Headlight Switch problems of the 1999 Lincoln Navigator

The contact owns a 1999 Lincoln Navigator. When engaging the high beam switch for the headlights the lights will not activate. When the lights finally turn on they appear dull. The wiring for the headlights have melted. The vehicle was taken to the dealer and he was advised that depending on where the vehicle was manufactured they would assume responsibility. The failure mileage was 150,000.