2004 Lexus LS 430FACTORY OEM SERVICE PROCEDURE

Section 331 (Defogger System): Inspection

WARNING: This page is about a different car, the 2003 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.
  1. INSPECT DEFOGGER SWITCH CIRCUIT 

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

    Fig 1: Inspecting Defogger Switch Circuit
    G03375536Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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    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

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    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.

  2. INSPECT DEFOGGER RELAY CONTINUITY 
    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.

    Fig 2: Inspecting Defogger Relay Continuity
    G03375537Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. MIRROR HEATER RELAY: INSPECT ENGINE ROOM R/B RELAY CIRCUIT (See  INSPECTION  ) 

    HINT:

    The mirror heater relay is built in the 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 the junction block assembly wire harness together.

    Fig 3: Identifying Engine Built In Relay
    G03375538Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  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 fingers, as shown. 
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