2. Elements with small breaks can be restored without removing the rear window.
Examination
3. Set the ignition switch and heater switch to the ON position.
4. Connect the positive electrode of the voltmeter to the positive terminal of the heating element, and the negative electrode to the terminal of the heater ground loop. If the device does not detect the presence of voltage generated by the battery, inspect the fuse, heating switch and related wiring. If voltage is present, but all or a section of the heating element does not operate, perform the following test.
5. When measuring voltage during the next two tests, wrap the negative electrode of the voltmeter with aluminum foil and take measurements by pressing the foil against the heating element with your finger (see illustration). Connect the negative electrode to the ground terminal of the heating element.
21.5. To measure the voltage in the rear window defroster sections, wrap aluminum foil around the negative electrode of the voltmeter and press the foil against the element with your fingers
6. Take voltage measurements by alternately connecting the foil-wrapped electrode to the center of each section of the element (see illustration). If the voltage is 5 - 6 V, this indicates that the section does not have a break. A zero voltage measurement indicates the presence of a break between the center of the section and the grounding terminal. A voltage of 10 - 12V indicates the presence of a broken section between the center and the ground loop. Examine each section of the heater.
21.6. When identifying a section of the heating element that has a break, measure the voltage by connecting a foil-wrapped electrode to the center of each section; if the voltage is 6V, this indicates that the element is in good condition
7. If no break is found in the element, connect the negative electrode of the voltmeter to the grounding point on the car body. If the ground loop does not have an open or short circuit, then the voltmeter readings should not change.
8. To determine the location of the heating element break, connect the negative electrode of a voltmeter to the ground terminal of the rear window defroster. Connect the positive electrode of the voltmeter, wrapped in foil, to the positive terminal of the heating element, then move the electrode along the element towards the negative terminal. The point at which the voltmeter reading deviates a few volts from zero is the breaking point of the heating element (see illustration).
21.8. To detect the location of a broken heating element, connect the negative electrode of a voltmeter to the ground terminal of the rear window defroster; connect the positive electrode of the voltmeter, wrapped in foil, to the positive terminal of the heating element and move the electrode along the element towards the negative terminal; the point at which the voltmeter readings deviate by several volts from the zero mark corresponds to a break in the heating element
Repair
9. Repair the rupture of the heating element using a special repair kit (for example, DuPont paste No. 4817 or similar product). The kit also includes a flexible electrically conductive epoxy resin.
10. Turn off the heater and wait for it to cool for a few minutes, then repair the break.
11. Sand the area adjacent to the tear, then degrease it with alcohol
12. Place two strips of adhesive tape on the glass to insulate the area of the heating element to be restored.
13. Prepare the restoration composition from the repair kit, following the accompanying instructions.
14. Apply the compound to the area to be restored between the strips of tape, overlapping the torn element by 20 mm on each side (see illustration).
21.14. Before restoring an element using a repair kit, cover the damaged area with tape, then apply a restorative compound
15. No earlier than a day later, remove the strips of adhesive flax and check the functionality of the restored element.