Voltage is supplied to the rear defogger switch when the ignition switch is in RUN. When the rear defogger switch is ON, the contact closes. This provides voltage to the ON Indicator and the rear Defogger. The rear window becomes warm in order to remove fog from the surface of the window.

The contact in the rear defogger switch remains closed until the rear defogger switch is turned OFF or the Time Cycle is complete.

The timer also shuts OFF under the following conditions: