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Rear defrost problem - and not the normal issue!

2262 Views 13 Replies 6 Participants Last post by  12 lt
Hi everyone - got a 2012 LT with a rear defroster that's inoperative. Here's what's been done so far:

1. After buying car, noticed clip wasn't attached to glass on passenger side. Also noticed the black plastic end holding the part of wire that attaches to clip was slightly melted.

2. Reattached clip using Permatex kit - followed directions precisely, waited 24 hours, reattached wire to clip, turned on defrost, clip popped off in about 5 seconds.

3. Took car to dealer. They replaced clip and replaced end on the wire that was melted. Did not reattach wire to the clip, so I did that. Once reattached, pressed button to turn on, clip popped off again in about 5 seconds.

4. Took back to dealer, they tried again. Now the button can be pressed and clip doesn't come off glass, but does not defrost at all.

5. Figured this was now the issue with the wire harness near the passenger footwell. Opened it up, there was minor darkening of the plastic, but not terrible. Still did the bypass with a piece of 12 ga wire anyway.

6. Checked relay and fuse - both good.

7. Checked voltage at back window and across all grids - all good.

8. Made a video:

Any ideas?! Interestingly, after pushing the clip in to the grid to make this video, it popped off the glass again. I'm wondering if the defroster grid isn't shot and the whole window needs replacing... I'm really out of ideas at this point.

Also - mods - I tried posting this as a follow-up to a recent defroster thread... no dice, so I'm not sure what I did wrong. Hope this one works! Thanks, all.
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It seems like you have voltage to the tabs based on the video. I would take the wires off both tabs, and measure the resistance between the tabs with a multimeter. This will be testing the continuity of the grid/tabs to see if there is a break somewhere. I am betting that you permatex repair is not making good contact with the grid. If you do the multimeter testing, and you have an open, or very high resistance (it should be less than 2 ohms I believe), you can try checking continuity (resistance) between the non-repaired tab, and the grid right beside your repaired tab. If it shows a low resistance then you know your repaired tab isn't making contact with the grid.

There was another person on here who tried using the permatex repair with similiar results as you. While it is somewhat conductive, it still added extra resistance which prevent his window from heating up.
I used this kit to repair mine that had broken off
Has been working great for 3 winters.
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Just ordered the Frost Fighter - new tab and attachment kit. Figure what's another $50 in to this. :) I am crossing my fingers for success... you don't realize how much rear defrost is taken for granted until you don't have rear defrost anymore! Thanks for the input.
Good luck. This slant of the window and rear deck make this not very much fun from what I remember. Please report back how it goes.
Snowball test was successful in garage this morning. The result is after about 30 seconds of the defrost being on. Very pleased.
Glad it worked out for you. I try to steer everyone towards the frost fighter because it seems to work much better than the permatex. The additional cost might scare some off, but it seems to be worth it.
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