Problem: The customer’s concern was that the radio worked one day and not the next. All of the radio lights were on but no sound was coming from the speakers. There were no DTCs.
Details: This radio is equipped with the MOST (Media Oriented Systems Transport) bus network system. Any break in the fiber-optic cable will cause this kind of issue. The MOST bus connector is located in the trunk near the left rear seat above the wheel house. This location is the best place to perform MOST system tests and to see if light is present in all fiber-optic cables. In this case, the technician found a mouse nest near the MOST bus connector and one fiber optic line had sustained some mouse-inflicted damage. (see image).
Confirmed Repair: The shop bought a fiber optic repair kit from a BMW dealer and fiber-optic crimping pliers to repair the line. After the repairs, the radio worked normally and sound was restored.