Minor wire breaks can be repaired without removing the rear window from the vehicle.
Check the rear window heater as follows:
To detect a break in the rear defroster wire, turn on the ignition and the rear defroster switch.
Connect one voltmeter lead to the positive terminal of the heater and the other to «mass» contact. If the voltmeter does not show voltage, check the fuse protecting the heater electrical circuit. If voltage is applied to the heater terminals, perform the following checks.
Pic. 15.44. Using a foil-wrapped voltmeter probe to detect a broken rear window defroster wire
Connect one voltmeter lead to «weight» car, and wrap the second probe with foil and move the foil along the heater conductor (see fig. 15.44).
Pic. 15.45. Using a Voltmeter to Locate a Broken Rear Defroster Wire
Connect a voltmeter lead to the center of each rear defroster wire. If the voltmeter shows a voltage of about 5.5 V, then the heater conductor is good. If the voltmeter shows a voltage of 0 V or 12 V, then there is a break in the heater conductor (pic. 15.45).
Pic. 15.46. Using a voltmeter to locate a break in the rear window defroster conductor
To locate a break in the heater conductor, connect one voltmeter probe to the positive terminal of the heater, and move the second probe along the heater conductor from the negative terminal of the heater. The point at which the voltage shown by the voltmeter drops from a few volts to zero will be the location of the break in the heater conductor (pic. 15.46).
Before repairing the heater, turn it on for a few minutes.
Repair the rear window heater as follows:
Repair the gap using a special repair kit.
Strip the conductors on both sides of the conductor break and degrease them.
Use adhesive tape to seal the glass on both sides of the conductor at the point of its rupture.
Prepare the conductive adhesive from the repair kit.
Apply conductive adhesive to the break and undamaged areas of each conductor for a distance of 18 mm.
Dry the conductive adhesive for 24 hours, then remove the adhesive tape.