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Rear defroster

I have a 1988 924s and the rear defroster does not work. I have read Clarke's and every thing else on the internet and found no help. The struts are fairly new, the relay is new, the switch is new. I tested it per Clarke's. I have 12V on the left side and have 12V on the right side. Clarke's said it should be zero on the right side but doesn't tell how to fix it if it doesn't..

My struts are installed properly. The right strut is grounded properly. The wires are still soldered to the hatch. I unhooked the grid from the struts and the meter showed continuity but zero ohms. Is this normal? I would think the grid should have resistance causing the heat. If the grid is bad what can I do about it. I checked each grid wire and have continuity on each one.

Any ideas? Thanks.
Old 02-10-2019, 01:17 PM
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The right and the left strut should be different, you could have them interchanged or two of the same type.
Old 02-11-2019, 02:54 AM
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Quote:
Originally Posted by djnolan View Post
The right and the left strut should be different, you could have them interchanged or two of the same type.
I have had issue with mine and it was the struts - left and right are different, just don't put them 180 opposite.

It sounds like you went thru all of this. I'm at a loss.
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Old 02-11-2019, 04:38 AM
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The struts are the right ones in the right place. I checked that first thing.
Old 02-11-2019, 06:41 AM
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Ok think logically. When you operate the switch and get 12v on the left (supply) side, then your fuse, switch, relay and supply side wiring are all good. If you also get 12v on the right (ground) side then your defrost element is also good. The reason it’s no heating up is bacause you are missing a ground on the right side, without a ground the circuit is incomplete and the 12v will simply hang around on the right side strut.

Look at where the defrost element exits the glass and enters the right strut, it then runs down the right strut to a ground point on the chassis. It is that ground point where your problem likely lies, it’s not grounded for some reason and you need to inspect why.
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Old 02-11-2019, 08:57 AM
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The right strut should have a metal lower socket end to provide a ground path, the left side strut lower end is plastic.
Old 02-11-2019, 03:14 PM
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I unplugged the right strut. I hooked a ground wire from the grid to a good ground. Still nothing. If someone has a few minutes could they unhook the upper wires from their struts and run an ohm meter across their grid and see what the reading is. Thanks.
Old 02-12-2019, 08:58 AM
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bump
Old 02-16-2019, 02:54 AM
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Does your right strut have a wire going to the body? This wire connects to the strut plastic slider switch for the hatch light, and the wire is not the defroster ground. The defroster ground is through the metal strut knuckle to the body.

Can you take a picture of the struts with the hatch open to make sure it assembled correctly and they are the 2 correct struts?

Last edited by djnolan; 02-18-2019 at 12:27 PM..
Old 02-16-2019, 05:51 AM
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