Rear defroster not working...(Update: Pulled fuse...WTF???!)

[GTPGuy82]

Does anyone know if the fuse could be my problem? I turn the rear defroster on, the yellow light comes on, but the rear window never clears up. I know there's a fuse for the defroster, but it's not a typical fuse I don't think. It's something bigger, like a cube-type thing. But if the fuse blew, would the light on the dash still come on when I switch it on?

This sucks, especially in the coupe.

[grfnkl]

Normally the larger cube like thing is the relay and they normally have a standard fuse as well. I could be wrong on this though. Check to make sure that the wires didn't get disconnected at the window itself.

[ahuhn]

fuse is in the rear fuse block its a 30 amp fuse(number 23) so it may look like a cube with a clear plastic window on top. if you look through th e window you should be able to see if its intact or not

and yes the indicator will light up with the fuse blown

[WoodburyMan]

I will say 75% sure it's the fuse. In my Sunfire, in the 3+ years I had it the fuse for the defogger went out at some point during the winter when I used it a lot for some reason.

[grfnkl]

I only suggested checking the back wires, since my G/a kept frying the connection right off the window and I could never get it back on and get it to stay... and it all happened without warning one day. and I didn't feel like paying $300.00+ to getting it fixed.... i just dealt without it.

[GTPGuy82]

ok thanks. hopefully it's the fuse. I'll take a look back there later or tomorrow.

[e2helper]

One thing I would suggest is because there is also a relay in rear electrical center as well is that you operate the Rear Defogger ON/OFF if you hear the relay clicking and off - if too noisy and you have a helper they can stick their head in the trunk or even put their finger on it while you activate.

This will tell you if the issue is with operating the relay or power from relay to rear grid (which are different issues).

Second - (and your profile might tell me this) do you have the manual or automatic HVAC system. There is a slightly different way that these 2 systems work as far as how the rear defogger is activated. EDIT: OK since your name is GTP... I will assume you have automatic HVAC system

Finally - Did you EVER have dealer do anything that might have required reprogramming the BCM or replacing it?

EDIT: Based on you having a GTP I think you will say that the relay is activating but will wait to hear what you have to say

[popsicle]

e2helper is back! :warped:

[jnak]

[GTPGuy82]

Ok I pulled the fuse, and this is what I saw:



That whole side was totally burned and melted. I'm no fuse expert, but I know when I fuse blows, the metal piece inside becomes unlinked, not the whole thing melts. I pulled the relay out too for the heck of it, it looked all right, with the exception of some small burn-type marks on one of the prongs.

Anyway, I replaced this fuse with another one, drove around a bit with the defroster on, and checked it again. Same thing, but not as bad (yet). The plastic on that same side is bubbling up and starting to melt again. E2helper man, you have any ideas? The dealership has never touched the car since I bought it.

[jnak]

Wow, that actually looks pretty scary. Fuses aren't supposed to do that

[grfnkl]

that's not good!!

[ToniCipriani]

Would something happen to short circuit your defroster mesh or some other wiring along?

Only thing I can think of doing that is the same thing blowing a fuse: overcurrent. But in your case the current is large enough to generate much more heat and melt it.

[CARD_G6]

Ummm... yeah. I'm gonna say that that looks bad.

Like Toni said, it appears to be overcurrent. Bad overcurrent.

[ahuhn]

i would say theres a short somewhere that pretty bad if its melting the fuse
just a FYI question you didnt repalced the fuse with a Harbor Freight fuse did you? theres a bulletin talking about a recall on them

Concerns with Harbor Freight Tools "Storehouse" Branded Blade Type Fuses
General Motors has become aware of a fuse recall by Harbor Freight Tools/Storehouse for a variety of aftermarket fuses. In two cases, these fuses have not provided protection for the wiring system of the vehicles they were customer installed in. Upon testing the 15 amp version, it was found that the fuse still would not "open" when shorted directly across the battery terminals.

How to Identify These Fuses




Packed in a 120 piece set, the fuse has a translucent, hard plastic, blue body with the amperage stamped into the top. There are no white painted numbers on the fuse to indicate amperage. There are no identifying marks on the fuse to tell who is making it. The fuses are known to be distributed by Harbor Freight Tools but there may be other marketers, and packaging of this style of fuse. It would be prudent to replace these fuses if found in a customers vehicle. Likewise, if wiring overheating is found you should check the fuse panel for the presence of this style of fuse.