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Home › Lexus › 2005 › SC 430 › Repair and Diagnosis › Accessories & Equipment › Heated Glass/Defoggers › Defogger System - Diagnostics › Rear Window Defogger Does Not Operate › Inspection Procedure

Inspection Procedure

  1. PERFORM ACTIVE TEST (REAR WINDOW DEFOGGER WIRE) 
    1. Select the ACTIVE TEST, use the hand-held tester to generate a control command, and then check the rear window defogger wire.

      Luggage room J/B ECU: 

      REAR WINDOW DEFOGGER WIRE

      Item Test Details Diagnostic Note
      DEFOGGER RLY-R Operate rear window defogger wire ON/OFF -

      OK: Rear window defogger wire operates. 

    1. NG: Go to step   2 
    2. OK: REPLACE LUGGAGE ROOM JUNCTION BLOCK ASSY (LUGGAGE ROOM J/B ECU) 
  2. INSPECT FUSE (DEFOG) 
    1. Remove the DEFOG M-fuse from the luggage room J/B.
    2. Measure the resistance of the fuse.

      Standard: Below 1 Ω 

    1. NG: REPLACE FUSE 
    2. OK: Go to next step. 
  3. INSPECT RELAY (Marking: DEFOG) 
    1. Remove the DEFOG relay from the luggage room J/B.
    2. Measure the resistance of the relay.

      Standard: 

      RELAY (MARKING: DEFOG)

      Tester Connection Specified Condition
      3 - 5 10 k ohms or higher
      3 - 5 Below 1 ohms (when battery voltage is applied to terminals 1 and 2)
      Fig 1: Inspecting Relay (DEFOG)
      G02956737Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPLACE RELAY 
    2. OK: Go to next step. 
  4. CHECK WIRE HARNESS (LUGGAGE ROOM J/B ASSY - BATTERY) 
    1. Disconnect the 6L J/B connector.
    2. Measure the voltage of the wire harness side connector.

      Standard: 

      LUGGAGE ROOM J/B ASSY - BATTERY

      Tester Connection Specified Condition
      6L-1 - Body ground 10 to 14 V
      Fig 2: Checking Wire Harness (Luggage Room J/B Assy - Battery)
      G02956738Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 
    2. OK: Go to next step. 
  5. CHECK WIRE HARNESS (LUGGAGE ROOM J/B ASSY - REAR WINDOW DEFOGGER WIRE) 
    1. Disconnect the 6D J/B connector.
    2. Disconnect the R12 defogger connector.
    3. Measure the resistance of the wire harness side connector.

      Standard: 

      LUGGAGE ROOM J/B ASSY - REAR WINDOW DEFOGGER WIRE

      Tester Connection Specified Condition
      6D-1 - R12-1 Below 1 ohms
      6D-1 or R12-1 - Body ground 10 k ohms or higher
      Fig 3: Checking Wire Harness (Luggage From J/B Assy - Rear Window Defogger Wire)
      G02956739Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 
    2. OK: Go to next step. 
  6. CHECK WIRE HARNESS (REAR WINDOW DEFOGGER WIRE - BODY GROUND) 
    1. Disconnect the R13 defogger connector.
    2. Measure the resistance of the wire harness side connector.

      Standard: 

      REAR WINDOW DEFOGGER WIRE - BODY GROUND

      Tester Connection Specified Condition
      R13-1 - Body ground Below 1 ohms
      Fig 4: Checking Wire Harness (Rear Window Defogger Wire - Body Ground)
      G02956740Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 
    2. 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 Fig 5.
      • Fig 5: Wrapping Piece Of Tin Foil Around Tip Of Negative Tester Probe
      G02956741Courtesy 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 Fig 6.

      Standard: 

      VOLTAGE SPECIFIED CONDITION

      Voltage Specified Condition
      Approx. 5 V Wire is not broken
      Approx. 10 or 0 V Wire is broken
      Fig 6: Measuring Voltage At Center Of Each Defogger Wire
      G02956742Courtesy 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.

    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 7: Placing Voltmeter Lead With Battery Side & Ground Side
      G02956743Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    6. Slide the positive (+) lead from the battery side to the ground side.
    7. The point where the voltage jumps 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.

    1. NG: REPAIR REAR WINDOW DEFOGGER WIRE 
    2. OK: Go to next step. 
  8. CHECK OPERATION OF A/C AMPLIFIER ASSY 
    1. After replacing the A/C amplifier with a new one, check that the rear defogger operates normally.

      OK: Rear defogger operates normally. 

    1. NG: Go to  LUGGAGE ROOM J/B ECU POWER SOURCE CIRCUIT   ) 
    2. OK: END (A/C AMPLIFIER ASSY DEFECTIVE) 
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