MMI Gear Problem Achieved Temporary Fix
05-04-2011, 04:30 PM
#1
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MMI Gear Problem Achieved Temporary Fix
Long story short, the MMI screen gear mechanism can be disabled without permanent damage. Read on...
I've had the dreaded MMI stripped gear problem for the past month or so, where every time I start and stop the car the MMI screen produces the most dreadful cracking/grinding sound, and the screen eventually lost the will to raise and lower on its own - I now need to help it every time. I've almost lost a finger in there more than once, and my manual assistance still doesn't stop the unbelievable noise. It's loud and passengers are frightened/appalled. I haven't had time to bring the car in for service, and haven't decided whether I want to pay for the full mechanism or try to just replace the gear with an eBay one; the first option is extremely expensive, and the second incredibly time consuming with no clear direction that I can find online. The problem got so bad though that my options were to fix it immediately, stop driving the car, or find a temporary fix without causing permanent damage and buy more time to decide what to do longer term. Purchasing an S8 is at the top of that list, and I opted for buying some time.
A few of you have asked on this forum if there's any way to disable the mechanism so that the screen stays open. I haven't seen anyone else confirm that this is possible - So I'm confirming just that. It is possible and should take about 20 minutes. This is on my 06 A8L.
You'll need a flashlight, T10 Torx driver, electrical tape or cap, wire cutting implement of some sort, and that's about it. You will need to cut a wire.
Once the gear has stripped enough that the screen gets stuck somewhere between up and down, try to get it stuck about here:
Then take a look at the back of the screen; you should see two T10 Torx screws that I removed right before I took this picture of their holes. Take them out:
Now press the button on the dash or turn on the car to flip the screen all the way up via the motorized mechanism. Now you can lift the screen itself almost straight up and off of its carrier. Don't lose the two square washers that were attached to the Torx screws and will fall off when you remove the screen. There is one wiring harness going to the screen itself. Flip up the metal door on the bottom rear of the screen and unclip the wiring harness:
Now you're left with the mount for the screen in the full open position, but the motor is still hooked up and will still drive the screen lift mechanism when you start/stop the car:
There are two wires going to the mechanism's motor, a yellow and a blue one. Cut one, (I picked blue) but not too close to either end, because when this all ultimately gets taken apart to complete the permanent fix you will need to reattach this wire. Cap or tape it off so that you don't short anything out. Note that there's a wiring harness at the other end of the motor wires but it's buried so far into the dash that I couldn't even get close to disconnecting it and so had to make the cut:
You're almost there. Just reattach the wiring harness to the screen and drop it back onto its mount. Friction should hold it in place fairly well, but you can probably wrangle one of those Torx screws back in if you're planning on letting this go for longer than I plan to:
Hopefully this helps someone; I've been able to accomplish a lot based on info provided on this forum and felt I owed a bit something back!
-Mike
I've had the dreaded MMI stripped gear problem for the past month or so, where every time I start and stop the car the MMI screen produces the most dreadful cracking/grinding sound, and the screen eventually lost the will to raise and lower on its own - I now need to help it every time. I've almost lost a finger in there more than once, and my manual assistance still doesn't stop the unbelievable noise. It's loud and passengers are frightened/appalled. I haven't had time to bring the car in for service, and haven't decided whether I want to pay for the full mechanism or try to just replace the gear with an eBay one; the first option is extremely expensive, and the second incredibly time consuming with no clear direction that I can find online. The problem got so bad though that my options were to fix it immediately, stop driving the car, or find a temporary fix without causing permanent damage and buy more time to decide what to do longer term. Purchasing an S8 is at the top of that list, and I opted for buying some time.
A few of you have asked on this forum if there's any way to disable the mechanism so that the screen stays open. I haven't seen anyone else confirm that this is possible - So I'm confirming just that. It is possible and should take about 20 minutes. This is on my 06 A8L.
You'll need a flashlight, T10 Torx driver, electrical tape or cap, wire cutting implement of some sort, and that's about it. You will need to cut a wire.
Once the gear has stripped enough that the screen gets stuck somewhere between up and down, try to get it stuck about here:
Then take a look at the back of the screen; you should see two T10 Torx screws that I removed right before I took this picture of their holes. Take them out:
Now press the button on the dash or turn on the car to flip the screen all the way up via the motorized mechanism. Now you can lift the screen itself almost straight up and off of its carrier. Don't lose the two square washers that were attached to the Torx screws and will fall off when you remove the screen. There is one wiring harness going to the screen itself. Flip up the metal door on the bottom rear of the screen and unclip the wiring harness:
Now you're left with the mount for the screen in the full open position, but the motor is still hooked up and will still drive the screen lift mechanism when you start/stop the car:
There are two wires going to the mechanism's motor, a yellow and a blue one. Cut one, (I picked blue) but not too close to either end, because when this all ultimately gets taken apart to complete the permanent fix you will need to reattach this wire. Cap or tape it off so that you don't short anything out. Note that there's a wiring harness at the other end of the motor wires but it's buried so far into the dash that I couldn't even get close to disconnecting it and so had to make the cut:
You're almost there. Just reattach the wiring harness to the screen and drop it back onto its mount. Friction should hold it in place fairly well, but you can probably wrangle one of those Torx screws back in if you're planning on letting this go for longer than I plan to:
Hopefully this helps someone; I've been able to accomplish a lot based on info provided on this forum and felt I owed a bit something back!
-Mike
05-04-2011, 07:35 PM
#3
AudiWorld Super User
Yes, thank you very much! I had to have the whole assembly replaced once before. Now I am always leery to open it when I go on short trips. I wish there was a way to keep it open at all times, as if I could just do what the OP did, but just unplug some wire to keep it open. Wish somewhere in the VAG control you could change it. I'm sure there isn't but I would love it if there was!
05-04-2011, 08:43 PM
#5
AudiWorld Super User
Excellent idea mishar!
If/when I have to do this I'd consider adding a switch discretely to the panel.
Perhaps with backend 'logic' so it could be a soft switch or reuse the MMI eject button.
If/when I have to do this I'd consider adding a switch discretely to the panel.
Perhaps with backend 'logic' so it could be a soft switch or reuse the MMI eject button.
05-04-2011, 10:41 PM
#6
AudiWorld Super User
Or somehow you could just use the button that is already programmed to open it. Just somehow code it to not open automatically, or to stay in the position it is in unless that button is pressed i.e. turning off the car does not close the screen as well.
05-15-2011, 11:26 AM
#7
AudiWorld Super User
Can you update us on how it is working for you? I have two questions as well.
The wire you cut isn't part of the car electronics correct, it is part of the gear nav assembly that would be otherwise replaced to fix this issue correct? (Given you don't just fix the gear)
The nav screen doesn't jiggle in place at all does it? I'm guessing the screen is just locked in place with the gear in the most upright position.
The wire you cut isn't part of the car electronics correct, it is part of the gear nav assembly that would be otherwise replaced to fix this issue correct? (Given you don't just fix the gear)
The nav screen doesn't jiggle in place at all does it? I'm guessing the screen is just locked in place with the gear in the most upright position.
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05-15-2011, 02:49 PM
#9
AudiWorld Super User
"All this" comes if your gear is broken whatever you decide. You can save $400 and just cut it opened, $300 and buy gears only, or $0, buy OEM part and wait for it to break again. Work is fairly the same.
I like the idea of introducing a switch in that circuit and keep it opened, or more likely closed at all times. I hate that retracting screen at the first place.
I like the idea of introducing a switch in that circuit and keep it opened, or more likely closed at all times. I hate that retracting screen at the first place.