[David Eric]

Hi,
It's not mmi problem. Problem is that one of the component not working properly. And you have to find out which, the best way is to use VCDS/VAS or Odis.

Im fairly good at working on Mechanics on my cars but electronics is something I tend to try and keep away from. Any idea what a dealer or repair shop would charge to work on this?

 

[David Eric]

I recommend you find someone locally who has a VCDS/ VAG COM. Run the "Fiber Optic test" under "Applications." Run it under both the standard and 3 dB settings. My guess is there's something wrong with one of the fiber connections in your MOST ring (which includes the MMI, the radio, and the amp (if you have B&O), and the can gateway).

It's a good test b/c it tells you the status of both the electrical connection and the fiber connection for each MOST ring node.

Would the dealership or repair shop be able to do this? Reason I ask is to be quite honest Id prefer going to one place to diagnose and fix the issue as opposed to getting it diagnosed at one location and then going to another for the repair.

A main dealer would probably charge £60-£80 for a diagnosis, which may be refunded if you get them to do the repair work.
Just one question... Probably won't help, but have you tried an MMI soft reset, aka three fingered death grip? Depending on MMI type the button combo varies, but it's in your manual.

I forgot what the soft reset was and have done one before. I have a 2009 A5 3.2 not sure if that helps determine the dials for a soft reset? what are the possible combinations? i can try them after work.

 

[David Eric]

Hey, I'm having the same problem in my 2010 A4, I've got the MMI 3G with Navigation and B&O sound. It seems now that the weather is getting warmer the screen will randomly turn off, and when it happens at night the buttons no longer light up either (the four soft keys, CAR, NAV, TEL, etc.). It's very strange and super annoying. I do have VCDS so I will try doing that diagnostic that gtg196w suggested and report back tomorrow with the results.

Please post results of your findings. May have to take this approach.

 

[David Eric]

So this sounds ridiculous and I'm not sure why it worked, but it did: I removed the actual radio module from the dash (you'll need two removal keys) and unplugged ALL wires from the back. Then I did the same thing in the trunk where the amplifier is, literally unplugged all the connections I could find, blew on them to get any dust out, especially the fiber optic connectors. I hooked everything back up, starting with the trunk, then the actual head unit and it works perfectly now. Like I said, I'm not sure how or why this worked but it did and I haven't had an issue since.

What was the level of difficulty to do this? Did you get a DIY by any chance? Where did you get the removal keys?

I think the most likely answer is that before you were suffering from a loss of signal in the fibre connectors due to thermal variation, which you have now fixed by disconnecting and reconnecting them.

Funny you bring up the thermal variation as this only seems to happen when there is fairly hot weather say over 80 degrees ambient temp meaning it would be 90-95 degrees in the trunk maybe more where the module can be found.

Any suggestions on how to do some simple trouble shooting? Im pretty tech savy and have worked on cars before however German Cars and electronics ive always been a bit intimidated do to their sensitivity.

 

[David Eric]

I would buy a tin of freezer spray and keep it in the car. If and when the issue recurs, locate the fibre connectors and, without touching them, spray each in turn allowing sufficient time for the joints to cool, with one eye on the mmi to see if it springs back to life. Move from each to the next and see if one of them is responsible.

Can I get the tin freezer spray at any auto parts store? Also when you say fiber connectors where would I find those? Are you referring to the module in the trunk or the actual head unit?

I appreciate any feedback