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Home >> Lexus >> 2008 >> SC 430 >> Repair and Diagnosis >> Body & Frame >> Windows >> Windshield/WINDOWGLASS >> Window Defogger System >> Rear Window Defogger System does not Operate >> Inspection Procedure
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Inspection Procedure

  1. PERFORM ACTIVE TEST BY TECHSTREAM (REAR WINDOW DEFOGGER WIRE) 
    1. Select the Active Test, use the Techstream to generate a control command, and then check the rear window defogger wire.

      Body No. 4 

      ACTIVE TEST - BODY NO. 4

      Tester Display Test Part Control Range Diagnostic Note
      Rear Defogger Operate rear window defogger wire OFF or ON -

      OK: Rear window defogger wire operates. 

    OK: REPLACE LUGGAGE ROOM JUNCTION BLOCK ASSEMBLY (LUGGAGE ROOM JUNCTION BLOCK ECU) 

    NG: Go to Next Step 

  2. INSPECT FUSE (DEFOG) 
    1. Remove the DEFOG M-fuse from the luggage room junction block.
    2. Measure the resistance of the fuse.

      Standard resistance: Below 1 Ω 

    NG: REPLACE FUSE 

    OK: Go to Next Step 

  3. INSPECT DEFOGGER RELAY (Marking: DEFOG) 
    1. Remove the DEFOG relay from the luggage room junction block.
    2. Measure the resistance of the relay.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      3 - 5 10 kΩ or higher
      3 - 5 Below 1 Ω (when battery voltage is applied to terminals 1 and 2)
      Fig 1: Identifying Defogger Relay Terminals
      G05293509Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE DEFOG RELAY 

    OK: Go to Next Step 

  4. CHECK WIRE HARNESS (LUGGAGE ROOM JUNCTION BLOCK - BATTERY) 
    1. Disconnect the 6L junction block connector.
    2. Measure the voltage of the wire harness side connector.
      Fig 2: Identifying Wire Harness Side
      G05293510Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      6L-1 - Body ground 10 to 14 V

    NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

    OK: Go to Next Step 

  5. CHECK WIRE HARNESS (LUGGAGE ROOM JUNCTION BLOCK - REAR WINDOW DEFOGGER WIRE) 
    Fig 3: Identifying Luggage Room Junction Block Connector Terminals And Rear Window Defogger Wire Connector Terminals
    G05293511Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the 6D junction block connector.
    2. Disconnect the R12 defogger connector.
    3. Measure the resistance of the wire harness side connectors.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      6D-1 - R12-1 Below 1 Ω
      6D-1 or R12-1 - Body ground 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

    OK: Go to Next Step 

  6. CHECK WIRE HARNESS (REAR WINDOW DEFOGGER WIRE - BODY GROUND) 
    1. Disconnect the R13 defogger connector.
      Fig 4: Identifying R13 Defogger Connector Terminals
      G05293512Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance of the wire harness side connector.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      R13-1 - Body ground Below 1 Ω

    NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

    OK: Go to Next Step 

  7. INSPECT REAR WINDOW DEFOGGER WIRE 
    NOTE:
    • When cleaning the glass, wipe the glass along the wire using a soft and dry cloth. Take care not to damage the 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 5: Identifying Rear Window Defogger Wire
      G05293513Courtesy 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 

      STANDARD VOLTAGE REFERENCE CHART

      Voltage Criteria
      Approx. 5 V Wire is not broken
      Approx. 10 or 0 V Wire is broken
      Fig 6: Measuring Voltage Center Of Defogger Wire
      G05293514Courtesy 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 and the wire end on the ground side.

      Fig 7: Measuring Voltage Between Center Of Wire And Wire End On Ground Side
      G05293515Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    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.
    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 should indicate 0 V at the positive (+) end of the defogger wire. The voltage gradually increases to approximately 12 V as the lead moves to the other end.

    NG: REPAIR REAR WINDOW DEFOGGER WIRE 

    OK: Go to Next Step 

  8. CHECK OPERATION OF A/C AMPLIFIER ASSEMBLY 
    1. After replacing the A/C amplifier with a new one, check that the rear defogger operates normally.

      OK: Rear defogger operates normally. 

    NG: GO TO LUGGAGE ROOM JUNCTION BLOCK ECU POWER SOURCE CIRCUIT 

    OK: END (A/C AMPLIFIER ASSEMBLY DEFECTIVE)