Water In Back Seat

the water is coming up from under the seat and wetting the seat top?
is the floor wet?

 

There's no sources of water inside the cabin, under the rear seat. The battery pack is back there.

Take a gallon of water and pour it along the top edge of the rear window and see if it leaks in from there.

 

Has anyone found the fix for this? I have the same issue. There is no visible leak anywhere and when it rains, especially for a while, the passenger side backseat becomes wet. You can see the water marks in white in the photo.

 

I have a couple of ideas. I don't know however if this applies to the 2016-2017 model year. These are thoughts from observing power window functions in my 2021 model. If all four of your windows have the auto up/down feature, you may notice when using auto up that the window will go all the way up and then it will relax back down a little ways. This might be something engineered into the system for an ideal compression of the weather stripping to make a seal and yet not be very tight in the fitment all the way around the window. This would allow for some amount of flex in the door without straining the power window mechanism. The "relax" might be a little too much, allowing a space to form at the top of the window which then allows rainwater to enter. There might also be a preference for one side only to leak based on the direction from which the rain is coming. I remember in the Gen III power window that had an auto up return you had to calibrate it after disconnecting the 12V by rolling it down a ways then full up and hold the switch up until it "clicked". The Gen IV windows aren't in need of any calibration by the user after a 12V battery disconnect, so Toyota must have figured that out. I guess the test would be to operate the window on the leaking side, and then after see if the space between the weather strip and window glass is big enough to allow leakage. If you discover a misalignment or improper seal you might need to take it to a dealer service department.

 

I have an addendum to the above. There are some initialization instructions for the power windows toward the back of the Owners Manual. For my year vehicle they start on pg. 219.