400E Intermittent sun roof and window problem
 

Hello: I am experiencing a problem where the sun roof and windows on my 92 400E only work intermittently. Can anyone tell me if the problem is likely in the convenience control unit, and if so, where that is and how to troubleshoot it? I have checked the unit under the back seat, and it seems to be working as when the windows are or are not working I can hear the under the seat unit click when I press one of the window buttons.

Thank you very much for any help in this matter.

Thos43