For some reason this morning when I go into my stereo to choose AUX so I can play music off of my usb drive, the AUX is greyed out and not an option. It was working fine yesterday. Also is just so happens that my bluetooth is not operational either. It says that bluetooth is switched off. But I cannot switch it on. My phones bluetooth is on. Any reasons why both would just go out at the same time?

 

There must be a problem with the MULF ecu. Perhaps it is a bad connection or a kink in the optical ring.

First thing to check is the MOST programming interface at the co-drivers footwell. It must be properly closed and as straight as possible.

If that does not help, you will need a computer with BMW software to help you troubleshoot.

 

Thank you for the information!

 

I just noticed that my SAT feature is greyed out as well. So I have lost my AUX, Bluetooth, and SAT. Navigation still works, AM/FM radio still works, and the ability to play CD's is still available.

 

That confirms my suspicion, that you have a problem in the MOST ring. Either a module has gone bad and is interrupting the rest of the modules (as they are on a ring), or (most likely) the fiber-optic cable connectors are not properly attached. Navigation and FM/AM radio are on the head-unit and so do not need the ring closed to function.

If it is not the MOST programming port, and you see light coming out of the cable when open, you will need INPA at the very least to help you diagnose the problem. There is a procedure in there which helps determine between which modules the ring is open.

I don't know if you know how the MOST bus works, so i'll explain it here briefly:
1. Each ECU in the MOST ring has an optical input and an optical output.
2. The signal travels from ECU to ECU until it reaches its destination.
Lets assume you have ECUs A, B and C on the ring, connected as :
A_OUT->B_IN
B_OUT->C_IN
C_OUT->A_IN
So if A wants to send a message to C, it must go through B. And if B is non-functioning then C never gets the message. The same holds true for the cabling: if any single line between the ECUs fails, then NO module will function, as the ring is open.

This is different to CAN bus , where ECUs are endnodes: a failed ECU does not necessarily impair the rest of the network.

 

Thank you very much for taking the time to help me! I am trying to decifer what you suggested above. On the passenger footwell is a door. I open the door and will see is the MULF ecu. I am looking for the optical ring and making sure there are no kinks and as straight as possible. What do you mean by "it must be properly closed"? Thank you again for your help!!!