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MMI 3G change to 3G+ and weird sound problem (A1 2011)

tournevis May 9, 2020

  1. tournevis

    tournevis Registered User

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    Hi All,

    I would normally introduce myself as an Audi A1 expert, however obviously I’m not a total expert since I badly need help in an electronics matter.


    I’ve already searched the net, however swapping of MMI 3G with 3G+ (Plus) is so rare that no trace can be seen of such a problem.


    So, I have an A1 122hp DSG 2011, it comes with MMI 3G (double SD slot and nav) and Bose.


    I wanted to change the onboard MMI 3G with MMI 3G+ version.

    I’ve bought the MMI 3G+ unit (same year), a new HD screen, a DAB radio and an adaptation harness. After fitting I went to Audi dealership to remove the Component Protection (CP).

    The devices not being sold by them, Mister Audi technician warned me that he can’t assume any responsibility if it doesn’t work out well. At the beginning he even didn’t want to do it. I’ve insisted, telling that “best effort” will be enough for me.

    The CP was removed, and everything seemed to work perfectly.


    However, I quickly found that there is a weird problem with the sound.

    My car has the sound on only randomly 1 of 5 starts. When not, there is no sign whatsoever, no error no nothing. Just no sound. The sound knob is still showing that the sound is on, but nothing can be heard.


    Since almost a year, I could not find a correlation between the randomness of having the sound on at start and some other parameter.

    However, since the beginning I’ve noticed that if I unplug then plug back any optic fiber connector (the MOST wiring), after 1 or 2 or 3 (randomly) trials, the sound comes back on. It will stay on till the car stop. Such optic fiber connectors can be found in the Gateway (closest one to the driver), at the MMI unit rear or in the boot – the Bose amplifier and radio unit.

    No matter when it randomly starts – right at the beginning or after unplugging several times a Most connector - once on, the sound is working fine till the car is stopped and onboard electronics enters standby.


    My own further analysis:

    1. the MMI 3G+ unit is working well. I was suspecting the unit thus I have changed it with a second one (CP removal redone). Nothing changed, same sound problem.

    2. I tried without the radio (combo FM/DAB) unit connected (electrically as well as optic fiber): nothing changed, same sound problem.

    3. I updated the MMI 3G+ unit firmware with the latest version. Nothing changed, same sound problem.

    4. A Vagcom check will show the classic “incompatible version” message following my third-party firmware upgrade with maps upgrade. Sometimes it will show “inconsistent signal” for antennas. Not correlated with the sound working or not.

    5. I tried to solve the “incompatible version” message by doing the popular coding trick available for MMI 3G. It didn’t work, perhaps because my MMI is 3G+ and I have now a different error message. However, nothing changed in the randomness of the sound.

    6. I cannot go back to the Audi dealership because they are not able to check such errors and even less repairing them. They only follow their software instructions and the software was telling that everything is Ok (they showed me that).

    7. A third party VAG electronics specialist told me that he personally suspects the SVM (Software Version Management – some kind of micro firmware) not being good, however he cannot help me.


    So, what do you think it is?

    Remember that optical connector unplug/replug manual action that ultimately activates the sound. Probably the clue is hiding there.

    Any help will be much appreciated.
     
    Last edited: May 9, 2020

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