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disconnect wire to rear defroster

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Old 12-06-2007, 08:53 AM
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97BlckCpe
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Default disconnect wire to rear defroster

How do you disconnect the wire from the rear defroster? I was told this may take care of this problem....
I have an ongoing problem with my rear defroster. When I turn it on there is an incredible screeching sound that comes out of the speakers.
The sound system was ripped apart in and out and its not that. I don’t know what to do because now there is a a static sound that comes through the speakers even with the sound system off.

I cant take it this noise in the car is driving me crazy! I have had the audio techs spend a lot a time costing a lot of $ in service fees .
In the summer I did crack the drivers side mirror and replaced it with a non heated mirror. This is the only thing that I can think of …
Old 12-06-2007, 09:14 AM
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87SAM
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Can't say how to disconnect but below is a service bulletin concerning your problem.

Document ID# 1583196
1997 Chevrolet/Geo Corvette


--------------------------------------------------------------------------------

Poor Radio Reception or Radio Static/Increased Interference with Rear Window Defogger On or Some Rear Window Defogger Grids may be Inoperative (Diagnose and Repair Rear Window Defogger Heating Grid) #03-08-44-005C - (Jan 19, 2005)
Poor Radio Reception or Radio Static/Increased Interference with Rear Window Defogger On or Some Rear Window Defogger Grids May Be Inoperative (Diagnose and Repair Rear Window Defogger Heating Grid)
1997-2005 Buick Century, LeSabre, Park Avenue, Regal

1997-2001 Cadillac Catera

1997-2002 Cadillac Eldorado

1997-2004 Cadillac Seville

1997-2005 Cadillac DeVille

2003-2005 Cadillac CTS

1997-2005 Chevrolet Corvette

2000-2005 Chevrolet Impala, Monte Carlo

2004-2005 Chevrolet Epica, Malibu

1997-2003 Oldsmobile Aurora

1998-2002 Oldsmobile Intrigue

1999-2004 Oldsmobile Alero

1997-2005 Pontiac Grand Am, Grand Prix

2004-2005 Pontiac GTO

This bulletin is being revised to add the 2005 model year and update the part number information for Permatex Quick Grid. Please discard Corporate Bulletin Number 03-08-44-005B (Section 08 -- Body and Accessories).

Condition
Some customers may comment that the radio has poor reception or radio static/increased interference when the rear window defogger is turned on. Also, some rear window defogger grids may be inoperative.

Cause
This condition may be due to microscopic cracks in the electrically heated grids of the rear window defogger. These cracks may cause electrical interference when the rear defogger is on and this could affect radio reception.

Background
The addition of vertical grid lines to the heated back window defogger circuits has made it difficult to detect broken defogger grid lines. In the past, it was a simple matter to use a voltmeter to check the continuity of each grid line in order to locate a non-functional line. New design back windows have two vertical grid lines that connect all of the horizontal grid lines together, thereby providing alternate routes for the electrical current to follow. This makes the old test method ineffective.

Materials Required
• Permatex Quick Grid, GM P/N 12346001, or equivalent

• A small ball of fine steel wool Type 00, or

• Optional -- A strip of liquid crystal heat sensitive paper, 51 mm x 305 mm (2 in x 12 in) or similar size (Contact Edmund Scientific at 800-728-6999 for part number CR30723-70 or go to www.scientificsonline.com), or

• Optional -- A portable infrared thermometer, GE-46819, available from Kent-Moore (1-800-345-2233), or equivalent.

Correction
There are three distinct zones across the back window that must be checked. They are:

• the driver's side outboard of the two vertical lines

• the passenger side outboard of the two vertical lines

• the central zone that falls between the two vertical lines

To detect a broken grid line in any of the above three zones and to isolate the exact location of the break, perform the following:

Caution:

• Approved safety glasses and gloves should be worn when performing this procedure to reduce the chance of personal injury.

• Cover the rear shelf area to prevent damage to the interior trim material.


Start the engine and turn on the back window defogger.
Important: The first place to check should be the driver side segment 2 to 3 lines up from the bottom about 380-385 mm (15-15.2 in) from the buss bar.


Take the ball of fine steel wool and twist one end to a point. Move the point slowly across each grid line. Be sure to start at the far side of the zone and move it to the opposite side of the zone. When you bridge the grid line break with the steel wool, you will see a small spark. Repeat the test over the same area to be sure you have accurately located the break. Mark the exact location of the grid line break. Repeat this portion of the test for each grid line. If you do not see a spark at any point, it is possible that there are two breaks in the same line and zone. Close visual inspection using a magnifying glass may be the only way to locate breaks in this case.
The following are provided as a alternative way to detect a non-functional grid line. If available, use in addition to the steel wool.
Method using liquid crystal heat sensitive paper.
Important: The first part of the test must be completed quickly before the entire surface of the back window becomes warm.


From outside the vehicle, place the heat sensitive paper (dull surface in contact with the glass) against the top driver side grid line. Start the engine and turn on the back window defogger. A distinct color change will take place at each conductive grid line. Repeat for the bottom grid lines until they have all been checked in the driver side zone.
Repeat the process for the passenger side and center area zones.
If no color change is noted for a grid line, place a crayon or china marker check mark beside it. Mark each grid line in the zone where it is non-conductive and therefore not heating up. More than one broken grid line may be found.
Method using a portable infrared thermometer.
Start the engine and turn on the rear back window defogger.
From inside the vehicle, start at the top driver side grid line and slowly run the portable infrared thermometer vertically down the rear window contacting each grid line. You should be able to see a district variation in temperature readings.
Mark each grid line in the zone where it is non-conductive and, therefore, not heating up. More than one broken grid line may be found.
Repeat the process for the passenger side and center area zones.
Use Permatex Quick Grid, GM P/N 12346001, or equivalent, to repair each broken grid line. Follow the manufacturer's instructions.
Wait 24 hours before turning the defogger on, or the repair can be fast cured using a heat gun, 260°C -- 371°C (500°F -- 700°F). Hold the heat gun within 25 - 51 mm (1- 2 in) from the repair point for 2 to 3 minutes.
Recheck the grid line with the heat sensitive paper or a portable infrared thermometer to ensure that the line is now functional and that the repair was successful.
Old 12-06-2007, 09:29 AM
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97BlckCpe
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87SAM: this is an incredible help and I will pass it along to an audio/electrician tech so he can go to work again to find out if this is the factor. But for now the easiest most finacially sound way to fix this noise would be to test out the wire, disconnect it and see if that is the problem. thanks again prinitn and heading over to him later to see if he can figure it out in his mind.
Now though back to my original question anyone know if the wire can be easily disconnected from the window.
Old 12-06-2007, 10:36 AM
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87SAM
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I don't see anything on how to remove, it may be soldered. Could try removing the fuse, although fuse 18 looks to be needed for other HVAC functions. There is mini relay 46 under the passenger side toe board.

Old 12-06-2007, 10:39 AM
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JMartin
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Should be a plastic type plug, plugged into the window behind the seat area
Old 12-06-2007, 10:41 AM
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97BlckCpe
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ok so another great suggeestion thanks... but if i were to remove the switch which one would you suggest and what other things would I be shutting down. Sorry to seem like such an idiot but the last name Blair and Electric in my family is like oil and water.
Old 12-06-2007, 10:47 AM
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97BlckCpe
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Originally Posted by JMartin
Should be a plastic type plug, plugged into the window behind the seat area
behind the pass. seat?
Old 12-06-2007, 12:19 PM
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97BlckCpe
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Originally Posted by JMartin
Should be a plastic type plug, plugged into the window behind the seat area
Pulling the plug on the rear defroster didnt work ...

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