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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 61 (Hybrid Control System (2WD) - Diagnostic Codes (7 Of 7) & Circuit Tests) >> HYBRID CONTROL SYSTEM (for 2WD) >> Inverter Low-voltage Circuit [12/2019 - 11/2023] >> Procedure

Inverter Low-voltage Circuit [12/2019 - 11/2023]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FUSE (PCU) 
    1. Remove the PCU fuse from the No. 5 floor relay block and No. 5 floor junction block assembly.
      GTY895821Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 5 Floor Relay Block and No. 5 Floor Junction Block Assembly
      *2 PCU Fuse
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      PCU fuse Always Below 1 Ω
    3. Install the PCU fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  5

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY POWER SOURCE CIRCUIT) 
    WARNING:

    Be sure to wear insulated gloves.

    1. Check that the service plug grip is not installed.
      NOTE:

      After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the repair information because this may cause a malfunction.

    2. Disconnect the A55 inverter with converter assembly connector.
    3. Measure the resistance according to the value(s) in the table below.
      GTY876562Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Inverter with Converter Assembly)

      Standard Resistance

      Tester Connection Condition Specified Condition
      A55-9 (GND1) - Body ground Ignition switch off Below 1 Ω
      A55-8 (GND2) - Body ground Ignition switch off Below 1 Ω
    4. Connect the cable to the negative (-) auxiliary battery terminal.
    5. Turn the ignition switch to ON.
    6. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A55-36 (+B) - Body ground Ignition switch ON Same as auxiliary battery voltage
      A55-35 (+B2) - Body ground Ignition switch ON Same as auxiliary battery voltage
      NOTE:

      Turning the ignition switch to ON with the inverter with converter assembly connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

    7. Turn the ignition switch off.
    8. Disconnect the cable from the negative (-) auxiliary battery terminal and wait for 2 minutes or more.
    9. Reconnect the A55 inverter with converter assembly connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE POWER SOURCE CIRCUIT 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - INVERTER WITH CONVERTER ASSEMBLY) 
    WARNING:

    Be sure to wear insulated gloves.

    1. Check that the service plug grip is not installed.
      NOTE:

      After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the repair information because this may cause a malfunction.

    2. Disconnect the A55 inverter with converter assembly connector.
    3. Disconnect the A31 hybrid vehicle control ECU connector.
    4. Measure the resistance according to the value(s) in the table below.
      GTY878638Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Inverter with Converter Assembly)
      *b Front view of wire harness connector
      (to Hybrid Vehicle Control ECU)

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      A55-3 (HMCH) - A31-4 (HMCH) Ignition switch off Below 1 Ω
      A55-4 (HMCL) - A31-14 (HMCL) Ignition switch off Below 1 Ω

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition
      A55-3 (HMCH) or A31-4 (HMCH) - Body ground and other terminals Ignition switch off 10 kΩ or higher
      A55-4 (HMCL) or A31-14 (HMCL) - Body ground and other terminals Ignition switch off 10 kΩ or higher
    5. Connect the cable to the negative (-) auxiliary battery terminal.
    6. Turn the ignition switch to ON.
    7. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A55-3 (HMCH) or A31-4 (HMCH) - Body ground and other terminals Ignition switch ON Below 1 V
      A55-4 (HMCL) or A31-14 (HMCL) - Body ground and other terminals Ignition switch ON Below 1 V
      NOTE:

      Turning the ignition switch to ON with the hybrid vehicle control ECU and inverter with converter assembly connectors disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

    8. Turn the ignition switch off.
    9. Disconnect the cable from the negative (-) auxiliary battery terminal and wait for 2 minutes or more.
    10. Reconnect the A31 hybrid vehicle control ECU connector.
    11. Reconnect the A55 inverter with converter assembly connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK HYBRID VEHICLE CONTROL ECU 
    1. Disconnect the A31 hybrid vehicle control ECU connector.
    2. Measure the resistance according to the value(s) in the table below.
      GTY888625Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Hybrid Vehicle Control ECU)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      A31-14 (HMCL) - A31-4 (HMCH) Ignition switch off 80 to 170 Ω
    3. Reconnect the A31 hybrid vehicle control ECU connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    INVERTER LOW-VOLTAGE CIRCUIT NORMAL (PERFORM NEXT STEP FOR REFERENCED DTC) 

    Result: 

    NG 

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

  5. CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - PCU FUSE) 
    WARNING:

    Be sure to wear insulated gloves.

    1. Check that the service plug grip is not installed.
      NOTE:

      After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the repair information because this may cause a malfunction.

    2. Disconnect the A55 inverter with converter assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A55-36 (+B) - Body ground Ignition switch off 10 kΩ or higher
      A55-35 (+B2) - Body ground Ignition switch off 10 kΩ or higher
      GTY876564Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Inverter with Converter Assembly)
    4. Reconnect the A55 inverter with converter assembly connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  6

  6. REPLACE INVERTER WITH CONVERTER ASSEMBLY 

    Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    REPLACE FUSE (PCU) 

  7. REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    REPLACE FUSE (PCU) 

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