Rear window defroster problems

[PCRed]

Hi everyone, I searched the forums for a similar topic but nothing came up so hopefully someone can help me. Anyway, I've got a 93 Prelude and the other day my rear window defroster stopped working. A few weeks ago when I used it it turned on but wouldn't shut off again for 20 minutes or so or whenever the ignition was turned off but at least it turned on. Now nothing happens, no light comes on and no defrosting whatsoever... I had my mechanic look at it and he said its most likely a wiring problem and they don't mess with wiring stuff that much so it would be best to take it to a place that knows more about it. So does anyone by any chance have some suggestions on a simple fix before I spend more money trying to fix it?

Thanks a lot for the help!