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Discussion Starter #1
Hi I most recently purchased a 335i 08***8217; and the radio wasn***8217;t working, I tried to raise the volume and nothing happens, both on the ask unit and the steering wheel controls neither have any effect. I read that there is a mostbus system that contains modules that replicate the light and beam it out to the next in line to maintain strength across the distance in which the fiber optics travel, I also attempted to unplug all the modules one by one and use a loop to bypass, and I cannot find the bad module, so far I***8217;ve checked the amp, sos unit, antenna, and the lollipop under the steering collumn. I changed the amp and ask unit, nothing, I changed the volume control module and still nothing. Has anyone had this issue and if so, how did you rectify the problem?
 

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The amp is the most common problem with this symptom.
If you just bought the car as is could do you know what the
story is from the last guy?

Idrive or Pro Radio ?

Dose the display light up?
If so
Does the Idrive controller do anything?
Do the steering wheel controls do anything or
is it just the absence of sound.


Assuming you have the Logic 7 system

There are LED's on the logic 7 amp that indicate its status.
See the first link.

Also if you have a system with a TCU/Mulf the TCU is stacked on top
of the Mulf and it is yet another Most Bus connection.
.

Logic 7
http://www.bmwlogicseven.com/?p=3837
https://www.e90post.com/forums/showthread.php?p=24455335#post24455335
http://www.e90post.com/forums/attachment.php?attachmentid=334282&d=1260829447
https://www.teacremotes.com/bmwgm5/
http://www.google.fr/url?sa=t&rct=j...sg=AFQjCNGF3dULzOZ844U1d0UCTxefslMu2A&cad=rjt
https://www.bmwgm5.com/Logic7_E90_91_92_93.htm
https://www.bimmerfest.com/forums/showthread.php?t=982666
http://www.e90post.com/forums/attachment.php?attachmentid=151088&stc=1&d=1209780605
Most
http://www.e90post.com/forums/showthread.php?t=727663
http://www.e90post.com/forums/showthread.php?t=347222
https://www.google.com/search?q=BMW...hXLqlQKHd81CoUQ9QEINjAE#imgrc=1VCkMqy2aCK09M:
http://www.1addicts.com/forums/showthread.php?p=19256760
https://www.teacremotes.com/bmwgm5/
 

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Discussion Starter #3
No Idrive, just standard radio, the unit turns on and I can cycle through the menus but I cannot raise the volume, it's as if the whole device is muted, raising the knob on both the steering wheel and unit does nothing. I had the amp tested and even swapped with another working amp, and not a sound.
 

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I wonder if you could somehow route the Most Bus directly to the Radio
so there is no devices in between . If you have verified the amp is should
work if the Radio is good and programmed for the proper Logic 7 output.

A lot of times when people change radios they get on that is not programmed
for the sound system they have. There are three basic possibility's .
Head unit is programmed for logic 7 and uses Most Bus.
Head Unit is programmed for stereo or Hi Fi in which case analog
signals come directly from the head unit or the Hi Fi amp both of which
have nothing to do with most bus signals.

How many devices in the trunk floor behind the passanger seats.
It's possible to have a TCU a Mulf and a Sat module and even HD
module in this area.
Early cars with USB came with both a TCU and a Mulf the Mulf is under the TCU in this case.

I have heard there are some software/firmware issues with the L7 amp in some cases
not sure of the details.
 
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