Rear Window Defogger - Printed Heater - Repair Procedures

Inspection

Wrap tin foil around the tip of the voltmeter probe to prevent damage to the heater line. Press the tin foil with your hand and move the tin foil along the grid line to check for an open circuit.

1. 1
   Turn on the heater switch and use a voltmeter to measure the voltage of each heater line in the center of the glass. If the voltmeter shows 6V for a conductive line, the rear window line is considered to be in good condition.

   

2. 2
   If the conductive line is broken in the area between the center and the (+) terminal, the voltmeter will show 12V.

   

3. 3
   If the conductive line is broken in the area between the center and the (-) terminal, the voltmeter will show 0V.

   

4. 4
   To check for an open circuit, slowly move the measuring probe along the section where an open circuit appears to exist. Try to find the point where the voltage becomes 0V. The point where the voltage changed is the open circuit point.

   

5. 5
   Use an ohmmeter to measure the resistance of each heater line between the terminal and the center of the grid line, and between the same terminal and the center of one adjacent heater line. The section with the broken heater line will have twice the resistance of other sections. In the affected section, move the test lead to the position where the resistance changes sharply.

   

6. 6
   Conductive paint.
7. 7
   Paint thinner.
8. 8
   Insulating tape.
9. 9
   Silicone remover.
10. 10
    Using a fine brush: Wipe the glass next to the broken heater line, clean it with a silicone remover, and attach masking tape as shown in the illustration. Shake the conductive paint container and apply three coats with a brush at approximately 15-minute intervals. Remove the tape and allow sufficient drying time before applying power. For a better finish, scrape off excess paint with a knife after the paint has completely dried. (Allow 24 hours.)