When you turn the ignition switch to the RUN position, voltage is supplied through fuse 10A to the rear defogger relay. When you press the rear defogger button, the Instrument Cluster (IPC) sends a class 2 message to the Body Control Module (PZM) to enable the rear defogger relay. The rear compartment fuse block then energizes the rear defogger relay, allowing voltage to the rear defogger.

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 on the IPC, when you press the rear defogger button.