924Board.org

Osiris · Joined: 01 May 2003 Posts: 91 Location: Muncie, IN

I have this problem, when I bought my car the rear defrost did not work. I have tried to diagnose the problem and have had no luck. My heated mirrors work, they're on the same relay right? I have replaced the fuse, no luck. I have an voltmeter so I can try that, where is the proper place to check for voltage, and what should it read on either side? I pretty sure there are no breaks in the defroster lines. This is starting to bother me.
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Keep a Chevy motor in a Chevy
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'87 924S 50K miles black/black

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

What I would do is start with a continuity at the connectors on the glass (need to make sure that you can get a complete circuit if voltage is reaching the glass).

Then you want to check for continuity ON the wiring connectors that connect to the glass.

If that does not isolate/identify the problem, turn the defroster on (with the key on of course), and check for voltage back on the connectors on the glass.

Somewhere, something is not connected, by following these instructions you can eliminate the glass and the wiring as the problem.

Sleykin · Posted: Sat Jun 05, 2004 4:39 am Post subject:

Interesting ... mine is doing the same thing. I have no power to the rear connectors. Driver's side should be hot when switched on and pass side should be ground. My heated mirrors work fine ... looks like I have a wiring problem but I have not started tracing it out.
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Glenn Neff
Medford, OR
87' 924S

Paul · Posted: Mon Jun 07, 2004 9:43 am Post subject:

Have you replaced your hatch struts recently?

Sleykin · Posted: Mon Jun 07, 2004 11:21 am Post subject:

Yes. The new struts came as two right side so I changed the wiring so I had the ground for the pass side and ran power around the shock on the left. It didn't work before I changed the shocks though. Just haven't gotten around to messing with it. Seems to me somebody said there were two fuses for the circuit. One lights the switch and heats the mirrors and the other runs the rear defrost so it may be as simple as diving under the dash and changing a fuse. I need to dig out the schematics and look again. Being summer and more concerned with having fun driving it has made me a bit negligent in the minor tweeks needed. Somehow it just gets tough to think about defrosters when it is 90* outside

We made a 250 mile run with the local PCA this weekend and it just ran so sweet I hate to touch anything:) Only problem I had was the ocassional screech from the right seat <LOL>
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Glenn Neff
Medford, OR
87' 924S

mjh937 · Joined: 26 Aug 2004 Posts: 2

I have the same problem with my 924S. I noticed that there was corrosion on the fuse and fuse holder. I sanded both off and it worked fine for a while until it corroded agaon. I have not bothered sanding it recently. I have not figured out how the mirror heat always works.

Hope this helps. If you have any idea how to stop the corrosion let me know. None of the other fuses have this problem.

Martyn.

Paul · Posted: Fri Aug 27, 2004 8:14 am Post subject:

The mirrors and the rear window are on different fuses in all 924s.

The Fife · Joined: 17 Mar 2004 Posts: 241 Location: San Antonio, Texas

Paul · Posted: Fri Aug 27, 2004 12:13 pm Post subject:

Wisconsin has had frost warnings already....I don't think we've hit 90 degrees yet this summer.

The Fife · Joined: 17 Mar 2004 Posts: 241 Location: San Antonio, Texas

Frost... it might get below freezing in 2 months but probably more. It doesn't snow much here, but it can really ice up sometimes!