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Rear Defroster not working

Tiny
FLEETMECH
  • MEMBER
  • 2007 CHEVROLET MONTE CARLO
I have a 2007 Monte Carlo. The rear defroster doesn't work. The light on the switch works, it has power to the grid, continuity through the grid, however it doesn't clear the window.
Thursday, November 18th, 2010 AT 6:53 PM

21 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Hello,

There is a relay that control the rear window defogger or there's an open wire within the grid on the window. Here is the wiring diagrams for the system so you can see how it works and the relay location along with a guide to test the relay to confirm the issue.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Check out the diagrams (Below). Please let us know what you find.
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Thursday, November 18th, 2010 AT 6:55 PM
Tiny
ANGIE92
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Thanks for this post I had a relay not working so I got a new one for $34.00 all fixed! I love this site.
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Saturday, January 19th, 2019 AT 4:40 PM
Tiny
TDUKE777
  • MEMBER
  • 2 POSTS
  • 2002 CHEVROLET MONTE CARLO
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 100,529 MILES
Why doesn't my rear defogger work in my 2002 monte carlo? I already changed the relay but that didn't help.
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Saturday, January 19th, 2019 AT 4:40 PM (Merged)
Tiny
SERVICE WRITER
  • MECHANIC
  • 9,123 POSTS
Did you check the fuse?
Did you check for power back to the defogger?
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Saturday, January 19th, 2019 AT 4:40 PM (Merged)
Tiny
TDUKE777
  • MEMBER
  • 2 POSTS
I didn't find a fuse for it just the relay and breaker. There is no power to the rear defogger. I tested it with a test light.
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Saturday, January 19th, 2019 AT 4:40 PM (Merged)
Tiny
SERVICE WRITER
  • MECHANIC
  • 9,123 POSTS
Check this 60 Amp fuse:


https://www.2carpros.com/forum/automotive_pictures/30961_x1_1.jpg



https://www.2carpros.com/forum/automotive_pictures/30961_z2_1.jpg

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Saturday, January 19th, 2019 AT 4:40 PM (Merged)
Tiny
DLSWEGER
  • MEMBER
  • 3 POSTS
  • 2005 CHEVROLET MONTE CARLO
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 71,000 MILES
The rear defroster stoped working. I have power coming out of the circuit when I push the defrost button. The window grid ohm's out ok. I have power on feed wire to the grid when it is unhooked from the window, but when I hook it up the power goes to 0 volts. Not sure what to check next.
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Chances are the switch is bad and can no longer handle the load from the grid. Check output power at the switch to see if it drops when you turn it on with the grid is plugged in. If it does, replace the switch.

Let me know what you find.

Joe
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
DLSWEGER
  • MEMBER
  • 3 POSTS
The switch lookes fine. I have 14 volts coming out of the circuir breaker, but at the grid 11.5 volts. Also when I plug into the gird and loose power I noticed when I unplug it the voltage goes from 1 volt and slowley climbes back up to 11.5, is there anything between the circuit breaker and the grid? Seemes like there may be a broken wire only maybe a coupple of strands holding on. Don
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
THere isn't anything between the two. It does sound like a broken wire, but the voltage wouldn't rebuild. How did you check the switch? I went through a similar problem on a dodge that ended up being the switch. It showed normal voltage until a load was on it. At that point, it couldn't handle the draw and output voltage would drop.
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
DLSWEGER
  • MEMBER
  • 3 POSTS
The power does not go through the switch. It is only control power to work the relay. I think the wire from the circuit breaker is bad some where. Going to ohm the wire from the breaker to the window connector to day. This should tell me if the wire is any good.
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
EYOUNGSR
  • MEMBER
  • 1 POST
  • 2003 CHEVROLET MONTE CARLO
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 113,000 MILES
Was wondering on why my rear window defrost all of a sudden, just stopped working. The light comes on that is on the dash, but the rear window never clears up. Is it possibly a fuse or the strips on the window?
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
RENAUDTN
  • MECHANIC
  • 636 POSTS
If none of the grids work, check fuse first, then relay (should hear it clicking when you push on the button), then check each tab on the two vertical bars (one on each side of your rear window).
Good luck
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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That is a good idea. There could be a break in the wire.

As far as the relay / switch, I understand what you are saying, but power still goes through the switch. It's just a thought.
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
FO TOG
  • MEMBER
  • 1 POST
I am having the same problem with a 03 Monte. I haven't pulled the switch out to check it yet, but when I do it seems like a simple jumper wire will tell if it's the switch that is the culprit. I will keep you posted.

I have always thought that the purpose of the switch was to provide a small load to the relay, so the relay was handling the bulk of the load.
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
GROUCHO47
  • MEMBER
  • 1 POST
  • 2004 CHEVROLET MONTE CARLO
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 33,000 MILES
I took the rear defog relay module out of fuse box on passenger side dash. I would like to know if there is a specific way it plugs back in. It COULD go in two different ways. There is a "corner cut off" on the module, should that be on the top left or bottom right when plugging back in? Ididn't want to plug it in and maybe screw EVERYTHING up Thanx--Jim
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
JDL
  • MECHANIC
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Welcome to the site. Use a testlite on relay socket, how many hot terminals, everything turned off. If only one is hot, that should be L3. There may be a wiring diagram on top of relay, look for the prong that matches up with L3.
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Saturday, January 19th, 2019 AT 4:41 PM (Merged)
Tiny
DEXTREME2
  • MEMBER
  • 1 POST
  • 2004 CHEVROLET MONTE CARLO
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 110,000 MILES
No rear window defrosters

currnetly my rear window defrosters are not working. I checked and all my fuses are good and I have a position terminal connection at my rear window defrosters. Is this an internal problem inside my cllimate control center or is there something that I've missed.

If my climate control center went bad. Can I replace my analoge display with a digital display.
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Saturday, January 19th, 2019 AT 4:42 PM (Merged)
Tiny
RHALL77
  • MECHANIC
  • 3,361 POSTS
Do you have voltage at the terminal at the rear window
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Saturday, January 19th, 2019 AT 4:42 PM (Merged)
Tiny
JAKESPEED63
  • MEMBER
  • 1 POST
This is the problem!
Burnt connection inside passenger side fuse box connector
Easiest repair, is to solder in a new wire from harness on backside of fuse box
Generally referred to as an “overlay “
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Sunday, July 14th, 2019 AT 8:12 AM

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