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Rear Window Defogger Mystery Module

3772 Views 7 Replies 6 Participants Last post by  KwadKen
The rear window defogger stopped working on my 2011 OB Premium w/winter package. It was repaired under warranty but the dealer tech found that the wiring for the rear defogger did not match the service manual diagrams - he found a vented plastic covered module where the correct colored wires entered and wires colored differently from the service manual diagram emerged to the rear window grid. The tech called Subaru to ask what this module might be (he could see what appeared to be a coil of heavier gage wire inside through the vent holes of the module). Subaru had no clue. My guess is that this is a ballast resistor for a circuit serving the rear window, the rear-view mirrors and the windshield wiper heat. Anyone have a clue?
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Possible remedy.
Locate the fuse for this component in the fuse box; see if it's OK; if not, replace the fuse with higher amps rating and see, it it works.
Then watch the car burn as the wires are asked to carry more current than they're rated for. The circuits are rated based on the wiring and the devices on the circuit, too much current on a wire is just asking for the insulation to melt and cause a short or fire.

The rear defroster should be powered through a relay, the "on" signal should command the relay to close and send power over bigger wires to the defroster grid.
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