beebe

I bought a 2008 audi Q7. It has the bang and olufsen sound system. When I turn on the MMI the audi logo comes up then goes off. I replaced the control board under the buttons in the center console. Same problem. I did a VCDS scan.

It shows 47 - Sound system. Electrical error and Optical error. Also 37 - Navigation optical error.

What is the "47 - Sound System"? I'm guessing that's what needs to be repaired/replaced? Where is it located?

Thanks,
Roger

tigerwillow1

There are a bunch of devices daisy-chained on the optical (MOST) bus. What I've read says that if any of the devices goes down, the optical loop is broken and none of the devices work. The MMI starts up, then shuts itself down. To allow the functioning devices to operate, the failed device's optical connection is bypassed with a loopback gadget. Here's a link to an example. There are lower cost aftermarket versions: https://www.amazon.com/Genuine-Audi-Loopback-Connector-4E0973802/dp/B00YWC3GFI

As for location, look under the rear floor, to the right of the spare tire. With the bose system, that's where the radio is. I'm guessing that's the same for other radios.

beebe

To the left of the spare tire is the B & O Amp (I believe). But it has no optical connector. So I'm guessing that's not what's called the "47- Sound System"

beebe

To the right is all this other stuff.