Sequoia MOST bus fault

Greetings. I understand your frustration. The symptoms you describe align with a malfunctioning MOST (Media Oriented Systems Transport) bus. The MOST bus is a fiber optic network used in some vehicles for high-speed data transmission between control units, primarily those related to multimedia. If one of the control units on the bus fails, it can disrupt the entire system, leading to the issues you're experiencing. I encountered a similar issue on my 2018 Audi A6. Have you checked the fuses related to the audio and navigation systems? Sometimes a blown fuse can mimic a more complex problem.

Thanks for the info! I did check the fuses, and they all seem fine. What exactly does 'control unit' mean in this case? Is that something I can check myself, or am I looking at a mechanic visit?

A 'control unit', in this context, refers to an electronic module responsible for a specific function, such as the radio tuner, amplifier, navigation computer, or DVD player, all of which might be connected via the MOST bus in your Sequoia. While it's theoretically possible to diagnose the specific faulty unit yourself using specialized diagnostic equipment and software to monitor the MOST bus communication, it typically requires a level of expertise and tools beyond what most individuals possess. Considering the complexity and the need for specialized tools to pinpoint the exact module causing the fault, I would suggest consulting a qualified workshop with experience in automotive diagnostics and fiber optic systems. In my case, with the Audi, the dealer had to use their diagnostic tools to pinpoint the faulty module. After replacing it the repair cost was about 1000€.

Thanks a bunch for your help! It sounds like this is beyond my capabilities. I'll take it to a workshop and have them diagnose the MOST bus. I appreciate you sharing your experience with the Audi; that gives me a good idea of what to expect.