TL* THE CONTACT OWNS A 2005 CHEVROLET SILVERADO 1500. WHILE DRIVING APPROXIMATELY 45 MPH WITH THE HEATER ACTIVATED, THE CONTACT NOTICED THAT SMOKE EMITTED FROM THE AIR VENTS. THE VEHICLE WAS MANEUVERED TO THE SIDE OF THE ROAD WHERE THE ENGINE WAS TURNED OFF. THE CONTACT INSPECTED UNDER THE DASHBOARD AND OBSERVED THAT THE WIRING HARNESS WAS MELTED. THERE WERE NO FLAMES VISIBLE. THE MANUFACTURER WAS NOT NOTIFIED OF THE PROBLEM. THE APPROXIMATE FAILURE MILEAGE WAS 60,000.