[RyanTonado]

So I got the dreaded SOSCall out of nowhere while driving. I took the headunit out and the fiber optic cable running into the CD changer had no light so I plugged it back in and went to the trunk. The amp and the cable next to it wrapped in foam, had no light at all, went to the center of the trunk and checked both modules there, no light. I checked under my dashboard for the connector there, and there was a red light, blinking steadily. I’m lost here, where else do I trace this break to?

[ctuna]

so did you actually have a cd changer in the Trunk?
Or just and amp?
There will be unconnected lines to options that are not installed due to pre wiring
and in the Most Bus those lines are not part of the active Most Bus .
They are generally wrapped in felt. As you have shown in your displayed photo's
So there never will be any light coming out of those connections as they are routed
to the inactive block in the most bus.

First thing to know is what stereo system you actually have and which options
on the most bus are installed.

If you got the SOS error it could be anything attatched to the Head unit although
it's not likely a connection problem if you weren't playing with the connections.

Use Mdecoder to see which option's are installed.
If you have the Logic 7 amplifier one of the common problems are they get wet.

Other wise get a Most jumper and move it through the positions.
There are a lot of threads on this already.

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/
Diagnostic Manuals Inpa/Ista D
https://bimmerprofs.com/diagnostics-inpa-part-1/
https://www.google.com/url?sa=t&rct=...7x8H3pN8h1fMuF
https://carmod.ru/files/icom/istad_en.pdf
https://www.e90post.com/forums/showthread.php?t=1681573
https://www.bimmerforums.com/forum/s...-P-actually-do
primary links
https://www.bimmerfest.com/forums/at...9&d=1539905743
https://www.e90post.com/forums/showthread.php?t=1681573
https://www.bimmerfest.com/forums/at...1&d=1590283589
https://www.nathansbmwworkshop.com/b...or-dean-videos

[Hoody007]

An ’08 335i has Logic 7 - check your amp for water damage.
Do you have satellite radio as well? Could be that going bad as well. Or the TCU. Or the MULF-2 if you have USB in the center console.
Your first point of triage will be to purchase a MOST loop and jumper out each module to trace the defective part.

[RyanTonado]

Amp has no water damage, i just replaced it because of that. Apparently the connection under my dash is to my headunit which means thats getting power, does the CD changer come after the headunit or does the amp? I believe my amp is working and fine because I hear a slight static noise from the rear

[ptpending]

if you sos error then you should check TCU module under carpet behind rear seat
it is accessible from trunk

[ctuna]

Do you even have a CD changer because the unplugged in cables next
to the amp wrapped in Fest say you don't .

In the Most Loop nothing comes next because it is a Ring Bus .
Read the Links.

Did things work after you replaced the AMP?

Head Unit connects to Most Test Point under dash that connects to the Most Hub (under passager side bolster in most cars but not the convertible)
Most Hubs connects to all installed modules in the trunk (only the ones that are installed.)