Why aren't my back windows don't open?

Have you checked your fuse yet? the Owners manual says Interior fuse box, passenger side, fuse 7 (L window), 16 (R window). Both are 7.5A ratings. Here is the fix for the actuators as well. Hope this helps. If not give a bit more info like any noise coming from your windows, any clicking grinding etc. Good Luck

UPDATE just got this info I wanted to add to the answer.

"Check the power window relay and check the wiring harness to it. Sounds like you have some intermittent contact. Hav you tired to reset your windows? "Resetting the power window control unit is required after performing the following procedures

• Disconnecting the battery.

• Removing the No. 79 (20A) fuse in the under-hood subfuse box.

• Disconnecting the 18P connector from the power window control unit.

• Removing the window regulator, glass or glass run channel.

• Disconnecting the driver’s door wire harness.

1. Turn the ignition switch off, then back ON (II).

2. Move the driver’s window all the way down by holding the driver’s switch to the AUTO DOWN position; when the

window reaches the bottom, hold the driver’s window switch in the AUTO DOWN position for 2 seconds.

3. Move the driver’s window all the way up without stopping by holding the driver’s switch to the AUTO UP position;

when the window reaches the top, hold the driver’s window switch in the AUTO UP position for 2 seconds.

If the window does not work in AUTO, reset the power window control unit according to the above procedures again. " great information from here. Hope this helps.