Normal Operation
WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
Under normal operation, the heated backlight relay receives power from the central junction box through circuit 185 (BK). When the rear window defrost switch is depressed on the climate control assembly, a ground signal is sent to the instrument cluster module (ICM) through the circuit 688 (GY/LB). When the ICM receives ground through circuit 688 (GY/LB), the ICM grounds circuit 1009 (OG/YE) to activate the heated backlight relay. Power is then sent to the rear window defrost grid through circuit 186 (BN/LB) from the heated backlight relay. The rear window defrost grid is grounded to the chassis through circuit 1205 (BK).