To preface, my convertible top went out a while ago. (Just refilled with hydraulic fluid and works now). Anyways, my quarter windows still worked for a while after the convertible went out. I recently searched why my quarter windows didn’t work and a lot of the issues seemed to relate to the top, so I fixed the top. That of course didn’t fix the problem. Does anyone know the answer to this, is it a fuse, maybe a wire, or would you think it’s the switch panel. It’s just odd they both went out at the same time

 

Not overly familiar with your model years. My S550 has a single control for the back windows. In any event, if not too difficult to pull the switch(es) out of the door panel and check for power into the switch (if not, check the fuse). If you have power there, check to make sure the switch is passing power. If the switch is passing power you then can pull the interior panels and make sure you’re seeing power at the motors. Since neither are working, I suspect you’ll find the problem closer to the switch or in the body control module, if there is one in your car.