I have a 2004 A8L and the MMI stopped working.I was travelling and stopped and gas station to refuel and when started the car the MMI screen was blank and lost audio as well.I tried to reset but no luck with that.All the lights on the control are out......when ever I hit setup or any soft keys the screen comes on with a MMI and than goes out in few seconds.I have checked my battery and it reads fine.I took it to a audi dealer and they could not figure it out..........they told me it has 7 total modules that they need to test at $110.00per hour.I have also checked the 60A fuse in the trunk and its good as well.I looked at the CD player and the lights come when I try to get the disks out.I have also checked the navigation unit in the trunk and the light come on and the CD's come out. Any suggestions......as to what I need to check..........any fuses or modules.

Thanks
Dave

 

First thing I would do is scan the car and look to see what codes are shown. Then go from there.

 

I did take it to the Audi dealership and after two hours they told me it can take up to another 4 hours to check all the modules.I have 152000 miles on my car and did not feel like spending that kind of money and at the end if they told me I needed a new MMI system.I just don't want to spend too much money on the car.



Thanks
Dave

 

CD changer and NAV are always powered regardless of the status of the control head.

Likely it is a stuck button on control panel - dirt, thread, sticky spills.
Other possibilities include: bad control panel, optical connection, amp, control head.

The way a dealer handles these things without an obvious fix to the problem is to change modules until it's fixed.
Meanwhile the parts and labor meter is running.... easily into several thousand dollars.

First remove, disassemble, and carefully clean the control panel.
Also check all connections - electrical and optical.

As Lazydog said a scan is really the only way to tell for sure.
At $110/hr it doesn't take long to pay for a $349 tool that has many many more uses.
Unfortunately a generic scanner just won't cut it with these vehicles.

 

I took the control panel apart this evening and cleaned it.Did not find any thing sticky in there.Its all clean now and still no radio nor navigation.


Thanks
Dave

 

An optical bus diagnostic would be my next stop after a scan.

Most of these are gunked up control panels, but I have heard of one or two being replaced and fixing the issue.
Without further diagnostics you'd be changing parts blindly.

 

I still haven't got my cd, radio or Navigation to work tried everything suggested on here.Any last suggestions.?

 

No DTCs and optical bus shows "OK OK" on all modules ?

 

Buy an optical bridge from the dealer (not sure for the part number) it should be no more than $20-$25. Once you have it, you may unplug the module that you suspect has the problem and with the optical bridge NOT break the optical loop.

 

I just bought a optical bridge.What usually goes bad the most?Is it the CD player in glove box or navigation unit in the trunk or the radio unit in the trunk??



Thanks
Dave