The contact own a 2017 Chevrolet Silverado. The contact noticed that the plastic piece from the rear defroster window was sparking and smoke was coming from rear window. In addition, the plastic was melting. The vehicle was taken to the dealer where it was diagnosed that the rear window defroster assembly needed to be replaced. The vehicle was not repaired, The manufacturer was notified of the failure, The approximate failure mileage was 68,000.