The rear window to my 2004 Prius was replaced two years ago with an after market window. Recently the defroster stopped working and I had it replaced with an OEM window. Now the defroster works but only every 2-3 lines work. In other words the bottom and top few and a few lines in the middle do not work. I also noticed the smaller bottom rear window defroster does not work at all. I took it back to the auto glass shop that did the repair and he did not seem to know what was wrong but told me that the problem with the two windows is likely unrelated to each other. Two photos attached showing the new OEM replacement window. Can someone help me troubleshoot this? Thanks much.
I agree with the glass shop guy that there probably isn't a single issue causing both problems. Maybe the lower window just hasn't been reconnected. It's not too hard to pull off the inside hatch trim and just look. The big window should only have two connections (for + and ground); if there are some traces that aren't heating while others are, probably the ones that aren't have been scratched through somewhere. That is certainly disappointing in a brand new window (whether it arrived that way, or got scratched in handling during installation). There is, anyway, a handy conductive paint you can use to repair breaks in defogger traces. You just have to find the break first, which is easy to do with a voltmeter. If you run a voltmeter probe along a working trace (other probe connected to ground), you'll see a steady rise from 0 volts at the ground end of the window up to 12-ish at the + end. Do the same thing on a scratched-through trace and you'll read 0 everywhere on the ground side of the scratch, and 12-ish everywhere on the other side. (It's trickier if there ever happen to be more than one scratch in the same trace.) Then, once you've found the scratches, turn the power off, paint over them with the conductive paint, wait the prescribed amount of time, and drive away with your working defogger. It's common to lay down some tape on both sides of the trace before painting, so the job will look tidy when you take up the tape. If it was damaged during installation, as a matter of principle, you might want the installers to fix it for you, but if you put simplicity over principle, it's pretty easy to just fix and be done with it. -Chap
Those are absolutely damaged. That’s why they don’t work. There is no other reason. The window guy knows what’s wrong. Either he or you scratched them and he does not want to pay for a new window to replace it.
Maybe some window installers are capable of doing the repair like @ChapmanF describes. It would seem like a good business practice, to test the defogger after an install, and do pro repairs if there's any such breaks. As opposed to battling with customers, maybe doing yet another complete replacement.
A thermal imager, by the way, makes a kick nice person way of checking window and mirror defoggers, heated seats, etc. ... the heat element pattern shows right up. I actually wrote nice person, knowing the forum software was going to do it anyway. Whose idea was that, I wonder?
