Rear Defogger Not Working Chev Cavalier 2003

My Rear Window Defogger Doesnt Work Anymore,the Switch Indicator Light Doesnt Come On.ive Checked The Fuses And They Are Fine,does Anyone Know What The Problem May Be?

Finally i got the problem corrected,i took it to the shop,it was the actual switch that was gone.Since it is all one unit,switch,heater,air conditioner,its expensive,a new unit is $375,after shopping around i found a used one for $125,with labour of two hours my total cam to $265.Last time i will ever buy north american junk again,im going foreign for sure.

Hello... check the small connectors on rear window to see if they are on tight... move them around a bit.. or try disconnecting them and reconnecting them to see if thats the problem.. If not then could be the switch itself.

Good luck

Hello... check the small connectors on rear window to see if they are on tight... move them around a bit.. or try disconnecting them and reconnecting them to see if thats the problem.. If not then could be the switch itself.

Good luckThanks for the tip,i will definitely try that.

If you switch the rear defrost on you can check the wires connected to the window with a 12v test light - one of them should be powered. If you get it working, later you can even check the small lines on the window with a test light to figure out which ones work and which don't because it's impossible to tell if it isn't cold enough out.

If you switch the rear defrost on you can check the wires connected to the window with a 12v test light - one of them should be powered. If you get it working, later you can even check the small lines on the window with a test light to figure out which ones work and which don't because it's impossible to tell if it isn't cold enough out.


Thanks for the advice,i will definitely try that.

Check behind the driver's side kick panel. There's an electrical connection there for the rear window defrost that will often get corroded.

Check behind the driver's side kick panel. There's an electrical connection there for the rear window defrost that will often get corroded.

I wanted to thank StevePT for his post. I had a rear defogger on a '02 Cavalier that was not working. After picking up a Haynes manual and reading up on forums, etc to better understand what I was dealing with, I began troubleshooting. There was no voltage at the rear defogger and a probe test confirmed there was no power there. The bulb illuminator above the switch would come on when I pressed it, and I could here it 'click' when I pressed it. The timer circuit also functioned by shutting off after 10-15 minutes. Nevertheless, I could not say for certain whether it was still allowing power to pass or not without testing further. The fuse was OK and there was power there, so I decided to move on. I also checked the defogger element itself by applying power direct from the battery by running two leads from the power and ground battery terminals to the contact terminals on the element. It was OK (and should have been since I was not getting power there anyway - but at least I knew it was OK). I then gathered information about the wiring and switch. It seemed that the orange wire going into the defogger switch harness was power from the battery (through the fuse). It was 'hot'. When the switch was pressed/activated, the purple wire out of the harness would then (theoretically if all was well) supply power to the positive terminal lead on the defogger element. I decided to jump these two leads and see if I was getting power at the defogger element terminal. I was not. But the orange (and now purple too) were hot and so I knew I had a break in the wire between the harness at the switch and the defogger element terminal. The other odd thing was that the wire was purple out of the switch harness but black at the defogger element, and I could not see how the same wire changed color - but I soon realized how. I was not too eager to trace a wire all the way back. I had also done a continuity test between the purple wire from the switch harness and the black degogger terminal wire (different color but supposedly the same wire) - I got 'some' resistance, which I thought was very peculiar... By this time, I was not sure what else to do. I decided to stick my head down under the steering wheel and was looking around at the wiring. I had recalled StevePT's post about something to do with the driver side kick panel, so I thought for a lark I would look around there. I peeled back a bit of carpet and noticed a dual harness (basically a big quick-disconnect). Oddly enough there was a big thick purple wire there, so I decided to test it for power -there was. On the other side was a big black (!) wire coming out. I tested for power - there was not! I cracked apart the harness and there terminal was corroded and slightly blackened (explaining my partial resistance and why there was not power getting through) - this was the problem. After cleaning up and reconnecting, I now have a defogger element that heats up again. Thanks to all, especially StevePT for his posting.

Hey thanks steve, your post saved me some cash and alot of troubleshooting. That was the exact fix for the defogger.
Thanks again

This thread contains good advice. I used this information to fix a '95 Cav last night. The connector was so fried that that plastic from the connector had melted into the carpet. After pulling the connector from the carpet, and disconnecting the connector, the purple wire had burned itself off of the metal tab in the connector. makes you wonder what someone was thinking (or if they were)....30 AMP fuse, big purple wire, big black wire, fed thu a small piece of metal in a connector......heat?

Thank you very much to the posters, especially Steve for taking the time to find out the problem. My 2001 Cavalier had same problem with rear defogger and it was caused by a corroded connector (the Purple wire problem).

One thing that I can add - there was no voltage at the rear defogger BUT when I disconnected either positive or ground lead, I could read 12.5V (no load) at the wires going to defogger, but with both connectors on terminals, there was 0V. (Seemed that the voltage was getting "dropped" some where else, high resistance and not enough current to blow the fuse - I had no wiring diagram and did not know where to begin tracing the wires from fuse panel back to defogger for high resistance connectors - This post told me where to look.)

I found the connector on driver side (right beside the hood release, under carpet). Disconnected by pressing tab in middle of connector and found the corroded terminal on Purple wire. Cleaned this contact and checked voltage at defogger - 12.5V was there and window started to get warm. Thanks again for the advice.

Mechanics advice went from replacing the whole rear window! to replacing the switch, etc. Minimum cost would be over $350. Wow, what a savings. Hope everyone who owns a Cavalier and has rear defog problem finds this thread.

Thanks again Steve and all others who helped.

Hey guys, all this info was incredible.. I had the same issue with my 2005 Cavalier, did everything, hopped on here, found the info steve posted, and bam! The black wire opposite the purple, melted the whole harness together! I went to Auto zone (retail parts in new england), they couldnt get me a new harness, went to the dealer, they couldnt find it in the system, but opted to work on it and clean it up, yada yada.. I told them no, i wanted the harness replaced.( melted, cracked, through the other end).. wasn't happening.. Now where the 2005 are a newer model, they have no books, no parts records, only because they are discontinued. ( GREAT!).. So figured even a trip to a junkyard might not help cause of the year being so different and the chance to find an 05 junked wasn't lookin good.... Nope, found quite a few Cavs there(01,03?) pulled down the carpet, IDENTICAL! So I grabbed 2 of the harnesses, just in case it happens again down the line, brought em up to the owner, told him what they were for and..................... 2 dollars for both of em!!!! Yea, no joke! I was pumped.. Went home, pulled all the fittings from the old harness, (you need the tiny black eyeglass screwdrivers to stick in there, cuz they'll rip right out of the adapter, (yup, i did it to one) there's little fins inside holding them in the harness, (for people like me who wouldnt know that)cut the 2 that were melted, refit them with the 2 from one of the sets, put the blue and gray clips back in, HALAYLUYA!!!! Freeking awesome!!! So it costed me roughly 4 bucks to fix it, an hour to jot down the layout, pullem out, remember how they went back in. You will need those round double end connecters (i have no idea what you call em) Red for the small ones? blue for the purple and black.. The 05's have 5 wires on each end... The black and purple go togther, and the rest just but in to them selves.. no idea what they go to.. but the defogger, (rear defrost) works so im really not gonna look into it any harder.. LOL. So if anyone needs to know what to get, or a picture to see exactly what it looks like, give me an email, and i'll shoot one over.. AGAIN THANKS TO EVERYONE ON THE PAGE. EVERYONE'S HELP WAS INCREDIBLE!!!!!!!!!! SAVED ME A FORTUNE!!!!

99 Cavalier 2 door 2.2: Same problem, same solution! Thanks to StevePT, I knew what to look for, and thanks to StevePT and RadarS, I knew exactly where to look for it! Purple wire tested "hot", black did not. Slight melting of the connector, only where the purple wire is soldered to it's connector prong. All other connections fine and functioning. Prong for the purple wire stuck to the melted and resolidified plastic around it. Ended up breaking it. So cut off the black and purple wires out of the connecter and reinstalled the connector for the other four circuits on it. Used a house electrical (110V) connector (The kind used to connect house light fixtures to their circuits) to connect the purple and and black wires. Turned the defogger on and (to the sound of angels singing!) the defogger terminals tested "hot"! :icesangel The glass started to get warm! Can't wait to fog up the windows to prove that the defogger works!

Result: Defogger works and praises of Automotive Forums and its users and posters will be forever sung!:bananasmi

Hi,
First of all, I want to thank everybody for all their helpful advice on this thread! I am working on a 2003 cavalier and trying to troubleshoot the rear defogger. I am using a multimeter to test voltage and when connected directly to the two wires disconnected from the rear window I read 14.5 V. With the passenger side wire (presumably ground) disconnected I can test all the wires running across the rear window and read 14.5 on all the wires all the way across. However, when I connect the passenger wire all voltage readings go to zero. I tried with a test light as well, and could not get the test light to show anything no matter what I did.

So to sum up my situation:
I have power at the driver side wire connecting the the window
I have continuity between the passenger wire and a body panel for ground
I have voltage across all wires all the way across the rear window as long as the passenger wire is disconnected
I have nothing when I hook up the ground wire

Thanks again for all the help with this issue thus far. I am just rather perplexed right now as to why this is not working. All the ingredients seem to be there, why won't it work?

If you show no voltage at the power side with the ground connected it means there's a point of very high resistance somewhere before the connector. With the ground disconnected there's infinite resistance so you'll have voltage. With it connected, if the resistance in the wire is enough, the resistance there acts as the load and the grid is just like a wire.

Thanks for the response. I did check resistance across the window and got 8 ohms, so that seems alright to me. Should I check something else?

Good call StevePT fooled with my rear defroster for hours and finally googled problem got to this web page and with your advice problem found and fix within 15 min. wire conector burned in the purple wire slot. So thanks for the info. from Kentucky.

I'm having the same issue with my rear defogger....seems to be notorious with cav's and GM's crappy designs. I'm going to be investigating soon and I think this forum and my Haynes manual will be a big help, but I have a feeling it's that wire that runs under the drivers side carpet. Just another example of why I stated doing my own car repairs and maintenance - told a mechanic about the problem and he immediately told me I would have to replace the entire rear window!! Too lazy to troubleshoot it and just see's $$$.

Created an account to thank StevePT for the fix and Bryan101010 for the additional detail about wire colours. I was dreading having to pull all the wiring to search for a break, and was relieved to discover this crappy connector problem. Probably something that should have led to a recall notice, given the number of people who seem to be affected and the fact that a melted connector means the possibility of fire. But oh well. I'm just glad to be able to see out my rear window again. Thanks!

This really was a helpful post. Had to create an account because of this one. I never would have found this problem if not for this thread. Only the difference is mine is not corroded at all... it seems to have melted inside the plug where the purple wire meets the black wire. the rest of the wiring running through it seems fine. can i simply replace the connector? how can i go about fixing this? any advice is really appreciated!

nevermind i just read RSMAINTENANCE04 (http://www.automotiveforums.com/vbulletin/member.php?u=595632)'s post that helped me alot.. awesome thread this one must have saved us all alot of money. :)

I had the same symptom on a cavalier vlx 2001. Thank you StevePT, and bryan101010. The famous green connector with contacts burned. ( see picture )