1995 W124 E420...the convenience feature on my vehicle is not operating consistently...windows, locks, and sunroof operation are all normal/no problems...however, sometimes, when I press the window down next to the selector for the front window to roll all the way down by itself...it does not come down automatically all by itself...also, when I hold the key down so the sunroof/windows close, it sometimes does not work...is there a module that controls this operation/function? is there a fuse I can reset? It works sometimes, then stops working other times...I've used the system pretty often on my vehicle and it has only been acting up lately... Thank you for any insight into the problem...

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1995 black pearl/black Mercedes-Benz E420 :