Heated Glass Element: Description and Operation

How the Circuit Works

The rear window defogger heats the rear window to remove condensation and restore visibility.

Voltage is applied at all times through fuse 11 to the rear window defogger relay. With the ignition switch in ON (II), voltage is also applied through fuse 4 to the rear window defogger relay coil and the defogger ON indicator.

When you press the rear window defogger switch once, the defogger timer circuit in the integrated control unit grounds the rear window defogger relay coil and the defogger ON indicator. The switch is a momentary switch and will return to the out position when released. The defogger ON indicator light then comes on, and the rear window defogger relay contacts close, applying voltage to the defogger grid on the surface of the rear window. The grid heats the rear window to remove any condensation from the glass.

You can turn off the window defogger by pressing the switch a second time, or by cycling the ignition switch to LOCK (0). A timer in the integrated control unit will automatically turn the defogger off after 20 to 30 minutes (USA) or 40 minutes (Canada) of continuous operation.