Rear Window Defogger Inspection

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

Switch the ignition ON (engine off).
Turn the rear window defogger switch on.

Fig 1: Inspecting Rear Window Defogger
Courtesy of MAZDA MOTORS CORP.
CAUTION:
- Directly touching the rear window defogger with the lead of the tester could damage it. Wrap aluminum foil around the end of the lead and inspect the rear window defogger by touching it with the aluminum foil.
Connect the positive lead of the tester to the positive side of each rear window defogger 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: Inspecting Rear Window Defogger
Courtesy of MAZDA MOTORS CORP.
- If the voltage changes rapidly, the rear window defogger has a malfunction. Repair the rear window defogger. (See REAR WINDOW DEFOGGER/GLASS ANTENNA REPAIR .)

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