Rear Window Defogger Operation

Battery positive voltage is supplied through the DEF fuse, in the IP fuse block, to the rear window defogger relay switch. With the ignition in the ON position, ignition voltage is supplied through the GAUGE fuse, in the IP fuse block, to the rear window defogger relay coil, and to the rear window defogger switch. When you depress the rear window defogger switch, the switch illuminates the rear window defogger indicator and grounds the control circuit of the rear window defogger relay. This energizes the rear window defogger relay and allows battery positive voltage from the relay switch feed circuit through the closed switch contacts and out the relay switched output to the rear window defogger grid. Ground for the rear window defogger grid is provided by G300.

The rear defogger switch incorporates an integral indicator lamp and an integral timing circuit. The indicator illuminates when the rear defogger switch is depressed. The defogger cycle lasts approximately 10-15 minutes and then shuts off automatically. Defogger operation may be cancelled before the cycle ends by depressing the defogger switch, or by turning the ignition switch to the OFF position.

The rear defogger switch may be depressed for additional cycles depending on the following conditions:

• Vehicle speed
• Outside window temperature
• Atmospheric pressure
• Number of passengers