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.

Prepare the following checking items.
- Liquid crystal thermograph sheet (Approximate Size: 300 x 300 mm (11.8 x 11.8 in) and thermal temperature: 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 from the outside of the rear glass.
NOTE: Use the liquid crystal thermograph sheet every range it is separated with the separate line.

Fig 1: Identifying Liquid Crystal Thermograph Sheet And Separate Line
Courtesy of SUBARU OF AMERICA, INC.

Determine the faulty heat wire by checking the color of the liquid crystal thermograph sheet.

Liquid crystal thermograph sheet	Criteria
Change occurred (red → blue)	Normal
No change (black)	Open

NOTE:

Check from the inside of the glass if the liquid crystal thermograph sheet does not change.
The time for the color change may differ depends on the surface temperature of the glass.

Wrap a piece of aluminum foil around the tip of tester probe and press it against the heat wire with your finger.

Fig 2: Pressing 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.
Move the tester probe on the negative (-) side slowly along the heat wire. If voltage changes from zero to several volts during movement of tester probe, heat wire is open at the voltage change point.

Fig 3: Measuring Voltage Between Antenna Wire Center And Positive Terminal Of Probe
Courtesy of SUBARU OF AMERICA, INC.
Repair the heat wire that determines the place of the open circuit. Refer to , REPAIR , Rear Window Defogger System.