On-Vehicle Inspection

INSPECT WINDOW DEFOGGER WIRE

NOTE:

When cleaning the glass, use a soft, dry cloth, and wipe the glass in the direction of the wire. Take care not to damage the wires.
Do not use detergents or glass cleaners with abrasive ingredients.
When measuring voltage, wrap a piece of tin foil around the tip of the negative probe and press the foil against the wire with your finger, as shown in the illustration.

Fig 1: Wrapping Piece Of Tin Foil Around Tip Of Negative Probe
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Turn the ignition switch ON.
Turn the defogger switch ON.

Inspect the voltage at the center of each heat wire, as shown.

VOLTAGE AND CRITERIA REFERENCE

Voltage	Criteria
Approx. 5 V	Okay (No break in wire)
Approx. 10 V or 0 V	Broken wire

Fig 2: Inspecting Voltage At Center Of Each Heat Wire

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

If there is approximately 10 V, the wire is broken between the center of the wire and the positive (+) end. If there is no voltage, the wire is broken between the center of the wire and ground.

Place the voltmeter positive (+) lead against the defogger wire on the battery side.
Place the voltmeter negative (-) lead with the foil strip against the wire on the ground side.
Slide the positive (+) lead from the battery to the ground side.

Fig 3: Measuring Heat Wire Voltage

The point where the voltmeter deflects from several V to zero V is the place where the defogger wire is broken.
HINT:

If the heat wire is not broken, the voltmeter indicates 0 V at the positive (+) end of the heat wire but gradually increases to about 12 V as the meter probe moves to the other end.