[Huckleberry969]

In diagnosing some intermittent radio issues, I've seen a lot of posts about the MULF and TCU. What I can't find though, are the differences between the two units...their distinct functions. BOTH seem to be running the Bluetooth (to some individual degree) and BOTH are tied to other phone issues in one way or another. Below are pictures of what I'm talking about in my 2009 E92:

Any help?

Thanks!

[Dracon]

Originally Posted by Huckleberry969

In diagnosing some intermittent radio issues, I've seen a lot of posts about the MULF and TCU. What I can't find though, are the differences between the two units...their distinct functions. BOTH seem to be running the Bluetooth (to some individual degree) and BOTH are tied to other phone issues in one way or another. Below are pictures of what I'm talking about in my 2009 E92:

Any help?

Thanks!

Both have bluetooth ability, but if both modules are installed at the same time, bluetooth is handled by the MULF2 unit.

The TCU is a Telematics Control Unit and responsible for BMW Assist, primarily. It also handles Bluetooth functions only if you didn't order 6FL (USB-Audio Integration) for your vehicle at build time, which is handled then by the MULF2.

The MULF2 (which if I remember correctly is a German acronym for Universal Hands-Free System), is responsible for USB-Audio (Option 6FL - USB port in the center console) and Bluetooth.

[ctuna]

If you have the older TCU and BMW SOS but don't use the SOS
do you change out the TCU or leave it in parallel. And what extra
cables (for the modules)and modules do you need just to get USB besides the one to the center console for USB.
I don't care about SOS I don 't subscribe.
Patick made the comment that is was easy to install in a car that
already had SOS but I wonder if that is year dependent.
I thought the Mulf 2 high was a TCU plus USB.
Mulf 2 high = all the functions of TCU plus USB.
Would there be contention between the two modules if mounted
in parallel. (how does that work?)

[Dracon]

Originally Posted by ctuna

If you have the older TCU and BMW SOS but don't use the SOS
do you change out the TCU or leave it in parallel. And what extra
cables (for the modules)and modules do you need just to get USB besides the one to the center console for USB.
I don't care about SOS I don 't subscribe.
Patick made the comment that is was easy to install a car that
already had SOS but I wonder if that is year dependent.
I thought the Mulf 2 high was a TCU plus USB.
Mulf 2 high = all the functions of TCU plus USB.
Would there be contention between the two modules if mounted
in parallel. (how does that work?)

If you don't care about BMW Assist, forget the TCU and just install a MULF2 High.

MULF2 High is Bluetooth and USB only. The TCU is BMW Assist (BMW Assist is a telematics platform) and Bluetooth (Bluetooth disabled if 6FL is part of the vehicle order).

If you have a TCU, you can swap it out for a MULF2 and all you need to do is run a USB cable between the module and the center console, basically. You can run a AUX cable since technically with 6FL the AUX port is handled by the MULF2 as well, (TCU default is AUX wiring runs to the navigation system). Or you can simply code the headunit to receive AUX directly.

If you wired both the TCU and the MULF2 in parallel, coding will automatically handle everything by adding 6FL to the VO. NCSExpert/ISTA-P will automatically disable bluetooth in the TCU (leaving BMW Assist only active on the TCU) and activate bluetooth, USB and AUX on the MULF2.

However, wiring in parallel will require you to tap into the power and CANbus lines, along with running MOST cabling since there's no pre-wiring for TCU+MULF2 that I'm aware of. It's only prewired for one module unless you ordered 6FL from the factory.

[ctuna]

If you take out the TCU with SOS I imagine
you will have to program out the SOS error or
from the Kombi ? Are there any FSC codes needed
or any Vin coding for the Mulf I see mentioned once
in awhile?
How do you tell if the coding level for Inpa ebidas ncsexpert is
at the right level to make this change?
I have looked at my rad file an it has usb but it is nicht activ.
Could it be as simple as plugging in the hardware and changing this
to usb to activ. Also I have oftern seen the microphone sometimes needs
to be re pinned or is that just for combox,
Also thanks for the reply this makes things much less foggy.
Got the car used and I don't think they even offered 6fl in 06.

[Dracon]

Originally Posted by ctuna

If you take out the TCU with SOS I imagine
you will have to program out the SOS error or
from the Kombi ? Are there any FSC codes needed
or any Vin coding for the Mulf I see mentioned once
in awhile?
How do you tell if the coding level for Inpa ebidas ncsexpert is
at the right level to make this change?
I have looked at my rad file an it has usb but it is nicht activ.
Could it be as simple as plugging in the hardware and changing this
to usb to activ. Also I have oftern seen the microphone sometimes needs
to be re pinned or is that just for combox,
Also thanks for the reply this makes things much less foggy.
Got the car used and I don't think they even offered 6fl in 06.

They technically didn't offer 6FL on 2006 models. Although I coded 6FL on my 2006 with a MULF2 before I sold it, so I know it works at least with the iDrive.

On the Professional Radio, I'm not 100% sure on the specific coding, but it should be as easy as replacing the TCU with the MULF and running a USB cable to the center console as far as wiring.

For the coding, you would need to code out the SOS warning, but you can also remove the BMW Assist VO options and reset it to just telephone prep as well (that's what I did, removed BMW Assist from the VO, installed a FZD without the SOS button and swapped the TCU for a MULF2).

[Huckleberry969]

UPDATE:

The reason I posted this thread is because I'm having intermittent radio issues. I've seen MANY similar posts from other members scattered throughout this board, but haven't found an antidote for the issue. I broke down and took it to the stealership and they confirmed my TCU is going bad (most likely a progressively failing dry solder joint) and they'll be happy to make it right for the low low price of $750. I have the 6FL package on my car, and don't give a damn about BMW assist, so if I can manage to pull the TCU out of the MOST equation, perhaps I can restore balance in the system and hear an entire song again. The question is...how do I do that?

After a couple of hours on these forums, I've learned a few things about the MOST system. Correct me if I'm wrong, but in laymen's terms, it's like a string of Christmas lights with a single point failure. One bulb out, the whole string is shot. So my question narrows down to...what kind of paper clip do I need to use to complete the MOST circuit to bypass the defective TCU and (hopefully) get the radio back (if I can)?

Many post replies point to BMW part number 61136917541, a 7-series termination loop that, in theory, does the job but the 2009 3-series MOST connections don't match this part number's receivers. The car's connector is entirely too large to even THINK about making a connection. So THAT is out! Then there's BMW part number 61136925182. I haven't ordered one of these little wonders yet but from the pics I see, I'm probably going to be in the same boat.

Is there a known OEM method of closing this loop, or am I 1) going to have to pull the wires from the connector and splice, or 2) find an aftermarket loop? This assumes, of course, the loop actually solves the problem.

Thoughts?

PS: By the way, where is the MOST junction box for the 2009 E92's? They seem to be in different places as the years change.

Thanks! Trying to get smart on these cars.

[ctuna]

Most junction box is under the rear passenger bolster
on the US drivers side. There are some installation DIY's
for ipod that show it in the DIY or maintenance section.
I think you could also take apart the end that plugs into
the TCU and point the two fiberoptics at each other through
a straw tape then and you would have a homemade jumper.

This link shows how to spilt the cable at the most plug.

http://www.e90post.com/forums/showth...&highlight=6fl
The cd changer procedure that follows shows the junction box.
http://www.e90post.com/forums/showth...ght=cd+changer

You should be able to follow the Most cables to it from
the Mulf or the the CD changer most cables . The cd most
cables were pre installed up to and including 09.

[jwong77]

Originally Posted by ctuna

Most junction box is under the rear passenger bolster
on the US drivers side. There are some installation DIY's
for ipod that show it in the DIY or maintenance section.
I think you could also take apart the end that plugs into
the TCU and point the two fiberoptics at each other through
a straw tape then and you would have a homemade jumper.

This link shows how to spilt the cable at the most plug.

http://www.e90post.com/forums/showth...&highlight=6fl
The cd changer procedure that follows shows the junction box.
http://www.e90post.com/forums/showth...ght=cd+changer

You should be able to follow the Most cables to it from
the Mulf or the the CD changer most cables . The cd most
cables were pre installed up to and including 09.

I can confirm the location of the MOST junction box being rear driverside seat bolster. Also just an FYI to help diagnose MOST issues, there is a fiberoptic point in the front under the steering wheel. You should be able to search on e90post to find the location of it, but I think that if you are able to find this point, you can see whether or not the MOST loop is complete (not broken) by shining a light into it (I'm not sure, either you shine a light into it, or you see a red light on both ends). Most likely, your TCU is intermittently dieing and causing the loop to break (light doesn't get through).

Sorry for being so vague, I did my 6FL retrofit about 3-4 years ago and my knowledge is fuzzy.

[Huckleberry969]

I figured out how to connect the MOST diagnosis loop to the OEM MOST connector!

So now I have 2 of these the 'diagnosis loops' connected to both the TCU and the MULF and also pulled the large system plugs to both...and I STILL have the radio intermittently shutting down. I'm beginning to wonder if the dealer mis-diagnosed the TCU.

Could it just be the head unit...or something else?

[ctuna]

It wouldn't be the first time.
Did you say you have the L7 system?
Or do you have the Hi Fi?
If you have the Hi Fi the amp is not part of the
most loop.
How's your battery ?
No water in the amp area?
And you have had the Fuse Box recall for the
connector at the fuse box in the cabin.

[Huckleberry969]

No, I don't have the 'L7" system, it's the 'BMW Professional' radio...equipment code 663, so there's no fiber cable running to/from the amp itself. I also don't have the CD changer, just the single disk located in the head unit. I checked for water (and water stains) around the amp, TCU/MULF...dry as a bone.

I checked the battery and it's able to maintain a 12.6V charge throughout the day and when the car is running, reads in at over 14V, so it's safe to say the alternator is working fine.

As for the recalls, being the second owner, I thought the same thing. The dealer tells me the car isn't up for any free service and I double-checked the BMW site by VIN; it tells me there's no open recalls for my car.

One thing I 'have' noticed is that when the fault is cycling, it sounds like the CD player is trying to do SOMETHING. I put a disk in and it's not trying to eject it. Perhaps it's the radio resetting itself and the laser simply following the rail...calibrating to 'home'.

Yeah, this is a strange one. From the reading I've done (scouring the posts), installing that diagnostic loop should bypass the suspected component and complete the circuit. I've installed it on both the TCU and the MULF2...doesn't fix the issue at all. Is there something else along the K-CAN line I should be looking at? At this point, it almost seems the head unit itself could be the culprit.

[ctuna]

I think you are probably right about the Head Unit
being the most likely candidate. Have you tried just
reseating the connector to the Head Unit and all associated
connectors . I would look up that recall for the Power Connector at the Cabin Fuse Box it effected a lot of cars but usually it caused all the lights
to go out and for the car to not be able to start.

http://www.e90post.com/forums/showthread.php?t=1036190
The above describes some common problems with the Pro Radio's

[Huckleberry969]

Thanks ctuna. One question for you... I noticed after pulling the most plug off the back of the TCU that the red light would flash at random intervals. Is that normal...should the fiber signal be a constant stream?

[ctuna]

Don't know what is normal for the most bus .
I just have come to the conclusion that the head unit is what is
equivalent to the server in this network and it interfaces
with the other buses in the car.
I think about the only way you are going to know is to swap it out
with a known good head unit and one configured for you car
maybe hard to find.

electical e90 pdf
http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU

[Huckleberry969]

FIXED!

I replaced the head unit and all is well now! Whew...THAT could have been really expensive. The local dealer wanted some $800 to replace the TCU.

[ctuna]

Can you give the details and cost.
For the records.

[Huckleberry969]

So...I got inside my 2009 E92 one day and found the HiFi Professional radio (non-logic 7/no-Nav) intermittent. Here were my symptoms:
1) No radio (obviously)
2) No door chimes
3) No seat belt reminder
4) SOS occasionally indicator showing up on the dash

I say the issue was intermittent. If the car sat in the sun for a while, the radio DID come back on and all of the other symptoms disappeared. Situation normal. I emphasize this because when the inside of the car was warm or hot, or when the radio had an opportunity to warm up a tad (about 30 minutes of driving), everything was good. It wasn't until the inside of the car normalized to ~50 degrees or so that the symptoms crept back up. I knew I didn't want to spend hundreds of dollars figuring this out so I lived on Google for a while researching everything I could (many of which led me to these E90 posts).

To that end, here's what I checked:
1) Battery charge with the ignition off and with the engine running. The battery consistently held a 12.5V charge on those colder mornings over the course of a week. Additionally, the battery registered 14.X with the engine running. That ruled out the alternator.
2) Next...learn about the MOST fiber system. There's tons of great articles out here on the subject so I bought 2 MOST jumpers for about $20 a pop from ECS tuning at this link: https://www.ecstuning.com/Search/Sit...umper/ES165091 and, one at a time, tried to isolate either the TCU or the MULF2.
3) Put the jumper on the TCU lead...still intermittent.
4) Put the jumper on the MOST lead...still intermittent.
5) Put the jumpers on BOTH the TCU and the MULF2...still intermittent.
6) In frustration, took it to the dealer and paid $129 for what has become a bad TCU diagnosis.
7) Inspected the AMP and TCU/MULF2 bay...both dry as a bone with no signs of residual water collection.

Seeing as how the problem wasn't constant (the temp variable), and since jumping the TCU and the MULF2 out of the system didn't help, I knew it had to be the head unit. I remember reading somewhere about common dry solder joints in BMW audio equipment, a situation occurring where the colder weather enables poor solder joints to contract away from the contacts and expands back to the contacts in warmer conditions. To that end, I tossed the dice and bought a used head unit from a member of these forums for about $100.

I received it today and VIOLA...everything is back to normal! No errors, no intermittent conditions...nothing. The SOS (TCU) error even went away. All totaled, I spent a little over $120 and a couple hours of my time for the whole ordeal. Not too bad, considering the Rope-A-Dope the dealer could have put me in by replacing an item that didn't need to be replaced.

To that end, I have to give a thanks to all who contributed to my (often frustrated) postings as well as those who've posted before. EVERYTHING I read was of value in one way or another and I hope this helps someone in a similar situation at some point down the road.

Bear in mind though, I've read quite a bit about TOTAL audio failures when it comes to SOS errors and weather didn't seem to make much of a difference. To that end, if the error symptoms fade as the car's interior begins to warm, my experience MIGHT be of some help.

[ctuna]

So it played right away with the new Radio
and all your options worked . You lucked out on that
if you didn't have to reconfigure your new radio.


Congratulations on beating the man.

[Huckleberry969]

Thanks. I had some criteria when searching for the replacement. I wanted one that:
1) Came from an E9X
2) Was newer
3) Came from a vehicle with a matching audio set-up (non-logic 7, 6FL package, etc)
4) Didn't have the fading pixel issue that seems to plague some of these units.

The doner vehicle was a 2010 335 with the exact audio set-up / equipment. The owner upgraded and I benefited. 😉

Admittedly, I held my breath a little as I put the key in after installation, but it worked!