[Luper52]

I've looked at as many of these threads as I can but still can't find any definite answer. I've done as much testing as I can do in the limited time I have. Can't work on it much while I'm at school and it's raining practically all day while I'm home for vacation. My car is a 2007 E90.

So the error is "No Warning Tones" and I have no sound both with music/radio as well as system alerts. No water in the amp/satellite nor at the combox.

When the error occurs, I have no red light at the driver's footwell MOST diagnostic loop.

Steady blinking red light coming from:
- Logic7 amp
- Combox module (retrofitted)
- Satellite module

Error still occurs when fiber optic disconnected:
- Logic7 amp
- Combox module
- Satellite module

I only have a MOST termination loop that fits the combox's fiber optic plug, so I was only able to test the loop on it. Still get the error.

Cables seem to be all sturdy and connected at the MOST distributor on the rear seat pillar. It could be noted that I recently did a folding rear seat retrofit, and shortly after I started experiencing infrequent static ticks while listening to music. Other times the music would stutter but continue playing.

From my understanding the MOST system goes like this:
CIC -> AMP -> Combox -> Satellite -> Footwell Diagnostic Terminal

So this must mean there is a disruption between the Satellite module and Footwell Diagnostic Terminal, no? I've read that the fiber optic cables rarely fail, but anything is possible. Like I said, the fiber optic cables that I can see after taking off the rear seat side bolster don't appear to be pinched at all.

I am able to get it working sometimes by reconnecting all of the fiber optic lines and then going to the MOST distributor and pushing all of the lines back in to make contact. At least I feel like that made a difference. Is always hit or miss.

[Luper52]

SOLVED!

I was right that the problem was between the satellite module and the footwell diagnostic terminal. It was the satellite module. I figured out that I actually can take apart the fiber optic loop terminal without destroying the housing. After getting faint red beams at the end of the footwell fiber optic connector, I kind of figured it was the satellite module.

Sure enough after looping the fiber optic port where the satellite module is, sound came back and everything is back to normal. Man what a pain! Hope this diagnosis with closure helps those who are struggling on the same issue. A lot of threads I found neglected to post the solution, so here it is!

For those looking for what terminal loop I used, it's this OEM BMW part: 61136917541

Along with a helpful instructional resource: https://www.bavlogic.com/?p=3729

[ctuna]

Those jumpers are available on Amazon much cheaper than from
BMW.

[Luper52]

Originally Posted by ctuna

Those jumpers are available on Amazon much cheaper than from
BMW.

Yes agreed but if you're near a BMW dealership it's much more convenient. Either way the part number is on some of the Amazon listings as well so it never hurts to have a part number.