Rear Defogger: Testing and Inspection
TESTING GRID LINESTo locate inoperative grid lines, turn ignition key to the On position and turn the rear window defogger switch to the On position. Attach the black lead of the multimeter (set to the 20 volt scale) to ground. Lightly touch the red lead of each grid line.
The multimeter should display battery voltage at the positive side of each grid line. The voltmeter should gradually display less voltage as the red lead of the multimeter is moved toward the ground side of the vehicle.
If the reading shows battery voltage as the red lead is moved across the grid lines and then makes a sudden jump down to zero volts (ground) that grid line has an open it it.
Items Required:
- GM or Saturn Rear Window Defogger Repair Kit PN/12345345 (or equivalent)
- Heat Gun - capable of 260 degrees C (500 degrees F)
REPAIR PROCEDURE
1. Disconnect battery feed rear window defogger system.
2. Inspect rear window defogger grid lines and mark grid line breaks on outside of glass with a grease pencil.
3. Clean grid line area to be repaired. Buff with steel wool and wipe clean using cloth dampened with alcohol. Buff and clean about 6 mm (1/4 in.) beyond each side of break in guide line.
IMPORTANT: Repair decal or tape must be used to control width of repair area. If decal is used, be sure the die-cut metering slot is the same width as the grid line.
4. Install grid line repair decal or two strips of tape positioned above and below repair area.
5. At room temperature, apply grid line repair material to repair area using the applicator provided with kit.
6. Carefully remove the decal or tape.
NOTE: The grid line repair material must be cured with heat. To avoid heat damage to interior trim, protect the trim near the repair area where heat is to be applied.
IMPORTANT: At least 24 hours are required for complete curing of repair materials. the unit should not be physically disturbed until after that time.
7. Apply heat to repair area for one to two minutes holding heat gun nozzle 25-50 mm (1-2 inches) from surface (Distance A). A minimum temperature of 149 degrees C (300 degrees F) is required.
8. Inspect grid line repair area. If repair appears discolored, apply a coating of tincture of iodine to repair area using a pipe cleaner or fine brush. Allow iodine to dry for about 30 seconds and carefully wipe off excess with lint free cloth.
9. Test rear defogger operation to verify grid line repair.
BUS BAR TERMINAL REPAIR
The rear defogger bus bar terminal can be attached by soldering using solder containing three percent silver and rosin flux paste.
1. Buff area to be repaired with fine steel wool. This removes the oxide coating formed during glass manufacture.
2. Apply the paste-type rosin flux in small quantities to the terminal and bus bar repair area using a brush.
3. The soldering iron tip should be coated with solder beforehand. Use only enough heat to melt the solder and only enough solder to ensure a complete repair.
4. Do not over heat the terminal when soldering it to the bus bar.