HELP !!WHAT IS THIS BOX??CAUGHT FIRE!!

I HAVE A 1992 EX-CAB 4X4 NISSAN HARDBODY.IT HAS BEEN SITTING FOR A YEAR. JUST NOW GETTING IT ON THE ROAD.DROVE IT A COUPLE OF TIMES AND WHILE IDLING IT STARTED SMOKING UNDER HOOD.OPENED IT AND THERE WAS A SMALL FLAME COMING FROM A SMALL 1"X1" LITTLE BOX ON PASSENGER SIDE OF INTAKE. I HAVE PICS OF IT. I DON'T KNOW WHAT IT IS. MAYBE ANIMALS CHEWED SOME WIRES OR SOMETHING,BUT,I WENT UNDER TRUCK AND LOOKED AROUND,BUT,FOUND NOTHING..WHEN I DROVE IT A COUPLE OF TIMES IT RAN GREAT,BUT,THEN THIS FIRE THING HAPPENED. IF THE PIC DOESN'T LOAD ,E-MAIL ME AND I WILL EMAIL YOU THE PICS. I TOOK. IT LOOKS TO HAVE A SMALL ORANGE/RED LITTLE LIGHT ON THE SIDE,BUT,I AM NOT SURE WHAT IT IS. ANY HELP WOULD BE GREATLY APPRECIATED.
TONY ([email protected])