Heated Glass Element: Description and Operation

How the Circuit Works

Voltage is applied at all times through fuse 11 (in the under-hood fuse/relay box) to the rear window defogger relay contacts. With the ignition switch in ON (II), voltage is applied through fuse 14 (in the under-dash fuse/relay box) to the rear window defogger relay coil.

When you push the defogger switch (in the heater control panel) once, a path to ground is provided by the control panel to the rear window defogger relay. The defogger ON indicator light comes on, and the rear window defogger relay contacts close. Voltage is applied to the defogger grid on the inside surface of the rear window, and the grid heats the rear window to remove any fog from the glass.

You can turn the defogger off by pushing the defogger switch a second time or by turning the ignition switch to LOCK (0). A timer in the control panel will turn the defogger off automatically after it has been on continuously for about 20 minutes.