B+ is supplied to terminal 2 of the heated outside rear view mirror and rear window defogger relay K35 at all times. B+ is supplied to terminal 1 of the heated outside rear view mirror and rear window defogger relay K35 when the ignition switch is in the ON position. Ground is supplied to the heated outside rear view mirror and rear window defogger relay K35 at all times through G103.

When the rear window defogger switch is pressed, B+ is input into terminal 4 of the heated outside rear view mirror and rear window defogger relay K35. This energizes the relay and B+ is supplied to the radio antenna amplifier. B+ then travels from the radio antenna amplifier to the rear window defogger grid. Ground for the rear window defogger grid is permanently supplied by the radio antenna amplifier. The rear window defogger grid warms and defrosts the rear window.