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So, the rear defroster on my 2008 crapped out this winter. Can't tell you how much I appreciated it until it was gone lol.

But anyway, I will be attempting this fix this weekend. I checked the relays and stuff just to try and make sure (I don't have a garage, so I checked what was easiest to do out in the 15 degree wet snow), so I'm pretty sure when I pull open the passenger side kick plate this weekend I'll find what the issue is.

So, for those of us who would love images to guide them along or are visual learners or are just a little unsure (like me), here is a YouTube video explaining how to do the fix pretty well.


I hope this helps! With the write up and comments on this thread plus the video I'm sure even a caveman like me can fix it. Good luck to all attempting this!
 

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A Packard 56 connector will carry 48Amps and the rear defroster grid is fused for 40Amps.
You can get single position Packard 56 connectors.

2977253 Single Male Terminal Packard 56 connector housing
2984528 Single Female Terminal Packard 56 connector housing
2971859 12Ga Female Packard 56 terminal
2989877 12Ga Male Packard 56 terminal

Spray them with battery terminal protectant to halt corrosion.
 
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I fixed mine the same way a few years back. It was still working at the time but it was already discoloring and was a matter if time. No issues since either. IMO I think that the surface area of the connector used was too small to handle that amperage, however this may have been previously mentioned. The video you posted T will help others I'm sure.
 

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I fixed mine the same way a few years back. It was still working at the time but it was already discoloring and was a matter if time. No issues since either. IMO I think that the surface area of the connector used was too small to handle that amperage, however this may have been previously mentioned. The video you posted T will help others I'm sure.
They sure are. That kick panel connector is a mix of Metripak 150 & Metripak 280 terminals.
The 40A defroster is running through one of the Metripak 280 terminals. Metripak 280 terminals are rated for 30A MAX... even 35A continuous current will make it nice and crispy.
 
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Thank you to all who have posted about this issue. I have a 2014 Chevrolet Impala Limited Police cruiser. Same issue. I tried getting this information a couple of months back, but no luck. Happened to get an email with this information today. Now I’m going to call GM and also going to try and fix this issue. Thank you again.
 

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I can't help wondering how this happened. GM is no slouch company - they have some truly impressive engineering accomplishments. But I'm shaking my head how something like this slips thru. This pre-dates the meltdown, so it can't be blamed on all the scrambling that was going on in the wake of that. IOW, it's hard to excuse this.

Was it spec'd in by some new-grad who didn't know the load current going to the defroster? Did no one review this before they put that connector in the spec? Was the connector vendor aware of the application? (He would be aware of how much current those pins could handle, and wouldn't want the headache of dealing with the failures, even if it's not the connector's fault.) How did this connector perform in product testing? Surely the test drivers turned on the defroster a few times during qualification testing. And why was the connector never upgraded in the course of production once all the failures became evident?

My experience is that their engineering is constantly running qualifications. Constantly. If you are a supplier and want to make a product change, they will re-qual your widget as part of their normal routine. All the methods and procedures are well known and long established there. So getting a better connector engineered into that wiring harness was something they can do without great difficulty.

That it was under-spec'd is bad enough. But that it continued is unbelievable.

All I can figure is it's one of those US-Canadian things. Somebody was asking for metric amperes but the connector was spec'd for SAE amperes :)

Doug

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I can't help wondering how this happened. GM is no slouch company - they have some truly impressive engineering accomplishments. But I'm shaking my head how something like this slips thru. This pre-dates the meltdown, so it can't be blamed on all the scrambling that was going on in the wake of that. IOW, it's hard to excuse this.

Was it spec'd in by some new-grad who didn't know the load current going to the defroster? Did no one review this before they put that connector in the spec? Was the connector vendor aware of the application? (He would be aware of how much current those pins could handle, and wouldn't want the headache of dealing with the failures, even if it's not the connector's fault.) How did this connector perform in product testing? Surely the test drivers turned on the defroster a few times during qualification testing. And why was the connector never upgraded in the course of production once all the failures became evident?

My experience is that their engineering is constantly running qualifications. Constantly. If you are a supplier and want to make a product change, they will re-qual your widget as part of their normal routine. All the methods and procedures are well known and long established there. So getting a better connector engineered into that wiring harness was something they can do without great difficulty.

That it was under-spec'd is bad enough. But that it continued is unbelievable.

All I can figure is it's one of those US-Canadian things. Somebody was asking for metric amperes but the connector was spec'd for SAE amperes :)

Doug

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Metric Amperes and SAE Amperes. :lol::lol:

They have an undersize connector speced by an Intern or Jr engineer and it stayed that way for a decade.:WTF::WTF::WTF:
The new normal in the manufacturing world. Sidestepping responsibility for product problems that aren't recall level or PR disaster issues even if they're life threatening or could cause serious damage to the vehicle. This one won't burn the car down but it could possibly cause a vehicle owner to sell and buy another vehicle so it's a win for the bean counters.
The ignition switch issues and several other life threatening problems show that the a-moral bean counters decided that dollars are more important than lives... paying lawsuits are cheaper than repairing life threatening faults in most cases. I wouldn't want to be in their shoes when dad asks "Why?" on Judgement day.
 

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I was just cruising the forums and saw this post. The defroster on my 2010 LT wasn't working so I figured lets take a look. Thanks to this thread I'm back in operation. What the hell was GM thinking with that design??
 

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2013 LTZ here, performed the fix (minus the fuse, since the circuit is fused under the hood) 3-4 years ago. Worked fine for a period of time, but issue reappeared. Tested relay, it was good (coil & contacts). Underhood fuse was good. Voltage check at fuse block was good. I am an electrician by trade and I did note that wire size is way smaller than should be for being fused at 40A. After all testing, unplugging/plugging relay, felt I wasn't getting anywhere. A couple days later the wife thanked me for fixing it....okay....you're welcome, but I didn't do anything.
After time,(I can't remember how long, but still in the same season) it stopped working. Again. This time investigating at the underhood fuse block turned up overheating/melting at terminals where relay plugs in. No charring or the like, just softened plastic. Turns out the overheating/softened plastic was causing the terminals to move/shift enough to prevent good contact with tabs on relay. My fix was to use pliers and put a slight twist on the relay tabs, just the ones that carry the current to the back glass. Reinserted relay and that took care of the issue.
Now as I type this, 28/11/2021, the car sits out in the driveway with a non-functional defroster....AGAIN. I'm going to perform the twist again, hoping that it'll get through the season, but then the whole circuit is getting rewired.
 
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