System Testing
- Start engine. Turn rear defogger control switch on. Glass should feel warm after a few minutes. If glass is not warm, use a test light or voltmeter to check for battery voltage at grid feed wire. If battery voltage is present, perform GRID FILAMENT TEST .
- If battery voltage is not present, check fuse, wiring harness and control switch. If these components are okay, check rear defogger relay. Check time control unit.