I bought my 2017 Yaris iA in March of this year, so this will be the first winter it's been through. I noticed recently that, when I need to defrost the rear window, the bottom 3/4 or so (with just the horizontal wires in the glass) works fine. But the upper part, which has a grid of both vertical and horizontal wires, does nothing at all, like it's not connected. Is anyone else experiencing this problem? I guess it's not critical, but it IS annoying, and I like to see out of my windows as much as I can. I'm due to take it in for service shortly, and I wonder if I should bring this up. It's still covered under the warranty, of course.