Rear Window Defogger Mystery Module

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?