Circuit/System Description

Battery positive voltage is supplied through a 30A fuse in the underhood fuse block, to the rear defogger relay switched input. When the rear window defogger switch is pressed, The HVAC control module commands the rear window defogger system by supplying voltage to the rear defogger relay coil. The rear defogger relay is energized and the defogger indicator is illuminated. With the relay energized, battery positive voltage is allowed from the relay switched input through the switch contacts and out the relay switched output to the rear window defogger grid.