Heated Glass Element Switch: Testing and Inspection

The rear window defogger switch has three functions: provide illumination for nighttime visibility, provide driver input for the rear window defogger relay and informs the driver of operation through an LED. The switch has two ground circuits, one for the illumination lamp and the other for a switch ground and LED ground.
1. Remove the defogger switch.

Rear Window Defogger Switch:

2. Using a jumper wire connect one end to a battery source, and the other to Pin 2 of the switch Connect a second jumper wire to negative source and the other end to Pin 3. The lamp should light, If not, replace switch. If OK, go to Step 3.
3. Using a voltmeter, test Cavity 2 for voltage. The voltage varies with panel intensity with the dimmer switch. If OK, go to Step 4. If not OK, test circuit back to the dimmer switch.
4. Using a jumper wire connect one end to a battery source, and the other to Pin 1 of the switch. Connect a second jumper wire to negative source and the other end to Pin 3. The LED should light, If not, replace defogger switch. If OK, go to Step 5.
5. Using a ohmmeter, connect the leads to Pin 4 and Pin 5. When the switch is at rest there should be no continuity, press and hold button, it should show continuity. If OK, test rear window defogger relay and circuit. If not OK, replace defogger switch.