Underhood Lamp: Description and Operation

CIRCUIT OPERATION
Circuit M1 from the Ignition Off Draw (IOD) fuse in cavity 16 of the Power Distribution Center (PDC) supplies battery voltage for the underhood lamp. A mercury switch, in series after the lamp, connects the lamp to ground on circuit Z1. When the hood is raised, mercury inside the switch moves to a position where it connects circuit M1 to ground circuit Z1, illuminating the lamp.