On-Vehicle Inspection

INSPECT BACK WINDOW GLASS (DEFOGGER WIRE)

NOTE:

When cleaning the glass, wipe the glass along the wire using a soft, dry cloth. Take care not to damage the defogger wires.
Do not use detergents or glass cleaners that have abrasive ingredients.
When measuring voltage, wrap a piece of tin foil around the tip of the negative (-) tester probe and press the foil against the wire with your finger, as shown below.

Fig 1: Wrapping Piece Of Tin Foil Around Tip Of Negative (-) Tester Probe

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Turn the engine switch on (IG).
Turn the defogger switch on.

Measure the voltage at the center of each defogger wire as shown below.

Standard voltage

VOLTAGE SPECIFICATION TABLE

Voltage	Criteria
Approx. 5 V	Wire is not broken
Approx. 10 or 0 V	Wire is broken

Fig 2: Measuring Voltage At Center Of Defogger Wire

HINT:

If there is approximately 10 V, the wire may be faulty between the center of the wire and the wire end on the battery side. If there is no voltage, the wire may be faulty between the center of the wire end and the wire end on the ground side.

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

Fig 3: Identifying Faulty Wire Between Center Of Wire & Wire End On Battery Side
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Slide the positive (+) lead from the battery side to the ground side.
The point where the voltage drops from approximately 10 V to 0 V is where the defogger wire is broken.
HINT:

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