2008 Lexus SC 430FACTORY OEM SERVICE PROCEDURE

Inspection Procedure

WARNING: This page is about a different car, the 2007 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.
  1. INSPECT FUSE (RADIO NO. 2, AM1, TV) 
    1. Remove the RADIO NO. 2 and TV fuses from the passenger side junction block.
    2. Remove the AM1 fuse from the driver side junction block.
    3. Measure the resistance of the fuses.

      Standard resistance: 

      Below 1 Ω 

      NG: REPLACE FUSE 

      OK: Go to next step 

  2. INSPECT RELAY (Marking: ACC) 
    1. Remove the ACC relay from the passenger side junction block.
    2. Measure the resistance of the relay.
      Fig 1: Measuring Resistance Between Relay Terminals
      G05293363Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Specified Condition
      3 - 5 Below 1 Ω
      3 - 5 10 kΩ or higher (when battery voltage is applied to terminals 1 and 2)

    NG: REPLACE RELAY 

    OK: Go to next step 

  3. CHECK WIRE HARNESS (NAVIGATION ECU - BATTERY AND BODY GROUND) 
    1. Disconnect the N3 and N7 ECU connectors.
      Fig 2: Identifying N3 And N7 ECU Connectors Terminals
      G05293364Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance and voltage of the wire harness side connectors.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Specified Condition
      N3-17 (GND1) - Body ground Below 1 Ω
      N7-7 (SNSE) - Body ground Below 1 Ω

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      N3-18 (ACC) - Body ground Ignition switch ACC 10 to 14 V
      N3-9 (+B) - Body ground Always 10 to 14 V

    NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

    OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE OR DIAGNOSTIC TROUBLE CODE CHART 

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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.