Rear Window Defroster Inspection

Switch the ignition ON (engine off).
Turn the rear window defroster switch on.

Fig 1: Pushing Rear Window Defroster Aluminum Foil
Courtesy of MAZDA MOTORS CORP.
CAUTION:
- Directly touching the rear window defroster with the lead of the tester could damage it. Wrap aluminum foil around the end of the lead and inspect the rear window defroster by touching it with the aluminum foil.
Connect the positive lead of the tester to the positive side of each rear window defroster and the negative lead to ground.

Gradually slide the positive lead from the positive side to the negative side and verify that the voltage decreases accordingly.

Fig 2: Measuring Rear Window Defroster Voltage

Courtesy of MAZDA MOTORS CORP.

If the voltage changes rapidly, the rear window defroster has a malfunction. Repair the rear window defroster. (Refer to REAR WINDOW DEFROSTER/GLASS ANTENNA REPAIR .)

Measured part	Voltage (Reference)
(1) to (2)	Approx. 11 V to 0 V