Rear Windows Comes Down on Their Own!

Mine had this happen and the switches need to be recalibrated. These are the instructions I think I used:

With ignition switch in the “ON” position, do the following:

1. Push down and hold the driver’s door power window switch to completely open the window.
2. Pull and hold up the driver’s door power window switch until the window closes.

Continue holding the switch for approximately one second until the switch changes from blinking to a constant illumination.
3. Check for proper operation of the “one–touch open and close” function by fully pushing the switch briefly to the “DOWN” and “UP” positions.

At this time the power window switch for the passenger’s door window should be blinking.
4. Push down and hold the passenger’s door power window switch to completely open the window.
5. Pull and hold up the passenger’s door power window switch until the window closes.
Continue holding the switch for approximately one second until the switch changes
from blinking to a constant illumination.
6. Check for proper operation of the “one–touch open and close” function by fully pushing the switch briefly to the “DOWN” and “UP” positions.

Do this with both back window switches on the driver's door

SM-G991U ?

 

Spray some silicon in the rubber channels the glass travels in. Car window motors have sensors that reverse direction if they sense an obstruction to protect people from getting injured so any additional friction on how those windows move will cause this.

 

If that's happening "when they reach to the top", then the "obstruction" they are sensing is the top of the door.

The Prius window regulators have to learn where the top is, so when they sense that obstruction they think "well, I'm all the way up, so that's the obstruction I'm supposed to hit." If their memory of that position gets lost, then they will behave as the OP described, where they hit the top and then safety reverse.

The relearning procedure is something like what was described in post #2 (but it's funny, the way I remember it, you have to do it from each window's local switch, not from the driver's master switch). The procedure's in the repair manual, of course, so if it doesn't clear up from the post #2 steps, it might be time to crack the book and make sure the details are right.

 

ChapmanF might be right about doing it at each door. It's been a few years since I had to do it and this was a post I found that is similar at what I had to do. I do think it's in the manual if you have it or you can download it from Toyota's website

SM-T970 ?

 

Yes, that's exactly what's happening... Usually it's caused by a combination of 1) a person's hand grabbing the top of the door when getting in and out of the car, which slides the weather stripping in it's channel so much that the corner of the glass no longer has a corner to go into, and 2) dirt and grime building up in the weather stripping channel when friction between glass and weather stripping is at its maximum, which is when window is near all the way up.

I've seen this problem more than once on driver's side front door, but never in back doors, but I guess if you got kids...

 

It happens in a perfectly clean, unmolested, factory new door, any time the regulator hasn't yet learned where the top is.

The regulator is programmed to reverse whenever anything stops the glass.

There is a metal bar and track across the top of the door. It's built that way. It'll stop the glass, every time.

It's still there even after cleaning and spraying silicone.

The regulator's programming includes one exception to the always-reverse-if-stopped rule. The exception is, once it has learned where "all the way up" is, it doesn't reverse when it gets stopped at "all the way up".

If its memory gets wiped, it will go back to reversing when the top of the frame stops it, until you teach it that's where "all the way up" is again.