Defogger System: Inspection

A/C control panel assembly:
INSPECT DEFOGGER SWITCH OPERATION
1. Connect the positive (+) lead from the battery to terminal 17, 18 and negative (-) lead to terminal 40.
2. Connect the positive (+) lead from the battery to terminal 24 through a 1.4 W test bulb.
  
  Fig 1: Checking Indicator Light
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  Fig 2: Continuity Condition Chart
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3. Turn the defogger switch ON and check that the test bulb and indicator light turn ON, then turn OFF after about 15 minutes.
  If operation is not as specified, proceed to the next inspection.
INSPECT DEFOGGER RELAY CONTINUITY

Fig 3: Inspecting Defogger Relay Continuity (1 Of 2)
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Fig 4: Inspecting Defogger Relay Continuity (2 Of 2)
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If continuity is not as specified, replace the relay.
W/ Mirror defogger:
INSPECT MIRROR DEFOGGER OPERATION
1. Connect the positive (+) lead from the battery to terminal 3 and the negative (-) lead to terminal 6.
2. Check that the mirror becomes warm.
HINT:

It will take a short time for the mirror to become warm. If the mirror does not become warm, replace the mirror assembly.

Fig 5: Inspecting Mirror Defogger Operation
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
W/ Mirror defogger and driving position memory: INSPECT MIRROR DEFOGGER OPERATION
1. Connect the positive (+) lead from the battery to terminal 5 and the negative (-) lead to terminal 10.
2. Check that the mirror becomes warm.
HINT:

It will take a short time for the mirror to become warm.

If the mirror does not become warm, replace the mirror assembly.

Fig 6: Inspecting Mirror Defogger Operation
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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, wind a piece of tin foil around the top of the negative probe and press the foil against the wire with your finger, as shown in Fig 7.

Fig 7: Pressing Tin Foil Against Wire

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

Inspect the voltage at the center of each heat wire, as shown in Fig 8.

VOLTAGE CRITERIA

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

Fig 8: Inspecting Voltage At Center Of 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 positive (+) terminal.
Place the voltmeter negative (-) lead with the foil strip against the heat wire at the positive (+) terminal end and slide it toward the negative (-) terminal end.
The point where the voltmeter deflects from zero to several V is the place where the heat wire is broken.

Fig 9: Locating Broken Wire Location

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 is moved to the other end.

IF NECESSARY, REPAIR DEFOGGER WIRE
1. Clean the broken wire tips with a grease, wax and silicone remover.
2. Place the masking tape along both sides of the wire to be repaired.
3. Thoroughly mix the repair agent (Dupont paste No. 4817).
  
  Fig 10: Preparing Repair Point
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Using a fine tip brush, apply a small amount to the wire.
5. After a few minutes, remove the masking tape.
6. Do not use defogger wire for at least 24 hours.
Fig 11: Applying Paste
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