TK - yes, similar but the older generation MB's do not allow normal window operation unless the key is "On", regardless of door open/closed. My problem is that the windows/seats do not function while cruising down the road. The power seats work fine when I open the door w/out the key in the ignition, so wherevever the fault exists, it is being bypassed with the door open/ignition off signal. And I am not even sure the power seats/windows problems are related - just hopeful to make it a simple fix.
Ken - I think you are on the right track. Is there a simple way to test/inspect these diodes. I have easy access to several in the back of the fuse box, and am not sure how to determine if one is bad. My best course of action would be simple replacement - if I knew what I was looking for.