Just happened to me today, hot weather driving with my dog in the cargo area. Tried rolling the rear hatch window down, made usual motor noise but glass didn't move. Few seconds later the whole rear glass dropped inside the hatch.
Dog gave me the WTF look LOL
Pulled over to inspect. Liftgate Window regulator mounting tabs on both ends rusted and corroded through, and broke off clean. Window still in one piece.
I was able push the window back into fully closed position, and used gorilla tape all around the glass to hold it in place for now.
Window motor still works.
I would add lubricating these parts to your regular maintenance routine. Once a year should do it.
New part ordered and on the way.
The joys of owning a high mileage vehicle never ends.
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2004 4Runner Limited V6 4WD ***SOLD***
385,000 Km
Titanium Metallic
Vehicles: '21 Highlander XSE V6 AWD | '21 Acura RDX SH-AWD Tech | '03 Honda CBR600F4i