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Filament Inspection

  1. Turn the ignition switch to ON position.
  2. Turn the rear window defroster switch on.
    CAUTION:
    • Directly touching the rear window defroster filament with the lead of the circuit tester will damage it. Wrap aluminum foil around the end of the lead and test the filament by touching it with the foil.
    Fig 1: Filament Inspection
    G01908064Courtesy of MAZDA MOTORS CORP.
  3. Connect the positive (+) lead of the voltmeter to the positive side of each filament and the negative (-) lead to ground.
    Fig 2: Voltage Specifications
    G01908065Courtesy of MAZDA MOTORS CORP.
    Fig 3: Moving Positive Lead of Voltmeter to Negative side of Filament
    G01908066Courtesy of MAZDA MOTORS CORP.
  4. Gradually, slide the positive (+) lead from the positive side to the negative side and measure the voltage. Verify that the voltage decrease accordingly.
    • If the voltage is not as specified or it changes rapidly, the filament is faulty. Repair the filament.