Passenger backseat window

Welcome to 2CarPros. How has it broken? The glass itself shatters or the regulator stops working?

It just shattered. It's a half window. No electrical system in it.

Okay, the common reasons for glass like that to fail is that there is something hitting it on the edge. Tempered glass is tough if you hit it flat, however any hard stress point on the face or a small scratch or chip in either place will cause it to fail. With it installed it would be hard to find but if it was removed you can look at the area the glass sets in. You are looking for anything that might touch or puts any pressure or twist on the glass. The reason is that heat/cold cause expansion and contraction of the metal and the glass. Something that could look fine at 70 degrees might cause a problem at 90 degrees. I've seen rust spots, screw points, rivets, leftover glass from an old broken window, metal slivers and even rough spot welds cause glass to fail. Was there anything in common with the glass breaking? Like it was very hot/cold or you were on a rough road or hit a big bump?