2009 Scion tC AutomaticFACTORY OEM SERVICE PROCEDURE

Window Defogger System: Inspection

  1. INSPECT BACK DOOR 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 in the illustration.
      Fig 1: Pressing Foil With Finger
      G05541827Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Turn the ignition switch ON.
    2. Turn the defogger switch ON.
    3. Measure the voltage at the center of each defogger wire as shown in the illustration.

      Standard voltage 

      VOLTAGE SPECIFICATION

      Voltage Criteria
      Approx. 5 V Wire is not broken
      Approx. 10 or 0 V Wire is broken
      Fig 2: Identifying Voltage At Center Of Each Defogger Wire
      G05541828Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      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.

    4. Place the voltmeter's positive (+) lead against the defogger wire on the battery side.
    5. Place the voltmeter's negative (-) lead with the foil strip against the wire on the ground side.
      Fig 3: Identifying Voltage Of Defogger Wire
      G05541829Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    6. Slide the positive (+) lead from the battery side to the ground side.
    7. 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.

    8. If necessary, repair the defogger wire.
      1. Clean the broken wire tips with grease, wax and silicone remover.
      2. Place masking tape along both sides of the wire.
      3. Thoroughly mix the repair agent.

        Dupont paste: 

        No. 4817 or equivalent 

        Fig 4: Identifying Masking Tape Along Both Sides Of Wire
        G04952253Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      4. Using a fine tip brush, apply a small amount of the agent to the wire.
      5. After a few minutes, remove the masking tape.
        NOTE: Do not repair the defogger wire again for at least 24 hours.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
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