Curiously, I've not yet found anything in the Haynes manual about troubleshooting a nonworking rear defroster. The fuses are all good, and the connections at the rear window seem okay, but that's as far as I've gotten so far. Any suggestions on what component of this system typically goes wrong?


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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

When mine quit on me it was the connector for the harness that is near the BCM. If you follow the harness from the rear of the car it will come to a connector and one of the pins burned out.

Sparkey05 wrote:When mine quit on me it was the connector for the harness that is near the BCM. If you follow the harness from the rear of the car it will come to a connector and one of the pins burned out.

Whats "BCM"? Do you have a picture of it? My rear Defroster isnt working either and I'm curious to fix mine also. Thanks.

-Infamous Ob

The computer in the driver side foot well. Just follow the wire from the back of the car and you'll see the connector. It's also pretty obvious when you get there if that is the problem

The connector is green if you need to know. 6 pin connector, same one that has the power windows attached to it. It has a bigger gauge wire which is the 30 amp rear defroster. The thing is always cooked and you can tell immediately

I assume this is accessed by removing the kick panel and the plastic door-sill trim?


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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

It's been a while but I do believe the sill plate had to be removed so you could pull the carpet back to get to it.

Under the carpet like an old Honda ECM, huh? Cool, I'll have a look for it when I get the time. Thanks for the info so far!


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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

I ran an add a fuse inline for the burnt out wire on mine, just bypassed the plug for that one wire. worked just fine after that. and yes all you have to do pull up the door sill/ kick panel then lift the carpet to get to it. should be a little left of where a clutch pedal would be.

Cinny wrote:I ran an add a fuse inline for the burnt out wire on mine, just bypassed the plug for that one wire. worked just fine after that. and yes all you have to do pull up the door sill/ kick panel then lift the carpet to get to it. should be a little left of where a clutch pedal would be.

It's located up under the Driver's side carpet?

Would you have a clutch pedal on the passenger side?

The sill plate was surprisingly easy to get out! Unfortunately(?), the green six-pin connector looked just fine. My DMM has been missing for a while, so when it turns up I'll have to go probing about for continuity. Though, maybe my cheap light-bulb power checker could work too ....

Where is the actual relay located that is actuated when you push the defrost button? Or does it send current through the button itself?


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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

*bump*

So ... no one knows whether the defrost current goes through the button in the dash or through a relay?


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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

I'm pretty sure the button is the relay. the defroster uses high current. Did you take the connector apart and inspect it, mine wasn't obvious until I did.

there is a thread about this. forgive my lack of memory but i though it was a purple fusible link wire. either way that wire is 98% of the issues. I had to fix it on my 00. you could always check for power at the grid to eliminate the window as unlikely as that would be

Connector is toasted on the inside - thanks a lot for the correction!

Now to see if I have a spare inline fuse holder and guess what rating fuse to use ... seems smarter to do that than to just splice in a bit of wire. If nothing else, I'm sure I can steal the fuse holder I used to power the HEI on my '81 LTD that's been sitting trannyless for over two years.


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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Well, that was easy. Turned out I'd installed that inline holder in the LTD with spade connectors at each end, and I even had spare spade connectors to make it completely disconnectable in its new home. The holder had a 20A mini fuse in it, so I switched it with the factory 30A fuse and plan to pick up probably a 25A for the factory panel next time I'm able.

Thanks again for the input!!


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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)