There are two mcs units one in master switch as well as passenger side front door. You could check the fuses I mentioned which in the diagram points them out. I kind of doubt it's the relay however due to the front windows working. However you can try to do a reset and that may make the rear windows work. See pics. It's important in step 4 to do within 5 seconds of each other.
Images (Click to enlarge)
Thursday, March 12th, 2015 AT 8:14 AM