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DTC C123A-1C: Supply Voltage Circuit Voltage Out of Range [12/2019 - 11/2023]: Procedure

  1. CHECK HARNESS AND CONNECTOR (IG1 TERMINAL) 
    1. Disconnect the M41 4WD ECU assembly connector.
      GTY940851Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to 4WD ECU Assembly)
    2. Turn the ignition switch to ON.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      M41-24 (IG1) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (GND TERMINAL) 
    1. Disconnect the M41 4WD ECU assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      M41-1 (GND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE 4WD ECU ASSEMBLY 

    Refer to REMOVAL [12/2019 - ]

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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