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Defogger System: Inspection

WARNING: This page is about a different car, the 2002 Toyota 4Runner. However, it is still accessible from the selected car via links, so may be relevant.
  1. Inspect defogger switch continuity  :

    Push the defogger switch and check that continuity exists between terminals 7 and 10.

    Fig 1: Identifying Defogger Switch Terminals & Switch Positions
    G01908896Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    If the continuity is not as specified, replace the integration control panel.

  2. Inspect defogger relay continuity  :
    Fig 2: Identifying Defogger Relay Terminals
    G01908898Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 3: Defogger Relay Specifications Chart
    G01908897Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    If the continuity is not as specified, replace the relay.

    3. NOTE:
    • When cleaning the glass, use a soft and dry cloth, and wipe the glass in the moving 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.
      Fig 4: Procedure For Probing Defogger Wire
      G01908899Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. Inspect defogger wire  :
    1. Turn the ignition switch ON.
    2. Turn the defogger switch ON.
      3. NOTE: If the voltage 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.
      Fig 5: Explaining Causes Of Possible Voltage Readings
      G01908902Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Fig 6: Identifying Defogger Wire Probing Points
      G01908901Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Fig 7: Defogger Wire Specifications Chart
      G01908900Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Inspect the voltage at the center of each heat wire, as shown.
    4. Place the voltmeter positive (+) lead against the defogger positive (+) terminal.
    5. 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.
      6. NOTE: 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.
    6. The point where the voltmeter deflects between zero and several V is the place where the heat wire is broken.
  4. If necessary, repair defogger wire  :
    1. Clean the broken wire tips with grease, wax and silicone remover.
      Fig 8: Repairing Defogger Wire
      G01908903Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Place the masking tape along both sides of the wire to be repaired.
    3. Thoroughly mix the repair agent (Dupont paste No. 4817 or equivalent).
    4. Using a fine tip brush, apply a small amount of the agent to the wire.
      Fig 9: Applying Repair Agent
      G01908904Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    5. After a few minutes, remove the masking tape.
    6. Do not repair the defogger wire for at lease 24 hours.
  5. Inspect mirror defogger operation  :
    1. Connect the positive (+) lead from the battery to terminal 3 and the negative (-) lead to terminal 2.
      Fig 10: Identifying Mirror Defogger Terminals
      G01908905Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      2. NOTE: It takes a little time for the mirror to become warm.
    2. Check that the mirror becomes warm.
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