Checking heater wires
1. Turn the ignition switch to the "ON" position.
2. Turn on the rear window defroster.
Caution: When measuring voltage, wrap the end of the voltmeter probe with aluminum foil and press the edge of the foil to the wire with your finger.
3. Connect the positive lead of the voltmeter to side (1) of the wire and connect the negative lead to ground.
4. Gradually move the probe from side (1) to side (2). Check that the voltage gradually decreases from 12 V to 0 V.
If there is no voltage or the voltage changes quickly, the wire is damaged. Repair the wire.
Wire repair
1. Clean the ends of the wire at the break point with solvent and stick protective tape on both ends of the wire.
2. Mix the repair compound thoroughly and apply a drop of the substance to the wire using a thin-ended brush.
Content based on information from (MazBook.ru)
Repair compound: DUPONT PASTE No.4817 or similar substance.
3. After a few minutes, remove the protective film and leave the composition to harden for 24 hours.
Removal and installation the rear window defroster switch
1. Disconnect the cable from the negative terminal of the battery.
2. Remove the center panel assembly.
3. Disconnect the connector from the rear window defroster switch.
4. Disconnect the connector from the hazard warning switch.
5. Turn down at the bottom.
6. Remove the rear window defroster switch.
7. Install in the reverse order of removal.