Suzuki APV Audio & Nav System Dead: MOST Bus Failure Fix

As an amateur mechanic with some hands-on experience, I encountered a very similar issue with my Suzuki Swift (2009). The data transmission through the MOST bus network completely failed, causing the audio system and navigation to stop working. After multiple error codes appeared on the control unit, I took it to a specialized workshop. They ran a full diagnostic on the automotive protocol system and found a faulty control module in the MOST bus system. The issue was causing communication failures between different components of the entertainment system. The repair involved: Complete diagnostic of the bus network, Replacement of the defective control unit, Reprogramming of the new module, Testing all connected systems Total cost was 1000€, including parts and labor. The repair solved all issues and the entertainment system has worked flawlessly since then. To provide more specific advice for your case, could you share: The exact error codes showing up, Whether the issue appeared suddenly or gradually, If any recent electrical work was done on the vehicle, Whether other electrical systems are affected This information would help determine if your issue matches what I experienced and guide you toward the most effective repair approach.

Thanks for your input. My mileage is now at 134887 KM, and after reading your response, I realize this might be tied to the fiber optics system issue I had fixed during my last service. The error codes started appearing gradually over the past month. The audio system began cutting out intermittently before failing completely. No other electrical work was done recently. The main error code displayed is MOST-BUS-01, and the data transmission seems completely dead now. The bus system diagnostic you mentioned makes sense as a next step. Would running a full scan be worth trying before component replacement, considering my particular case?

Thanks for providing those details. Your symptoms definitely align with what I experienced, especially the gradual failure pattern and the MOST-BUS-01 error. On my Suzuki Swift, running the full diagnostic scan of the bus network was crucial before replacing parts. The fiber optic repair history you mentioned is significant. In my case, the control unit failure was directly linked to damaged fiber optic connections in the automotive protocol system. Even minor issues with fiber optic integrity can cascade into complete audio system failure. The mileage you cited is close to when my issues surfaced. At that point, the bus system components can show age-related wear. Before jumping to replacement: Have the workshop check fiber optic connections at all junction points, Request testing of signal strength through the MOST bus network, Verify the control unit ground connections My repair costs might have been lower if these checks were done first. The complete diagnostic scan costs around 150€ and could save unnecessary parts replacement. The intermittent audio failure pattern suggests possible connection issues rather than complete control unit failure. Would you be able to note if the system works temporarily after a cold start?

Thanks for the thorough explanation. Yes, actually the system does briefly work after a cold start, usually for about 2-3 minutes before failing again. After checking the error codes this morning, MOST-BUS-01 remains constant, but now MOST-BUS-03 also appears intermittently. The diagnostic scan pricing seems reasonable compared to full component replacement. Given the fiber optics repair history and these new symptoms with data transmission issues, I will schedule the full scan first. Better to confirm the exact problem before replacing the entire control unit. I can track when these audio system failures happen, they seem more frequent during cold weather. Wondering if this timing pattern helps identify if its truly a connection issue rather than component failure? Will ask the workshop to focus on checking those fiber optic connection points you mentioned during the diagnostic process. What diagnostic equipment did your workshop use? Want to make sure I ask for comprehensive testing of the MOST bus network when I take it in.