Filament Inspection

WARNING: This page is about a different car, the 2004 Mazda RX-8. However, it is still accessible from the selected car via links, so may be relevant.

Turn the ignition switch to the ON position.
Turn the rear window defroster switch on.

Fig 1: Inspecting Filament
Courtesy of MAZDA MOTORS CORP.
CAUTION:
- Directly touching the rear window defroster filament with the lead of the voltmeter could 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 tester to the positive side of each filament 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: Voltage Specification
Courtesy of MAZDA MOTORS CORP.

If the voltage changes rapidly, the filament has a malfunction. Repair the filament.

Fig 3: Measuring Voltage
Courtesy of MAZDA MOTORS CORP.