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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System (W/O AFS) - Symptom Tests & Circuit Tests (2 Of 2) >> LIGHTING SYSTEM (w/o AFS) >> Back-up Light Circuit [12/2019 - 11/2023] >> Procedure

Back-up Light Circuit [12/2019 - 11/2023]: Procedure

  1. CHECK FOR DTC 
    1. Check for DTCs.

      Powertrain > Hybrid Control > Trouble Codes 

      Result

      Result Proceed to
      Hybrid control system DTCs are not output A
      Hybrid control system DTCs are output B

    Result: 

    B 

    GO TO HYBRID CONTROL SYSTEM 

    For 2WD: Refer to DIAGNOSTIC TROUBLE CODE CHART [12/2019 - 09/2020] , or refer to DIAGNOSTIC TROUBLE CODE CHART [09/2020 - 10/2021] , or refer to DIAGNOSTIC TROUBLE CODE CHART [10/2021 - 11/2023]

    For AWD: Refer to DIAGNOSTIC TROUBLE CODE CHART [12/2019 - 09/2020] , or refer to DIAGNOSTIC TROUBLE CODE CHART [09/2020 - 10/2021] , or refer to DIAGNOSTIC TROUBLE CODE CHART [10/2021 - 11/2023]

    Result: 

    A 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BODY GROUND) 
    1. Disconnect the 4B instrument panel junction block assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      4B-3 - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY) 
    1. Disconnect the A31 hybrid vehicle control ECU connector.
    2. Disconnect the 4C instrument panel junction block assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A31-20 (BL) - 4C-19 Always Below 1 Ω
      A31-20 (BL) or 4C-19 - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK HYBRID VEHICLE CONTROL ECU (OUTPUT VOLTAGE) 
    GTY870785Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Component with harness connected
    (Instrument Panel Junction Block Assembly)
    1. Connect the A31 hybrid vehicle control ECU connector.
    2. Connect the 4B and 4C instrument panel junction block assembly connectors.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      4C-19 - Body ground Ignition switch off, reverse (R) not selected Below 1 V
      4C-19 - Body ground Ignition switch ON, reverse (R) selected 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

    Result: 

    OK 

    See step  5

  5. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (OUTPUT VOLTAGE) 
    GTY933355Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Component with harness connected
    (Instrument Panel Junction Block Assembly)
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      4D-10 - Body ground Ignition switch off, reverse (R) not selected Below 1 V
      4D-10 - Body ground Ignition switch ON, reverse (R) selected 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    NG 

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

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