1992 Ford Taurus rear windows

Well looking over the wiring diagram I can find only one of two things if it isn't the motors. They are the master switch on the drivers door or the switches on the rear doors. I would more so suspect the master switch as this is what sends the power to the rear switches.

The power window circuit is very basic really. So what I would do is pull the drivers side switch (master switch) and with a test light check the blue wire with the black stripe should have power (this is power in). Then check the red wire with the light blue stripe, this goes to the left rear window. So what you do here is hook up a test light and push the up should get power, if no power bad switch. If you have power there then check the yellow wire with the blue stripe (this is the down to the left rear window). So you hook up you test light to that wire and then push the down to that window if now power bad switch. You do this with the harness pluged in you are testing to see if power is going through the switch. You also have to do this with the key in acc. Possition or key on engine off which ever way makes the front window work. Let me know what you find and we will take it from there.