2007 Lexus SC 430FACTORY OEM SERVICE PROCEDURE

Inspection Procedure

  1. INSPECT FUSE (MPX-B1, AM1, MPX-IG, D-DOOR, D/C CUT) 
    1. Remove the MPX-IG and AM1 fuses from the driver side junction block.
    2. Remove the MPX-B1 fuse from the passenger side junction block.
    3. Remove the D-DOOR and D/C CUT fuses from the engine room No. 1 relay block.
    4. Measure the resistance of the fuses.

      Standard resistance: Below 1 Ω 

    NG: REPLACE FUSE 

    OK: Go to Next Step 

  2. INSPECT RELAY (Marking: IG1) 
    1. Remove the IG1 relay from the driver side junction block.
    2. Measure the resistance of the relay.
      Fig 1: Measuring Resistance Of Relay
      G05293448Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      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)

    NG: REPLACE RELAY 

    OK: Go to Next Step 

  3. CHECK WIRE HARNESS (DOOR ECU FRONT LH - BATTERY AND BODY GROUND) 
    1. Disconnect the D19 ECU connector.
      Fig 2: Identifying D19 ECU Connector Terminals
      G05293449Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance and voltage of the wire harness side connector.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Condition Specified Condition
      D19-1 (GND) - Body ground Always Below 1 Ω

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Condition Specified Condition
      D19-4 (CPUB) - Body ground Always 10 to 14 V
      D19-6 (BDR) - Body ground Always 10 to 14 V
      D19-5 (SIG) - Body ground Ignition switch ON 10 to 14 V

    NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

    OK: REPLACE MULTIPLEX NETWORK DOOR ECU FRONT LH 

Factory Service Tools

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When to See a Mechanic

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.
  • • You are not confident in the next step or safety outcome.