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Discussion Starter #1
Finally looked into why the defroster wasn't working (hasn't really worked more than 1 or 2 times in the 7 years i've owned the car). was the typical wiring short in the harness by the passenger right foot. the plug was burned badly in the quadrant the defroster wires enter. 3 dollar inline fuse and 10 minutes to fix the issue....just amazing they never put a fuse in for the rear defroster....

now the question i have is, after letting the rear defroster run for about 5-10 minutes the rear window was hot enough to cause me to remove my hand because it was "hot". anyone else noticing their rear window getting this hot when running the defroster? just curious, it didn't pop the 30 amp fuse and i turned it off before letting it get any warmer, was kind of afraid to see what happened if it didn't lol.
 

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There is a fuse for the rear defogger.

The fuse isnt the issue causing melted connectors though. The problem isnt even excessive electrical current. Its restricted electrical current flow, The terminals buildup up resistance, the resistance actually lowers the circuit amperage but it causes heat buildup in the connector. the connectors melt due to heat build up from excessive resistance. This is the same reason headlight sockets melt. (and blower resistors, and cooling fans, and every other melted connector on a GM vehicle.) Dielectric lubricant is the solution (or larger surface area, more durable, lower resistance terminals....)
 

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Yeah, actually, if I remember correctly, adding an in-line fuse was NOT a good idea (if you read through that entire "rear defroster fix" thread, you'll see where that was eventually pointed out. Since there is already a fuse, the "extra" fuse caused issues (I believe).

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Discussion Starter #4
ok i re-read the article and it appears just a jumper wire past the plug is the fix. now until i can get around to fixing my fix, i'll just pull the fuse i installed so it doesn't cause a greater issue.
 

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Youre not likely to cause a greater issue. the circuit is still protected by the factory fuse. So as long as your replacement wiring/fuse holder has the same ampacity rating your safe.

The issue is that putting in a fused jumper wire to bypass the connector with the burnt terminals doesnt actually solve anything unless the jumper you put in has lower resistance than the failed terminals, and greater resistance to "fretting" which is the motion induced resistance problem that causes the burning in the first place. I wouldnt stress over it too much if you used quality fuse holder.wiring and made a good connection :)
 

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Here is a link to the original repair write-up:

[ame]http://www.impalaforums.com/showthread.php?t=251292[/ame]

The folks that used an in-line fuse had heat-related issues - and one even caught on fire! :) It was mentioned that the additional in-line fuse increased resistance, which caused the extra heat. No sure if the issues are due to low-quality in-line fuses, in-line fuses with incorrect "specs" for the job or some other issue, but I wouldn't risk using one - it sounds like it can only cause potential issues - and certainly not help at all.

In fact, I'm going to add a "moderator note" to the OP in that thread so that people know not to use an in-line fuse - just in case they don't read through the thread and stop after the first post...

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Thanks jtrosky, Ill look at that and see what was recommended and how it compares to actual best practices.
 

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Where is the fuse located? I had the dealer fix my defogger years ago because of the ongoing problem Chevy won't talk about. Now it stopped working again. I'd like to try the cheapest option first but don't see where the fuse is located.
 

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Where is the fuse located? I had the dealer fix my defogger years ago because of the ongoing problem Chevy won't talk about. Now it stopped working again. I'd like to try the cheapest option first but don't see where the fuse is located.
The fuse is located in the Under hood fuse block and is listed as BATT 3 and is a 40 amp fuse.

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It draws a huge amount of current, so the thing is to use heavy enough gage wire to not restrict the current, which then causes heat and failure/fire.

I never had this problem in the '10, because the grid itself had broken from sun exposure/cleaning action.

I'd check for power at the connector to the grid to see if the connector at the footwell is still good before taking anything apart. If there is current at the connector at the grid, when the rear defog switch is activated, then the issue is the grid itself.

I'd considered fixing my grid, but got fixated on just flipping it to get the Limited, so I didn't bother to fix it, and traded it in needing the repair.

The grid can be repaired with a special conductive paint you apply like a fingernail polish paint at the broken element location(s).

This is a generic fix for any brand's rear defroster grid, vids on YouTube explain it well.
 
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