General Description

The rear defogger system consists of a rear defog switch (part of HVAC control head), rear defog relay, located in the Underhood Fuse Block (UHFB), Body Control Module (BCM) and rear defog grid in the rear window The coil side of rear defog relay is fed battery voltage from the 25 A DEFOG fuse in UHFB. Voltage flows through the coil, through circuit 193 to BCM where it is switched to ground when BCM receives the signal from rear defog switch.

When the BCM grounds the coil side of the relay, the relay is energized and current flows through the 25 A DEFOG fuse in the UHFB and through circuit 293 to the rear defog grid. The BCM will keep the rear defog relay energized for approximately 15 minutes the first time the switch is pressed, and for approximately 7 1/2 minutes if the rear defog switch is pressed again.