[Underground6t9]

So my radio has been acting up recently, crackling coming from speakers, radio randomly shuts off while paying music. IPOD and blutooth function not working. I replaced my TCU with another used one that I know works, and still have same issues. I put in a loop in the fiber cable and still nothing. Im thinking it might be my radio? Has anyone experienced anything similar?

[ctuna]

The radio does not describe the sound system
There are three different common bmw sound systems
found in a e9x and they are a speaker amp or non amp combo
you need to identify which . The year of the car is a tell in some
cases as the 330 and first year of the 335 in the US came with
l7 top hi fi standard.
The three systems are
stereo no amp 6 speakers
Hi Fi amp 6 channels 10 speakers or 8
Top Hi Fi L7 surround sound 9 channels or 13 or 11 speakers

BMW stereo types
http://www.e90post.com/forums/showthread.php?t=352586
http://www.e90post.com/forums/attach...2&d=1266451970
http://www.e90post.com/forums/attach...2&d=1260829447
http://www.e90post.com/forums/showthread.php?t=343673
http://www.e90post.com/forums/showthread.php?t=138949
http://www.e90post.com/forums/attach...1&d=1209780605
http://www.e90post.com/forums/showthread.php?t=641323
http://bmwcoders.com/forum/3-er-8/bm...1-e92-e93-291/
http://www.e90post.com/forums/attach...1&d=1209780865
http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja
http://www.musicarnw.com/page-2/
http://www.e90post.com/forums/attach...4&d=1278871872

In the amped systems when there is no sound or bad sound a lot of times its the amp going bad or getting wet.( Anything in the Most Bus Loop can stop the sound in a L7 Top Hi Fi system.)

If the radio is just shutting down randomly you could have a low
battery . The IBS can turn things off that it deems not essential
to the cars operation if it detects low voltage. Read the pdf about
the electrical system in the above links if you want to understand this. Its the one in the google search link.

[Underground6t9]

I also have SOS light come on, on start-up

[jbelles330i]

I have been having no sound issues and SOS malfunction light as well. I have a MOST bus jumper but am currently waiting for an additional part for it to test my amp and satellite. I have a 330i 2006. My question is, is where is the main MOST bus connection as I would like to attempt a reset there first. Does anyone know where this is located as it is not in my glove box behind a hidden door.

[ctuna]

The most bus is a ring bus .
The closest thing you can think of as the orgin
or controller is the Head unit or Idrive/nav.
If any one device on it breaks the the ring none
of the other devices function.

[Underground6t9]

Originally Posted by ctuna

The most bus is a ring bus .
The closest thing you can thing of as the orgin
or controller is the Head unit or Idrive/nav.
If any one device on it breaks the the ring none
of the other devices function.

How can you diagnose that?

[jbelles330i]

I went to ECS tuning and located the part (MOST bus jumper) it will allow me to got to each unit-Satellite, amp, and TCU(bluetooth) box. I can unplug the fiber optic cable (its a black cable with a green and black cords). I got this item last week and was able to test the TCU but not the satellite or amp as the plugs were different. Currently waiting for this piece to come in the mail. If the problem is any of these boxes the most bus jumper will allow the fiber optic connction to loop around and my sound should come back but also indicate which box is having the problem.This piece ran me $30.00. So hopefully I can find my answer without all of the exteme expense of the dealership to start. My question is, is that I want to go to the main MOST bus and try to disconnect and reconnect. Any answer to this would be great!

[Underground6t9]

I found my problem connection unplugged underneath drivers side

[ctuna]

Well you don't need this now but , reducing the ring to the least number of
devices or moving a most jumper through the devices one at a time while
always including the Head Unit or idrive/nav would be the first thing.
Verifying the devices one at a time in another car would be another.

There is only one Most Bus all the wires are held together under the Us side rear seat passenger bolster.
If you look at the DIY on adding the cd changer in the DIY subforum
it shows the block where all the most buss connections are held
together for routing.
I am thinking you could make a Most Jumper our of the right size
straw and some tape.

[jbelles330i]

Where exactly did you find it on the driver's side?

[Underground6t9]

Theirs an optic cable underneath bolster just above the obd2 port theirs a panel with 3 screws.