Heat Wire Inspection

CAUTION: Use a dry soft cloth to wipe off dirt on the glass along the heat wires with care not to damage the heat wires.

Inspect the following inspection tools.
- Liquid crystal thermograph sheet (size: approx. 300 x 300 mm (11.8 x 11.8 in), heat sensing temperature: approx. 35 - 40°C (95 - 104°F))
- Aluminum foil
Turn the ignition switch to ON.
Turn the defogger switch to ON.
Push the liquid crystal thermograph sheet on to the outer surface of the rear glass.

Fig 1: Identifying Liquid Crystal Thermograph Sheet On Outer Surface Of Rear Glass
Courtesy of SUBARU OF AMERICA, INC.

NOTE: Use the liquid crystal thermograph sheet to each section divided by parting lines.

Check the color of the liquid crystal thermograph sheet to identify the faulty heat wire.

LIQUID CRYSTAL THERMOGRAPH SHEET OPERATION CHART

Liquid crystal thermograph sheet	Criteria
Changed (red → blue)	Normal operation
No change (black)	Open

NOTE:

If the response of the liquid crystal thermograph sheet is not sufficient, try the inspection on the inner surface of the glass.
The time until color change depends on the glass surface temperature.

Wrap the aluminum foil around the tip of each tester probe and push them on to the faulty heat wire.

Fig 2: Pushing Aluminum Foil Using Tester Probe
Courtesy of SUBARU OF AMERICA, INC.
To both ends of the section that has been found to include an open in the step 5), apply the tester positive (+) probe and the negative (-) probe.
Slowly move the negative (-) tester probe along the heat wire. While moving the tester probe, find an open point where the voltage reading changes from 0.

Fig 3: Applying Tester Positive Probe And Negative Probe
Courtesy of SUBARU OF AMERICA, INC.
Repair the heat wire that determines the place of the open circuit. Ref. to REPAIR , Rear Window Defogger System.