Gilly, I emailed about this problem some time ago, and it is getting worse! My 2000 ML320 MCS unit's buttons just quit working while driving. This has happened about every 60 days for maybe 6-8 months. But, yesterday it happened 3 times in 1 day! I have been successful just pulling the #10 & #21 fuses and replacing them (and re-entering the security code). The last time (yesterday) after replacing the fuses, the buttons began to work again without being prompted for the security code.
My truck is out of warrranty (and nearly out of the 1yr extended warranty). The dealer says its not covered. My first complaint to them was when the truck was about 2 yrs old, but it fixed itself after re-starting the engine.
Do you have a service bulletin with info? Can the unit be fixed or must it be replaced? (Do you know what the cost will be?)

Thanks!

Not familiar with "buttons stop working" complaint, only the "black screen" complaint. Ultimately I'd say it will need a new MCS. A reman unit is available, the one that I know fixes the "black screen" problem is part number 163 820 21 86 90, this is for a reman unit, they'll need your junky one in exchange. This part number is only for 2000 model year. For 2001 models it is part 163 820 24 86 90.

Gilly

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Gilly, thanks for the part numbers.
Is anyone else having MCS problems? Anyone have to replace the unit? What did it cost?
Thanks.