Shark_V8

I think I've solved my MMI issue and it was staring me in the face. Also had intermittent dropouts and reboots, starting maybe one a week to increasing in freq. To finally not useable.
Found a good video on youtube. displaying similar symptoms on a Q7

Screen would come up, radio play, then reboot.
but my keyboard MMI controller would not work
Steering controls would work
Felt like a power-bus take down or shutoff issue

So I ordered a MMI keyboard off Ebay. Pretty sure it's just that board gone, and judging by the supply on ebay, a common issue.

Jack88

That was my first instinct but the dealer said they isolated the fault to the amp!

Shark_V8

I ordered an amp, as it is a common issue. Installed and no change in behavior.

I've lived with it until last fall. Now the radio basically only works now maybe 5% of the time - but with the keyboard out.
When there is sound, I can still use the steering controls to change station and volume.

The MMI issue, the seating position, parking sensor faults dubious control arms, drove me out & buy the Range Rover > Which has been 100% - no service since I got it.

The RR is spitting a differential fault every now and then, it's driven by a motor built Valeo, the same co that makes A8 starters. Gives you an idea of reliability there. Actually Valeo are OK, corrosion and tight clearances are the problem. I lubed both in-situ, and they are fine.

Jack88

Well, I hope it's the amp, I need to fix this before I can sell the car. The rest of the car is in such good shape and has enough upgrades, it should get more than the average BFM D3 but not if it's got an issue like that. I got the car picked up last night, I haven't had a chance to even take the current amp out for a look. Intermittent failure to me screams loose solder in something critical.

Shark_V8

What you could do is include the amp with the car - don't replace yet. The MMI board is $160 on ebay. I got used MMI unit tonight locally here $200 CAD. Also include as as spares just in case. The not knowing is more of an issue.

Jack88

Well, I got the amp out of the car, which has a weird plug that is not at all intuitive! I disassembled it as much as I could to inspect it, but am limited by how they glue it together upon assembly. They seem to use a lot of goopy glue in it, which I would bet contributes to these things failing. I didn't find anything obvious wrong with it, so I will get an optic loop to install in its place and see if the fault returns with the amp out of the loop. If after a week it doesn't have an issue, I'll order a replacement. If it comes back, I'm going to complain to the dealer and insurance and insist on replacing the MMI controller, since that was close to where the water was and could have conceivably been damaged by condensation or wicking action from the carpet below, see if that works. There was faults in both the control head and optic loop, hence my suspicion of the controller.

Address 07: Control Head Labels: 4E0-910-7xx-07.clb
Part No SW: 4E0 910 732 T HW: 4E0 035 729 A


1 Fault Found:
00384 - Optical Databus
011 - Open Circuit - Intermittent
Freeze Frame:
Fault Status: 00101011
Fault Priority: 5
Fault Frequency: 10
Reset counter: 242
Time Indication: 15

Jack88

The problem is intermittent. I just got the optic loop yesterday, for now I have it in my trunk with the amp accessible. If it goes out, I will pull over and install the loop. If everything comes back, I will know it's the amp. Until then, I drive and wait! It is still possible a loose connection in the bus was the culprit. I did find one connector that was a little wonky, so if after a couple weeks nothing happens, I'd say it's safe to say that was the issue.

Shark_V8

OK Here's where I am at with my intermittent MMI Resets. I work with systems/electronics and to me it feels like a power supply issue. Something is taking down the power due to a component fault which is often caps, failing boards, regulators, chips etc.

So I thought it could be the Keyboard because that is dead too - no lights. Replaced it last night and inspected the board is pristine. - as suspected it's not getting source power.

Which leads to a more obvious culprit that J520 power box under the carpet. Never knew it was there and a bad place for it!

Actually I had an issue with my XC90 also passenger well, but the audio amp. Cavity was filled with water! Drilled some holes for future events and cleaned the roof drains.

Jack88

The dealer replaced the component under the passenger carpet already! Done some driving in the car, so far no issue, but it's only been a couple days and I haven't gone too far. It would be really nice if it was that loose plug.

Jack88

Well, I can now confirm absolutely the amp is faulty. The MMI cutout completely today, so I opened the trunk, installed the optic loop, and everything came back. Upon plugging back in the amp immediately after, everything stayed down and wouldn't come back again. Now, I'll have to dig through the forums, find Jack's contact info and see what I need to do to have him help me with the CP I will inevitably have to deal with on the replacement amp!