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Defogger System: Inspection

WARNING: This page is about a different car, the 2002 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.
  1. Inspect defogger timer operation  :
    1. Connect the positive (+) lead from the voltmeter to terminal 1,2 and 14 of panel switch connector and negative (-) lead to terminal 10.
      Fig 1: Testing Defogger Timer
      G01896075Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. When the switch is OFF, the voltage should be approx. 12V.
    3. Turn the defogger switch ON and check that the indicator lights up and that the voltage is less than 1 V.
      Fig 2: Locating Defogger Indicator Light
      G01896076Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    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.

  2. Inspect defogger switch located in integration control panel switch circuit (connector disconnected):

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

    Fig 3: Identifying Defogger Switch Connector Terminals (Wire Harness Side)
    G01896077Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 4: Defogger Switch Connector Terminal Specifications
    G01896078Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    If the circuit is not as specified, replace the switch.

  3. Inspect defogger relay continuity  :
    Fig 5: Identifying Defogger Relay Terminals
    G01896080Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 6: Defogger Relay Terminal Specifications
    G01896079Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    If continuity is not as specified, replace the relay.

  4. Inspect defogger relay circuit  . See FUSES & CIRCUIT BREAKERS .
  5. Inspect mirror heater relay continuity  :
    Fig 7: Identifying Mirror Heater Relay Terminals
    G01896082Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 8: Mirror Heater Relay Terminal Specifications
    G01896081Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    If continuity is not as specified, replace the relay.

  6. Inspect mirror heater relay circuit  . See FUSES & CIRCUIT BREAKERS .
    7. CAUTION:
    • 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.
      Fig 9: Procedure For Probing Defogger Wire
      G01896083Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  7. Inspect defogger wire  :
    1. Turn the ignition switch ON.
    2. Turn the defogger switch ON.
      3. NOTE: 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.
      Fig 10: Identifying Defogger Wire Probing Points
      G01896085Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Fig 11: Defogger Wire Specifications Chart
      G01896084Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Inspect the voltage at the center of each heat wire.
    4. Place the voltmeter positive (+) lead against the defogger wire on the battery side.
    5. Place the voltmeter negative (-) lead with the foil strip against the wire on the ground side.
    6. Slide the positive (+) lead from battery to ground side.
      7. 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 moves to the other end.
      Fig 12: Locating Defogger Wire Break Points
      G01896086Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    7. The point where the voltmeter deflects from several V to zero V is the place where the defogger wire is broken.
  8. If necessary, repair defogger wire  :
    1. Clean the broken wire tips with grease, wax and silicone remover.
    2. Place the masking tape along both sides of the wire for repair.
      Fig 13: Repairing Defogger Wire
      G01896087Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Thoroughly mix the repair agent (Dupont paste No. 4817).
    4. Using a fine tip brush, apply a small amount of the agent to the wire.
      Fig 14: Applying Repair Agent
      G01896088Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    5. After a few minutes, remove the masking tape.
    6. Do not repair the defogger wire for at least 24 hours.
  9. Inspect mirror heater operation  :
    1. Connect the positive (+) lead from the battery to terminal 6 and the negative (-) lead to terminal 4.
      Fig 15: Testing Mirror Heater & Identifying Terminals
      G01896089Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      2. NOTE: It will take a short time for the mirror to become warm.
    2. Check that the mirror becomes warm.
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