[agustincuenca]

I have been knee deep today troubleshooting this issue today, I've read hundreds of posts and watched several YT videos yet I seem to have a different issue or not exactly like the others that solved it.

Problem: no audio, SOS light on the dash. And I lost the SAT feature on the head unit.

What I have:
2008 335i with the L7 or Top HiFi system, 13 speakers.
Non iDrive car.
Modules: Sirius/Sat, Amplifier and BT TCU. NO USB module under the TCU.


What I've checked:
I have fiber light around all the loop, that means, from the HU to the Amp, from the Amp to the TCU and from the latter to the Sirius or Satellite and finally on the diag port/endlink under the steering wheel. There's no interruption on the lights.

I have checked the Amp and it flashes a YELLOW light, it does not have rust of water where it sits (see attached photo).

I bought the fiber optic jumper (https://www.amazon.com/dp/B07PDJPXCW...roduct_details) and tested individually every module, no audio still.

At this point, the only indication that something's wrong is the fact that to the touch the Sirius module is way hotter than the other ones, really hot seconds after unlocking the car or even starting it. So, my only solution now is to see if buying an used one off eBay and replacing it will solve this problem but before doing it I wanted to see if anyone here can give a little more confidence that this is my best course of action.

Thanks in advance to whomever helps me.

[agustincuenca]

no suggestions on why the optic fiber loop won't work? and anyone got this fixed by replacing the sat radio/sirius module?

thanks!

[ctuna]

there are already multiple long thread on how to fix problems
with modules on the Most Loop.

If it was the satalite module when you bypass it with the jumper the sound should come back.
If you have USB there is another module under the TCU called the Mulf 2 hi which has and additional
Most point . sometimes the failing module will be un selectable in the radio menu.
If you only have a Sat and a TCU module and you jump the two with most loops that only leave's only the
amplifier in the loop (well the amplifier and the head unit)

https://www.bavlogic.com/?tag=loop
above tells you what the L7 amp Led's mean.

https://www.e90post.com/forums/showthread.php?t=1948829
entry 2 in the above.

https://www.amazon.com/Velidy-Optica...7RD4GJBC&psc=1

I like the above better as they have the actual housing . You get two but only one of each type of connector adapter.

[agustincuenca]

Thanks a lot Ctuna, I'll keep troubleshooting, I'm getting a second loop.

[agustincuenca]

Originally Posted by ctuna

there are already multiple long thread on how to fix problems
with modules on the Most Loop.

If it was the satalite module when you bypass it with the jumper the sound should come back.
If you have USB there is another module under the TCU called the Mulf 2 hi which has and additional
Most point . sometimes the failing module will be un selectable in the radio menu.
If you only have a Sat and a TCU module and you jump the two with most loops that only leave's only the
amplifier in the loop (well the amplifier and the head unit)

https://www.bavlogic.com/?tag=loop
above tells you what the L7 amp Led's mean.

https://www.e90post.com/forums/showthread.php?t=1948829
entry 2 in the above.

https://www.amazon.com/Velidy-Optica...7RD4GJBC&psc=1

I like the above better as they have the actual housing . You get two but only one of each type of connector adapter.

ctuna Ok, I did extensive reading of your links and troubleshooting, I found the issue to be the Sat module, it interrupts the loop that is restored by bypassing it, but sound does not comes back, I will try to order a module with returns accepted from ebay and see what happens. Unless it can be a fuse?

"sometimes the failing module will be un selectable in the radio menu." the Sat is exactly what disappeared from the menu.

The amp shows the blinking yellow (with the red light on the background), that indicates that the amp is good but the issue is somewhere else in the loop.

I do not have the Mulf 2 or USB module under the TCU one.

Thanks again for all the links and taking the time to reply before, hopefully I'll get this sorted. I will update here.

[agustincuenca]

Going to post an update, been over a year with no sound and I'm lost.

I have 2 loops, I looped the sat and bluetooth modules, one time each and both at the same time. I bought a new amp, exactly same part number, in working order, replaced it, still no audio.

I looped everything, changed the amp, light on all ends, disconnected the battery, did everything, I can't make the car take the bypasses. My last option is the head unit, there are NONE on ebay used, I won't buy a eonon or aftermarket just for testing purposes.

Does anyone figured this out and it was not a fiber loops bypass or any of the many many solutions that are already out there?

[sam9116]

Originally Posted by agustincuenca

Going to post an update, been over a year with no sound and I'm lost.

I have 2 loops, I looped the sat and bluetooth modules, one time each and both at the same time. I bought a new amp, exactly same part number, in working order, replaced it, still no audio.

I looped everything, changed the amp, light on all ends, disconnected the battery, did everything, I can't make the car take the bypasses. My last option is the head unit, there are NONE on ebay used, I won't buy a eonon or aftermarket just for testing purposes.

Does anyone figured this out and it was not a fiber loops bypass or any of the many many solutions that are already out there?

well, since you tried everything else, might as well try rebuilding the most terminal

https://www.youtube.com/watch?v=K3g5sqVK4MU


also check underneath the driver footwell, there is a most bus diagnostic port, if you see fiber optic cable dangling freely, find the plastic piece it supposed to be plugged into.