Rear Window Defogger Circuit Description

When you turn the ignition switch to the RUN position, voltage is supplied through fuse 40A to the rear defogger relay. A solid state timer controls the battery voltage from fuse 40A through a relay. When you press the rear defogger switch, voltage is supplied through the class 2 data line from the instrument panel integration module through the rear integration module and out to the rear defogger relay. When you turn the ignition switch to RUN and press the rear defogger switch for the first time, the defog cycle lasts 10 minutes. Further operation results in 5 minute defog cycles. The defog cycle resets to 10 minutes when you turn the ignition switch to the OFF position and back to the RUN position.
The defogger ON indicator is an LED that illuminates when you turn the rear defogger ON.