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Old 01-19-2010, 11:43 PM   #1
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Default Rear window defroster

I am having trouble with the rear window defrost, not working on my 96 bonneville.
I have replaced the relay under the passenger side hush panel, checked and cleaned the BUS hook-ups that are on the passenger and driver side, under the carpet. Both looked pretty good. metal strips inside of the bus hook-ups were clean. I took a emory cloth and just touched them up a little.
I unhooked the wires that hook to the glass on both sides and they both look and hook tightly.
Where do I go from here to look at next?????
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Old 01-20-2010, 12:07 AM   #2
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did you verify that the fuse isn't blown, and there'* correct voltage/triggers on the relay terminals?
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Old 01-20-2010, 02:31 PM   #3
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I checked the fuse, and bought a new relay. So I know that they are both good,
How do I check for the correct voltage/triggers on the relay terminals? Is this on the relay itself, or where it plugs into the panel?
Thanks.
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Old 01-20-2010, 02:57 PM   #4
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did you check to see if the voltage is getting to the glass; it could be the defrost grid got damaged causeing it not to work. one side should be voltage and the other side should be ground
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Old 01-25-2010, 11:51 PM   #5
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How do I check to see if I have voltage to one side, and ground to the other. Is it as simple as getting a good ground somewhere on the chassis, and then putting a test light on the grid. or do I need to get a ohm meter and do it that way?
Thanks
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Old 01-26-2010, 09:16 AM   #6
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Disconnect both wires from heater grid, attach your multi-meter and check for voltage. If no voltage shows, then disconnect one lead and ground it. If nothing, switch the leads and test ground again. I'm not sure which wire is positive.

If you get voltage when you connect only one wire and connect to chassis ground, then your defroster ground is bad somewhere.

If you do get voltage at both wires, then you may have a open in your heating grid somewhere. Let us know what you find out when you test the wires.
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Old 01-26-2010, 09:51 AM   #7
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Sorry about that, I just went out and verified. For some reason I was thinking of the rear glass on my blazer.

Your going to have to pull out both rear pillar plastic trim pieces to get to the wiring. You can still do the voltage test with them connected.
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