Windshield Defogger Operation

C68 

When the HVAC control module receives a windshield defog request from the HVAC controls defogger switch, the HVAC control module sends a serial data message to the body control module. The body control module will then provide 12 V to the windshield defogger relay, the windshield defogger relay will be energized and will provide B+ voltage to the left and right windshield defogger relays which will also become energized and will provide B+ voltage to the left and right side of the windshield defogger grid

C41, C60 

The body control module monitors the voltage level on the windshield defogger signal circuit, when the windshield defogger switch is pressed, the voltage in the signal circuit is pulled low, the body control module will then provide 12 V to the windshield defogger indicator and to the windshield defogger relay. The windshield defogger relay will be energized and will provide B+ voltage to the left and right windshield defogger relays which will also become energized and will provide B+ voltage to the left side and right side of the windshield defogger grid