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Defogger System: Inspection

  1. INSPECT DEFOGGER SWITCH CIRCUIT 

    Disconnect the connector from the panel switch and inspect the connector on wire harness side, as shown in Fig 1 .

    Fig 1: Locating Defogger Switch Connector Terminals W/O Navigation & W/Navigation
    G02904405Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    W/O NAVIGATION AND W/NAVIGATION SPECIFIED CONDITION

    Tester connection Condition Specified condition
    B12 (GND) - Ground Constant Continuity
    B11 (+B) - Ground Constant Battery positive voltage
    B22 (IG) - Ground Ignition switch LOCK or ACC No voltage
    B22 (IG) - Ground Ignition switch ON Battery positive voltage
    A10 (RDFGR) - Ground Constant Battery positive voltage
    W/O NAVIGATION AND W/O NAVIGATION SPECIFIED CONDITION

    Tester connection Condition Specified condition
    16 (GND) - Ground Constant Continuity
    8 (IG) - Ground Ignition switch LOCK or ACC No voltage
    8 (IG) - Ground Ignition switch ON Battery positive voltage
    2 (DEFC) - Ground Constant Battery positive voltage

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

    Fig 2: Inspecting Defogger Relay Continuity
    G02904406Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. INSPECT DEFOGGER RELAY CONTINUITY 
    DEFOGGER RELAY SPECIFIED CONDITION

    Condition Tester connection Specified condition
    Constant 1 - 2 Continuity
    Apply B+ between terminals 1 and 2. 3 - 5 Continuity

    If continuity is not as specified, replace the relay.

  3. INSPECT ENGINE ROOM R/B RELAY CIRCUIT (See  INSPECTION  ) 
    Fig 3: Identifying Room R/B Relay
    G02904407Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    HINT:

    The mirror heater relay is built in engine room junction block. Also the relay is constructed with a relay block that is in the junction block as a unit. To disconnect the wire harness connecting with relay block is impossible. If the relay has a malfunction, replace it with junction block assembly wire harness together.

  4. 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  Fig 4  . 
      • Fig 4: Inspecting Defogger Wire
      G02904408Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Turn the ignition switch ON.
    2. Turn the defogger switch ON.
    3. Inspect the voltage at the center of each heat wire, as shown in Fig 5 .
      HEAT WIRE VOLTAGE

      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
      G02904409Courtesy 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.

    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. The point where the voltmeter deflects from several V to 0 V is the place where the defogger wire is broken.
      Fig 6: Measuring Heat Wire Voltage
      G02904410Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    HINT:

    If the heat wire is not broken, the voltmeter indicates 0 V at the positive (+) end of the heat wire but voltage gradually increases to about 12 V as the meter probe moves to the other end.

  5. 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.
    3. Thoroughly mix the repair agent (Dupont paste No. 4817).
      Fig 7: Placing Masking Tape For Repair Along Both Sides Of Wire
      G02904411Courtesy 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.
    6. Do not repair the defogger wire for at least 24 hours.
      Fig 8: Applying Repairing Solvent
      G02904412Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  6. w/ Mirror heater: 
    1. INSPECT MIRROR HEATER OPERATION 
    1. Connect the positive (+) lead from the battery to terminal 5 and the negative (-) lead to terminal 12.
    2. Check that the mirror becomes warm.

    HINT:

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

    Fig 9: Inspecting Mirror Heater Operation
    G02904413Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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