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Rear Window Defroster Inspection

Switch the ignition ON (engine off).
Turn the rear window defroster switch on.
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 1: Touching Rear Window Defroster With Lead Of Tester

G09783917

Courtesy of MAZDA MOTORS CORP.

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

Fig 2: Measuring Voltage Rear Window Defroster
Courtesy of MAZDA MOTORS CORP.

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