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Combox Retrofit Guide


How to retrofit the CIC Combox


Despite being a mod which has been done for several years, I found myself struggling to get all the information in one place and consistent. So here is my guide for the combox telematics retrofit on my 2009 E93 335i with build date 10/08 which is equipped with a TCU+MULF2. I tried to accommodate with the information I found for the other variations, but not everything is covered as there are some exceptions to this process.

Firstly, you need to understand that your car can be one of three variations:

1) TCU and MULF
2) TCU Only(Telematics Control Unit)
3) MULF Only (Media? Universal Ladefreisprechelektronik)

This means, your car can have a TCU and a MULF(Options 6FL and 639 or 633), or just a TCU(Options 633, 639 or 644) or just a MULF(Options 6FL or 6FL + 644).

When upgrading to the Combox, the other module(s) are removed entirely, so only the combox will be installed in the car. If you have both a TCU and MULF modules, there will be an extra fiber optic MOST connector(two green wires) that need terminated so the MOST ring continues to operate properly. There are actually two MOST connectors, but since you are replacing two modules (TCU and MULF) with one module(Combox), you'll have an extra MOST connector unplugged. Since the MOST ring is a fiber optic network, they need terminated properly.

The TCU and MULF modules are located in the trunk of the car, depending on which E Chassis vehicle you have. This guide will cover the locations for the E93, but the wiring and connections are identical across all E chassis. It is not necessary to make a retrofit harness, however this guide will assume that is being done as it retains the stock mounting locations. The biggest variable to this installation is the USB hub and if you need to account for it, personally with my configuration I did not. Depending on the options your car came with or has had retrofitted(6FL/6NR etc), this hub may be in the trunk or located in the driver footwell or may not be present at all. There may be cases where you may have retrofitted something or may need to move wires to and from the USB hub, and because of its varied placement and presence, you have to just figure this out yourself. In my case, it was not a factor and will likely be that way for many others.

Here are the items you'll need to buy for the harness:

Combox Side:
61136913644 - BMW 26 pin Connector
61136913626 - BMW 26 pin Socket Housing
61131393726 - x20 Female Socket Contacts

TCU Side:
Kufatec 37758 - 54 pin Connector (If you have both TCU and MULF, you'll need two of these)
61130006664 - x20 Male pins with extensions

Special Tools:
Open barrel Crimper (Optional)

MOST Terminator - 61136931507 or 61136917541 (For TCU+MULF cars, take your pick)
USB HSD Cable (Depending if you have a USB hub, where its located and how you route it). This is probably the biggest question mark when it comes to this retrofit, some people may needs this and some may not. You'll just have to tear into your trunk and see what you've got. There are three lengths of HSD cable sold by BMW:
  1. 61119129361 (3370mm = ~ 11 feet)
  2. 61119202749 (2210mm = ~ 7.2 feet)
  3. 61119129360 (2330mm = ~ 7.6 feet)
Combox Connections:
Once you've made your harness, you'll have various cables with fakra connections you'll need to plug into the combox. On the right side there are two little black plugs that are very close together and will not fit. So you'll need to buy a Fakra jack double B right angle to TWO fakra plug Z adapter. The plugs on the combox will connect to this double b jack, and this gets converted to two z plugs. These z plugs will be inserted into the jacks that used to hook onto the TCU. These jacks are Fakra B and Fakra D, but Fakra Z plugs are universal and will fit. TLDR: You can buy this cable from here:


Note: For the pins and socket contacts, you may need less than 20 depending on which type of combox you are connecting. However with the Combox Telematics on a TCU+MULF car and enabling BMW Assist, you'll need 18 and that is without messing any up during crimping. Also, if you don't have sat radio this is a good time to retrofit it as the module hooks up in the same places.

Retrofit Harness

To start off making the PnP harness, make sure you have these items(There is actually a second kufatec connector, not pictured):

Now take the kufatec socket holders and stick them together with the tabs facing right and the larger opening facing you. Pin #1 is the bottom left, Pin #18 is the top left. Pin #19 is the bottom middle, Pin #36 is top middle. Pin #37 is bottom right, pin #54 is top right:

Now you need to crimp the female socket contacts onto the wire ends. You may need an open barrel crimper, here is a video on how to do this properly:


Start by putting one of the female pins into Pin #1 of the Blue BMW 26 Pin connector. Now take the other end with the male pin, and put it into Pin #17 of the Kufatec 54 pin connector. This wire is the same for all three harness combinations. Keep in mind, if you have a TCU + MULF, you'll be creating a Y cable where half the wires from the BMW 26 pin connector go to one Kufatec connector and the other half go to the other. Each Kufatec connector plugs in to the original harness that used to go to the TCU and MULF. These plugs then merge into one 26 pin connector that plugs into the Combox, which assumes the duty of both the TCU and MULF. Finish building the harness using one of the tables below, BOLD pins are optional if you're installing a combox media and not a combox telematics:
BMW PinTCU PinMULF Pin Description
117 Power T30
217 Power T30
3Phone Cradle Power?
5 CAN HIGH (Connect to PDC Module)
6 CAN LOW (Connect to PDC Module)
1022 AUX GND
1121 MIC BLNC (Shield)
1219 MIC-
1436 Ground
1533 TEL Wake Up
1750 NOTRUF L (Emergency Button LED)
2038 LS NOTR- (Emergency Speaker)
2137 LS NOTR+ (Emergency Speaker)
2223 AUX BLNC (Shield)
234 AUX NF L
245 AUX NF R
251 MIC+
TCU Only:
BMW PinTCU PinDescription
117Power T30
217Power T30
5CAN HIGH (Connect to PDC Module)
6CAN LOW (Connect to PDC Module)
10AUX GND (Connect pin from AUX connector if added)
1533TEL Wake Up
2038LS NOTR-
2137LS NOTR+
23AUX NF L (Connect pin from AUX connector if added)
24AUX NF R (Connect pin from AUX connector if added)
MULF Only:
BMW PinMULF PinDescription
1 17Power T30
217Power T30
5CAN HIGH (Connect to PDC Module)
6CAN LOW (Connect to PDC Moldule)
10 22AUX GND
11MIC BLNC (Connect pin from added mic)
12MIC- (Connect pin from added mic)
14 36Ground
15Not Connected (TEL Wake Up)
23 4AUX NF L
24 5AUX NF R
25MIC+ (Connect pin from added mic)

Be very careful not to break the socket holders or you may break one like I did. Luckily, the MULF side of the harness has one row that is completely unused, so I swapped them over, super glued it and put the connector together:

When you're done, if you have a TCU+MULF car, the harness should look something like this:

Installing Combox

Once you have the harness made, you'll need to get access to the combox. In the E93, you start by removing the floor of the trunk and you'll be able to see half of the modules. On the right, there is the TCU and below it is the MULF2. On the left, there is the Sirius sat radio module.

To get access to the back side of the modules, you'll need to get in the back seat and fold down the back rest. Open up the ski pass and you'll see two oval shaped plastic covers. Pop these off and use a 10mm socket to remove the screws. The plastic housing for the ski pass should come away from the tunnel.

Now go to the trunk and remove the four torx bolts starting near the bottom bolts, pull back on the housing and you'll hear it pop after a fair bit of resistance.

Do this to the other side and the trunk side of the ski pass tunnel should come out also. Next, there is the carpet covering, I personally left this in because the push rivets did not want to come out. You can just pull back on it and the foam piece will come out, exposing the back of the modules:

From this point, its pretty straight forward. I recommend taking photos of all the connections and so you can remember which colors go where. Go ahead and remove all the modules, its a pretty straight forward process. Try to remember where everything goes because it helps when trying to understand what you're moving. The TCU and the MULF(If you have them) can be removed completely.

Transfer the one black plug from the MULF2 and connect it to the black jack on the combox(the blue jack on the combox is NOT used in this configuration). Take the blue 54 pin harness that used to go into the MULF2 and the white 54 pin harness which went to the TCU, and plug them into the appropriate connectors on your retrofit harness. When you do this, you'll need to take a box cutter and cut off some fins so the connector will fit. If you forget which connector is which, the MULF2 has no pins on pins 37 through 54.

Take the MOST connector that went into your either your TCU or MULF (depending on which way you will mount your combox will dictate cable lengths and orientation), and connect it to your MOST terminator. Take the other MOST connector and plug it into your combox. Next, take the 26 pin connector which both 54 pin connectors merge into, and plug it into the combox.

At this point I had three Fakra jacks left to plug in from the factory cables, white(Bluetooth), black, and maroon(GSM Stuff). The white jack connects to Fakra B to Fakra G adapter you bought. Plug the other end of this Fakra adapter to the white/yellowish plug on the combox, (left of the black USB connector and two spots left of the blue USB connector). The black and maroon jacks connect to the Fakra Z plugs in your other adapter. Then plug the double B right angle fakra plug into the fakra double b jack on the far right side of the combox.

Connect the USB connector to the black jack, now hook your sat module back up if you have one and install the combox and mounting hardware. You should have two wires coming off the combox 26 pin connector, these need to go to your high/low on the canbus so BMW Assist will work.


Looking for a member contribution on this part since I never did this myself.