2000 FORD EXPEDITION PARKED FOR MORE THAN 3 HOURS. NOTICED WHITE SMOKE COMING FROM UNDER HOOD. STRONG SMELL OF 'ELECTRICAL FIRE'. WE WERE ABLE TO SMOLDER BEFORE FLAMES IGNITED AND BEFORE FIRE DEPARTMENT ARRIVED. THE ORIGIN WAS, VERY OBVIOUSLY, THE SCDS. IT WAS MELTED AND SMOKING. *NM