Up to VIN S5219999

With the ignition switch in ON or START, battery voltage is applied to both the coil and the contacts of the rear window defogger relay. When the rear window defogger switch is pressed, the electronic time and alarm control module senses ground on the WHT/RED wire through the rear window defogger switch. The electronic time and alarm control module will then ground the coil of the rear window defogger relay. The rear window defogger relay energizes and applies battery voltage to the rear window defogger and the rear window defogger indicator. A rear window defogger "ON" signal is also supplied to the engine control module (ECM). The ECM will then adjust idle speed to compensate for the extra electrical load.