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From: jimv@apollo.uucp (James Vienneau)
Newsgroups: net.auto.tech
Subject: Re: '81 Malibu rear window defroster...
Message-ID: <2a44bdcc.46b9@apollo.uucp>
Date: Thu, 21-Nov-85 09:36:35 EST
Article-I.D.: apollo.2a44bdcc.46b9
Posted: Thu Nov 21 09:36:35 1985
Date-Received: Sat, 23-Nov-85 10:32:46 EST
References: <1703@uwmacc.UUCP>
Organization: Apollo Computer, Chelmsford, Mass.
Lines: 19

> The rear-window defroster in my '81 Malibu has stopped working.
> I checked all the fuses in the fuse box, and none appear to be
> defective (there was a mysterious large metal-enclosed one that
> defied visual inspection).  The dashboard indicator light still
> works when I activate the defroster.  The connections at the
> rear window appear to be intact.  Can anyone suggest further
> troubleshooting?  I'd sure appreciate it.

I had an 81 Malibu wagon with the same failure. That metal box is
a relay not a fuse. The defogger draws too much current to use an
ordinary switch, also the relay has a timer built in to attempt to 
keep the defogger from melting  itself. In mine the relay went bad
(~$30). Have you checked to see if power is getting to the defogger
with a voltmeter or light? If it's not, it would be my guess that it's
the relay. If it is, then I'd suspect the window grid itself is open. 

A WORD TO THE WISE: NEVER leave a GM defogger on any longer than
necessary. They have a really nasty habit of cooking themselves if
just turned on and left for the timer to shut them off.