Filament Inspection

WARNING: This page is about a different car, the 2005 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.
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.
Fig 1: Inspecting Filament
Courtesy of MAZDA MOTORS CORP.
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.
- If the voltage changes rapidly, the filament has a malfunction. Repair the filament.
Fig 2: Connecting Positive Lead Of Tester To Positive Side Of Each Filament And Negative Lead To Ground
Courtesy of MAZDA MOTORS CORP.