Section 32 (Defogger - Rear Window System): Operation
WARNING: This page is about a different car, the 1997 Mercury Sable and 1997 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.
The rear window defogger operates when ignition switch is in ON or ACC position. When rear defogger switch is pressed, a momentary ground signal is sent to GEM, which in turn grounds defogger relay. When defogger relay is activated, power from 40-amp maxi-fuse in power distribution box is supplied to rear defogger grid. GEM turns the system on for 10 minutes, then automatically turns power to rear window off.