaque would sell me or a new plate, and you can give complete reference on my plate is not read latuya and I can only see the chip numbering is a 4-pin x2 encribes to email me if I answer with pictures of my broken plate

  13. ADC is AKM AK5353. There are two of these – one for MIC and one for AUX-IN. It is pin and power-compatible to a better AK5386 ADC. I may try to upgrade the ADC to see if it improves the AUX-IN quality.

    There’s no DAC and no CAN (at least no PHY). All control messages from DCAN and KCAN are relayed by MOST gateway in the head unit over optical MOST bus. Audio output is encoded also encoded into the optical MOST bus. Depending on the options of the car, the DAC is either in the head unit (HiFi), or in an amp in the trunk (Top HiFi).

  14. Certainly interesting, though I don’t know exactly what you mean when you say you’re going to try swapping it out. The ADC in the MULF is surely for mic input only – the aux in harness goes to the headunit. As far as the aux in itself, I suppose it’d make sense if the analog in were routed through an ADC, handled digitally, then routed back to whatever DAC the headunit uses for CD audio (something onboard for hifi, or something in the amp for Logic7), but it’d make equal sense if it weren’t.

  15. It is not for MIC only – there are two stereo ADCs – one for MIC and one for AUX-in. With option 6FL the AUX-in in the head unit is inactive. AUX-in on MULF2HI is the one that is processing audio.

  16. Hi
    I have a mulf high 9224674 2010 built and I can make and receive calls and use the USB. Buy I am unable of download the contacts of the phonebook, using Samsung Nexus Google, neither using android 4.3, 4.4 or CyanogenMod 11. Do I need an update for the software of the mulf, in case how do I ask for in the dealer?

  17. Hello Alex, i have a problem with my originel bmw mulf. Bleutooth is working properly, but usb isn’t working anymore… aux function is works…. Can’t select usb function it’s light grey…..Already new software on the mulf and coded it twice… but it won’t work…… probably something is broke inside the mulf….. maybey you know where the problem is, if i can fix it myself… It’s a 2007 bmw e87…..

  18. I have a 2006 e90 325i with no Bluetooth, microphone, and so on. Just AUX. I’m looking to add the USB function, and if that comes with Bluetooth that’d be cool too I guess. lol I’d like to know what I need in order to accomplish this. Thank you.

  19. Hi I had the same problem with mulf 2 on e61 lci with cic retrofit. 1rst case the mulf2 didn’t recognnize my bluetooth devices. I disconnect the mulf2 after 1hour i connected it back and then it has worked again. But now after 2 months i have decided to pair my s6 and then nothing….nothing with s6 or old phone…..i disconnected the mulf2 again but nothing….so i bought a new mulf on ebay and then the reseller ask me the vin to input inside the mulf. Now i still waiting for delivery and will try and hope it will work again…

  20. Hi Alex,

    I am having problems with MULF MODULE in my BMW 530i 2006 (E60), the bluetooth functionality does not work, what is the best way to fix it.. Thanks

  21. Hej Alex,

    I have a problem to with bij E90 Mulf BMW from 2005.

    My mulf is broken and I may like to update my BMW with a mulf2.

    But it is already okay to work with a mulf1 version. But can I just buy a used one? Do I have to program something? I have all the tools to program.

    Just let me now.

    You can also directly contact me by email.


  22. I honestly don’t have an answer for you, I’m not sure if the MULF1 and MULF2 are compatible. It I believe it’s the case that you can just buy a used MULF1 as a replacement and put it in with no additional work, but I’m not certain of that either.

  23. You can replace MULF with MULF2-HI. You may need to rewire the connector. Also to code and/or program MULF2, you’ll need ICOM – don’t even think about trying this with K-DCAN.

  24. @ Alex, Oke when I just buy a mulf 1 than its just plug & play? Or do I need to do some recode? And is the Mulf1 compatible with new mobile phones?

    @ Sergey, Aha the mulf2-Hi will fit. Rewire the connector is absolutely no problem. But I don’t have ICOM and also no one that have ICOM. Can I download it somewhere? And if I understood correctly I cannot use my K+DCAN cable for programming MULF?

    The reason I want to switch to the Mulf2 is because of the Telephone support. Cause I am not sure if the for example Galaxy S5 or S6 will connect the old 2005 Mulf1 module.

    Please advise me,


  25. Hello all,

    What is just did was only plug-out the Mulf 1 and replace it with a Mulf 2.

    It works. Just cut a bit of the original connector (Bluetooth antenna and wired connector with mic etc.) and it runs. No coding required. I had already the Bluetooth prepare option standard in the option list of my BMW e90 2005.

    The only problem I have now is using the phonebook. That part doesn’t work. So I have to figure out what the problem is. Anyone any idea?

    The USB option I will activate later but not prior on this moment.


  26. Hi Alex,

    I’ve recently added the bluetooth option to my 2007 e92 with USB / MULF2 High SVS fitted as stock. All it took was a bit of coding to activate the tel option but after disconnecting the battery as a precaution when wiring up the mic and antenna, I’ve lost AUX, USB and TEL. AUX is missing from the audio menu and USB/TEL are inactive (two dashes shown in radio display).

    Have tried re-coding several times without successes. MULF2 seems to have power (red lights visible on output/input). Have checked all cables – any ideas?


  27. Hi Alex,

    I am thinking if it would be possible to read the data that is normally sent over the ODB2 cable over bluetooth, just from software.
    I mean to make a custom software and read this data through some hidden protocol.

    Thank you,

  28. Hi, did anyone got an issue fixed when the mulf2 does not read phone book from the phone? It was workign fine with mulf1 but not with mulf2 high.

  29. Hello my beemer,

    Yes I do so same problem over here.
    Did not fix it yet due to time issues. Can provide you some options to check / test. I did not try anything myself.

  30. My beemer

    Good news. How did you do. With empty man file okay. Strange baca use what does the system do when it’s empty? Just erase of factory settings? En did you change the date back again after the man file? Did you change your vin also?

  31. My son recently bought a 2011 328i with options 6FL and 620, but not 644. He wants to activate bluetooth, but needs to know what the BMW part number is for the cable that goes between the MULF2 unit and connects to where the BT antenna resides under the dash. We have not had any luck determining this yet.

  32. My beemer,

    Yes also worked on my side. Now my 6fl USB functionality my ccc does not see it. Already include +kmp3 and + ipod and 6fl to vo. And did both frm and cas. Also empty man file to ccc and mulf2 but now USB working not even a voltage on USB I think because my USB is dark.


  33. Hi Alex,
    My 2008 535xi wagon. Mulf was damaged by water. Can I purchase the Most fiber optic loop to bypass the Mulf. I dont care much for the blue tooth and understand it may not work but I believe I might at least get sound back again. Thoughts on this would be apreciated Sir.

    Sean in Toronto

  34. I can’t be sure having never tested it, but my understanding is that yes, you can get a loopback block that just optically connects one side to the other to bypass the module totally, and that should accomplish what you’re after.

    You’ve got 3 options for doing this: The simplest is to pull the two fibers out of the connector that the MULF uses, and just tape them end-to-end. That’s probably not going to be super reliable, though, if it even works well enough. The second is to reorganize the jumper block behind the driver-side rear seat bolster. If you pull off the rear bench, then undo the two T50 bolts in the center of the backrest and unclip the upper seat clips in the trunk, you can get access to the MOST distribution block. There’s one fiber coming from the front, and one going to the front, with the two fibers to/from the MULF connector in the middle. You can pull the “to front” fiber out from where it is, and plug it in opposite the “from front” fiber to bypass the CD changer and MOST in the trunk. That should work. Lastly, probably the simplest option is to find the part number for the MOST diagnostic port terminator on the pedal trim in the driver’s footwell. There’s a MOST connector up there that you plug into a portable tablet for diagnostic operations, but when it’s not in use, the in/out fibers are optically connected together with a terminator block that sits in the pedal trim. The connector is the same, so if you pick up another of those, you should be able to connect it in the trunk instead of the MULF and get the same effect without any work whatsoever. And it’s immediately reversible.

  35. Alex:

    I’ve found tons of information on the internet, but none of it is terribly reliable, so I’m hoping you could provide some insight. I have a 128i with TCU1.5 / professional navigation / BT / Logic 7. I’d like to piggyback a MULF2 onto this in order to have a big SSD in the trunk with all my music. However, I am unable to find details on how to connect the MULF2 to the TCU via multipin connector (fakra and MOST more-or-less makes sense).

    Any ideas?

    Also, I’m assuming I’ll need to code 6FL to enable USB. Car just missed out on combox (was built 12/09), sadly, as that would make everything easier.

    Thank you.

  36. Unfortunately, I’m not really sure about your case. I THINK the way it works is that the MULF gets only USB pins, and the TCU handles bluetooth calling. But that’s basically a mix of vague recollection and guess.

  37. Hi Alex,
    As a lot of people over the world my Mulf2 (not the high SVS in my case) loosed the Bluetooth
    I don’t know if it’s heat related but it curious how all the mulf’s generation starts to broke that way and finally needs replace.
    I’m pretty shure a simple hack could repair most of the mulf 1/2/2 high svs.
    Where will you start to look if it’s overheating and bluetooth issue?
    Thank you in advance

  38. Hi Alex,

    Mi mulf2 got wet when a bucket of salt water turn over in my trunk. I was able to dry it and got the phone (Bluetooth) to work after I dry it and clean the wires on the blue pin. But unfortunately my USB still not work. Do you know what could I replace to make it work or know who will fix it for me?

  39. Hi Alex,

    One component burned out on the board and unfortunately I cannot find the specs for this component. By the any chance would you know where I can find the schematics of this board?

  40. Hi Vinny- Unfortunately, which components precisely will depend on the specific incident, and may be quite difficult to diagnose. That’s why companies almost always replace the whole item (or recommend you buy a new one) for water damage situations. If I water damaged mine, I wouldn’t even bother trying to figure it out or repair the board itself.

  41. Definitely no chance of finding a schematic anywhere. It’d probably be possible to determine repair part number/value by comparing with a working unit, but that’s about it.

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