Filament Inspection

Turn the ignition switch to the ON position.
Turn the rear window defroster switch on.
CAUTION:
- Directly touching the rear window defroster filament with the lead of the voltmeter will damage it. Wrap aluminum foil around the end of the lead and test the filament by touching it with the foil.
Connect the positive (+) lead of the voltmeter to the positive side of each filament and the negative (-) lead to ground.

Fig 1: Touching Rear Window Defroster Filament With Lead Of Voltmeter
Courtesy of MAZDA MOTORS CORP.

Gradually, slide the positive (+) lead from the positive side to the negative side and measure the voltage. Verify that the ohmmeter decreases accordingly.

If the voltage is not as specified or it changes rapidly, the filament is faulty. Repair the filament.

MEASUREMENT POINT

Measurement point	Voltage (Reference value)
(1) --> (2)	Approx. 12 V --> Approx. 0 V

Fig 2: Connecting Positive Lead Of Voltmeter To Positive Side Of Filament And Negative Lead To Ground

Courtesy of MAZDA MOTORS CORP.