[Seeris]

Haven't had audio in my '07 e93 335i for 4 years as it's my project car and audio came last.

TLDR: Amp was cooked, TCU is cooked, Satellite is cooked.
My thoughts were to replace the amp and use an fiber optic loop to bypass TCU / Satellite just to get it going. Replaced the amp and nothing. The audio system has been worked on before due to a business card being under the satellite box. Strangely enough there's huge amounts of sand around the boxes and in the connectors and a secondary fiber optic at the amp (guessing original).

From my understanding the MoST system is as follows.
Head Unit -> Amp -> TCU -> Satellite -> Head Unit.
My fiber optic at the amp is blinking red so I'm good to the amp. I have no led at the fiber optic for TCU, and obviously nothing at the Satellite box or at the connector by the OBD port. My guess is the fiber output is shot going to the TCU. Are there any videos showing how to get access to the harness and how to replace it for an e93? I've looked at it a good deal and all I can figure is completely pulling the rear seats which I truly don't want to do. Cheers.

[ctuna]

You never mention which sound system you have .
I assume it's Logic 7 option 677.
Did somebody do aftermarket mods if they did anything could be possible?

Logic 7 Most Bus has the connections to the box you mentioned but also a test point in the driver
side panel underneath the steering wheel . I this is disconnected so is the Most Bus.
Also on some cars 07 and later there is both a TCU and Mulf module .
Both of which have a Most Bus connection . Mulf is mounted under the TCU. So there are
two Most connections in that area.

There is a Most Hub where all the Most Cables come together don't know exactly where is on a E93 it
has been discussed here before.
Most test point
http://www.e90post.com/forums/showthread.php?t=347222
Logic 7
https://www.e90post.com/forums/showthread.php?t=1056432
https://www.bavlogic.com/?p=3729
https://www.bavlogic.com/?tag=loop
http://www.bmwlogicseven.com/?p=3837
http://www.bmwgm5.com/
https://www.e90post.com/forums/showt...5#post24455335
http://www.e90post.com/forums/attach...2&d=1260829447
http://www.google.fr/url?sa=t&rct=j&...slMu2A&cad=rjt
https://www.bmwgm5.com/Logic7_E90_91_92_93.htm
http://www.bimmerfest.com/forums/sho...d.php?t=982666

http://www.e90post.com/forums/attach...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+...VCkMqy2aCK09M:
http://www.1addicts.com/forums/showt...php?p=19256760
https://www.teacremotes.com/bmwgm5/

[Seeris]

Alright so I figured it out by sheer coincidence, I guess luck was on my side today.
Fiber optics for the amp AND TCU were replaced and the original fiber optic that was shot was plugged into the TCU. I found the replacement fiber optic for the TCU tucked away underneath the harness (UNREAL).

What I think happened. Car amp had water damage that also damaged the fiber optics, shop replaced amp, fiber optics for AMP + TCU, that fixed the audio. Later on after the car was sold to a new owner, amp got water damaged again. New owner had no idea what they were doing and while trying to fix the audio plugged in the original fiber optic for the TCU back in and buried the replacement underneath all the wires. Since the amp was fried they had no red led at the original or replacement fiber optic for the TCU. After finding the replacement fiber optic for the TCU I plugged in a bypass and have a red led at the satellite fiber optic. Just need another bypass and I should have audio. Never underestimate the stupidity of some people. btw yes it's Logic7

[ctuna]

Water Drains
https://www.e90post.com/forums/showt...hlight=battery
https://www.m3post.com/forums/showthread.php?t=1818373
https://www.e90post.com/forums/showthread.php?t=1566005
https://www.e90post.com/forums/showthread.php?t=1680103

The E93 is very subject to Water Drain problems and has some delicate mechanisms that connect the drains in the up and down position .
I would check for corrosion in the Trunk Area on both sides and especially in regards to the battery compartment and connections.

Fiberoptic are not damaged by water at least the cables aren't as far as I know . It's glass.

They Most system is and Euro Engineer wet dream used by the top three Euro Cars and it's kind of a mess.