Rear Defogger Switch: Testing and Inspection

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT AND ISOLATE THE BATTERY NEGATIVE GROUND. CABLE, THEN WAIT TWO MINUTES FOR THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE BEFORE PERFORMING FURTHER DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY OR DEATH.

NOTE: For circuit descriptions and diagrams, refer to Rear Window Defogger Wiring Diagrams.

1. Disconnect and isolate the negative battery cable. Remove the accessory switch bezel from the instrument panel and disconnect the wire harness connector from the defogger switch.
2. Check for continuity between the ground circuit cavity of the defogger switch wire harness connector and a good ground. There should be continuity. If OK, go to Step 3. If not OK, repair the open circuit as required.

Rear Window Defogger Switch Continuity:

3. Check for continuity between the ground circuit terminal and the rear window defogger switch sense circuit terminal on the back of the defogger switch housing. There should be momentary continuity as the defogger switch is pressed, and then no continuity. If OK, test the instrument cluster refer to testing . If not OK, replace the faulty rear window defogger switch.