On-Vehicle Inspection

INSPECT DEFOGGER TIMER OPERATION (Connector connected)
1. Connect the positive (+) lead from the voltmeter to terminals 1, 2 and 7 of the panel switch connector and the negative (-) lead to terminal 10.
2. When the switch is OFF, the voltage should be approx. 12 V.
3. Turn the defogger switch ON and check that the indicator comes on and that the voltage is less than 1 V.
4. After 15 minutes, check that the switch is OFF and the voltage is approx. 12 V.
  If operation is not as specified, replace the switch.

INSPECT DEFOGGER SWITCH CIRCUIT (IN INTEGRATION CONTROL PANEL SWITCH)

Disconnect the connector from the panel switch and inspect the connector on the harness side, as shown in the chart below.

Fig 3: Identifying Defogger Switch Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DEFOGGER SWITCH CONNECTOR TERMINALS SPECIFIED CONDITION

Tester connection	Condition	Specified condition
10 - Ground	Always	Continuity
1 - Ground	Always	Battery voltage
2 - Ground	Ignition switch OFF or ACC	No voltage
2 - Ground	Ignition switch ON	Battery voltage
7 - Ground	Ignition switch OFF	No voltage
7 - Ground	Ignition switch ACC or ON	Battery voltage

If the circuit is not as specified, inspect the circuit connected to other parts.

INSPECT 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 4: 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 SPECIFIED CONDITIONS

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

Fig 5: Inspecting Voltage At Center Of Each Heat Wire

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.
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 12v as the meter probe moves to the other end.

Fig 6: Measuring Heat Wire Voltage
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002