Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2021 Mazda 3 BaseFACTORY OEM SERVICE PROCEDURE
Rear Window Defogger Inspection
- Switch the ignition ON (engine off).
- Turn the rear window defogger switch on.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.
- 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. 12 V to 0 V
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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