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      01-17-2022, 11:48 AM   #1

Drives: 335i LCI, ZPP, ZSP, ZCW
Join Date: Apr 2018
Location: Dunwoody, GA & Boston, MA

iTrader: (0)

(Yet another) Combox Retrofit

Hi All,

I decided to retrofit a Combox to my 2009 335i after the TCU started to drain the battery. Thereís a lot of info scattered between various forums detailing the install, with some interesting info and detailed pictures, but some of it is either outdated or a bit hard to follow. This will be a brief write up with my experiences installing the Combox, with info updated for 2021.

Background / General Info

I have a 2009 E90 335i. Itís a pretty well optioned example with CIC iDrive, USB Audio, and BMW Assist (I have many other options as well, but those are whatís relevant to retrofitting a Combox). I also have experience retrofitting BMW tech, having retrofitted the original BMW MK4 nav system to my old E46 (way more involved, had to take apart most of the interior to do it!). This retrofit is much easier!!

Your car may vary in options. If you have the Premium Package, you have BMW Assist, which means you have a TCU (Telematics Communication Module). I pulled my old one apart, and it consists of a bluetooth board and an ancient, 2G GSM car phone for SOS.

The SOS system will not work, even with a brand-new combox from BMW - the ď4GĒ Combox is really a 3G one, and will not activate on modern cell networks. I would assume that this is because the original TCU used in the E46, E53, etc (iBus cars) was the TCU 1, the TCU (MOST bus) used in the E9x cars is the TCU 2, the Combox used for the E9x is the TCU (Combox, using 2G GSM tech) 3G, and then the updated one used later to placate owners under the original BMW Assist plan was the TCU (Combox, using 3G GSM tech) 4G.

BMW Assist is option 639.

In addition, if you have a USB port in your center console the you have the USB/iPod interface as well. For 2009, this was a standalone option, and the order code was 6FL. This option means you also have a separate module mounted below the TCU in the trunk, called the MULF-2.

If you donít have iDrive, and donít plan to retrofit, a combox is practically useless. If you want to add iPod integration, consider the much cheaper MULF-2, as youíll still get iPod integration. All of the nice stuff a Combox confers (Bluetooth audio, album artwork) are only available for the iDrive.

You may also have a center console dock for a phone - this is a separate option, and was not available in 2009. This option is 6NF.

Wiring / Cable Routing Info

Iíll try to summarize as succinctly as possible:

If you have BMW Assist, then your bluetooth wire is routed to the TCU. This applies even if you have 6FL!

***If you have only BMW assist, then your Aux input is wired to the CIC - youíll need to run three cables (AUX L & R, plus the shield wire) to the back of the car where the TCU lives.***

If you have 6FL, then your USB cable is routed to the MULF-2. The Aux wiring is also routed to the MULF-2 (which saves time later!)

If you have the center console dock, then you have a USB hub, which is then routed to the MULF-2. I have no experience with this, so this is where my knowledge ends, sadly.

*** The MULF-2 has a built-in USB hub. Thus, if you have 6FL but donít have the center dock (which I suspect is the vast majority of cars) then you donít have to worry about messing with a USB hub.***

If you have both 6FL & BMW Assist, then youíll need a MOST ring adapter. This is because the fiber-optic network relies on continuity between each module to allow for data (in the form of light) to be transferred, and the Combox replaces both the MULF-2 and TCU.

Choosing a Combox & Installation

***ONLY use a BN2000! Do not use a BN2010 / BN2020 Combox, as they use different communication protocols. It will not work reliably!***
When in doubt, the big connector on the combox must be black.

Pro tip: When looking for a Combox, look for a bluetooth module out of an E84 (X1) or E89 (Z4). These were the last Exx produced, and came with Comboxes standard in the last few years of production. Chances are theyíll be much cheaper than informed eBay sellers who retail the Combox for $150+. I bought mine for $107 (including 7% sales tax).

At this point, it doesnít matter if you have a Telematics Combox or a Media Combox. Telematics wonít work!

You can elect to use an adapter harness from the forums / eBay (I actually will be posting one for sale) but you can easily re pin the connectors from the MULF and TCU. The MULF connector is blue, the TCU is white.

The pinouts are attached as a JPG, from another writeup here.

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Pretty easy to follow, though having fold-down seats makes this much easier! You should be left with one wire on the TCU side (PIN 3, which from what I gather is meant to power the non-existent dock in the center console), and two wires from the MULF-2.

The black USB wire from the MULF-2 connects to the Combox.
The beige bluetooth wire is a bit trickier. I actually bought a Combox wiring set from a crashed 335is off of eBay, thinking I could use the bluetooth connector housing with my existing wiring - save your money, because this wonít work (the newer housing was too big to fit on my 90ļ angle connector from my car).

I ended up using a pick tool to pop the magenta clip up on the beige housing, and then used a butter knife to slowly work the housing off of the metal connector itself. The bluetooth wire can then easily click into place on the Combox.

If your wiring job is successful, then once you plug in the Combox to your connector, the MOST lights on the Combox should light up! I had neglected to transfer the power wiring from the MULF-2, and so it didnít come on correctly. This is your first point of triage. If the Comboxís MOST doesnít light up, check your wiring!!!

Iíve attached how I routed the Combox & wiring. It may be a bit awkward getting it to all fit, but youíll figure it out, Iím sure!

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You should then be able to code your car. Change your VO using NCS Expert to have the following options (this is adapted from the Coding PDF which is attached):

Change your build date to 0311 (not 0410 as in the PDF. This is not suitable for NA cars, which didnít have the Combox yet!)

Delete the following values: $ 639 (not $633 as stated in the PDF. 633 is the European BMW Assist order code!), $ 612, $ 616

add the following instead: $ 614, $ 615, $ 644; $ 6AL; $ 6FL; $ 6NF (if you have the center dock); $ 6VC ; $ 6 NR ; $ 7 SP

***Keep in mind formatting. There is no space between the $ and the order code (for example itís $6VC) !

Then, default code three modules (skip the KOMBI if you donít have BMW Assist!)

KOMBI, CIC, MEDIA (Media is the Combox!).

Please note that your Combox probably wonít work without coding. Mine came from a 2015 X1, a very base spec one, so it was initially coded for a Professional headunit, no Bluetooth, etc. To be safe, default code the Combox!

Also, Iíve attached the link to the final update for the combox here - simply drag the file to a FAT32 formatted USB drive (Iím on a Mac, so this was important to note. For best reliability, make sure the USB stick is also using the MBR partition map.)

Then, you should be all set! Enjoy the (semi) modern era!

Hope this helps. This was not my own work by any stretch - I used many write-ups compiled by others over the years. This wouldnít have been possible without their hard work!!!

Last edited by Hoody007; 01-17-2022 at 12:09 PM..
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