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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 113 (Hybrid Control System (2WD) - Diagnostic Codes (6 Of 7)) >> HYBRID CONTROL SYSTEM (for 2WD) >> DTC P3123-87: Lost Communication with Drive Motor Control Module "A" from Hybrid/EV Control Module Missing Message [12/2019 - 11/2023] >> Procedure

DTC P3123-87: Lost Communication with Drive Motor Control Module "A" from Hybrid/EV Control Module Missing Message [12/2019 - 11/2023]: Procedure

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

      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  9

    Result: 

    OK 

    See step  2

  2. CLEAR DTC 

    Refer to PROCEDURE - Step 3

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    See step  3

  3. CHECK DIAGNOSIS RELATED INFORMATION AND DTC OUTPUT (HYBRID CONTROL) 
    1. Turn the ignition switch to ON and wait for 2 minutes or more.
    2. Check for Diagnosis Related Information and DTCs.

      Powertrain > Hybrid Control > Utility 

      Tester Display
      Diagnosis Related Information

      Powertrain > Hybrid Control > Trouble Codes 

      Result

      Result  Proceed to
      P3123-87 is listed in Diagnosis Related Information or DTC P3123-87 is output. A
      P3123-87 is not listed in Diagnosis Information and DTC P3123-87 is not output. B
    3. Turn the ignition switch off.

    Result: 

    B 

    CHECK FOR INTERMITTENT PROBLEMS 

    Refer to CHECK FOR INTERMITTENT PROBLEMS [12/2019 - 11/2023]

    Result: 

    A 

    See step  4

  4. CHECK CONNECTOR CONNECTION CONDITION (HYBRID VEHICLE CONTROL ECU CONNECTOR) 

    Refer to PROCEDURE - Step 1

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    CONNECT SECURELY 

    Result: 

    OK 

    See step  5

  5. CHECK CONNECTOR CONNECTION CONDITION (INVERTER WITH CONVERTER ASSEMBLY CONNECTOR) 

    Refer to PROCEDURE - Step 3

    Result

    Result Proceed to
    OK A
    NG (The connector is not connected securely.) B
    NG (The terminals are not making secure contact or are deformed, or water or foreign matter exists in the connector.) C

    Result: 

    B 

    CONNECT SECURELY 

    Result: 

    C 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    A 

    See step  6

  6. 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.

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

    3. Measure the resistance according to the value(s) in the table below.
      GTY876563Courtesy 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 11 to 14 V
      A55-35 (+B2) - Body ground Ignition switch ON 11 to 14 V
      NOTE:

      Turning the ignition switch to ON with the inverter with converter assembly 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.
    9. 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  7

  7. CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - HYBRID VEHICLE CONTROL ECU) 
    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. 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.
      GTY878643Courtesy 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 Voltage

      Tester Connection Condition Specified Condition
      A31-14 (HMCL) - Body ground Ignition switch ON Below 1 V
      A31-4 (HMCH) - Body ground Ignition switch ON Below 1 V
      NOTE:

      Turning the ignition switch to ON with the hybrid vehicle control ECU connector and the inverter with converter assembly 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.
    9. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

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

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition
      A55-4 (HMCL) or A31-14 (HMCL) - Body ground and other terminals Ignition switch off 10 kΩ or higher
      A55-3 (HMCH) or A31-4 (HMCH) - Body ground and other terminals Ignition switch off 10 kΩ or higher

      HINT: 

      As there might be an intermittent malfunction, inspect the following items even if the measured resistance is as specified.

      Check that each connector between the inverter with converter assembly and hybrid vehicle control ECU is not loose or disconnected.

    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  8

  8. CHECK HYBRID VEHICLE CONTROL ECU 
    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.
      GTY894634Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU)      		 - -

      Standard Resistance

      Tester Connection Condition Specified Condition
      A31-14 (HMCL) - A31-4 (HMCH) Ignition switch off 110 to 130 Ω
    4. Reconnect the A55 inverter with converter assembly connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE INVERTER WITH CONVERTER ASSEMBLY 

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

    Result: 

    NG 

    REPLACE HYBRID VEHICLE CONTROL ECU 

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

  9. REPLACE FUSE (PCU) 
    1. Replace the PCU fuse.
      GTY895821Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 5 Floor Relay Block and No. 5 Floor Junction Block Assembly
      *2 PCU Fuse
    2. Turn the ignition switch to ON (READY).
    3. Check if there is an open circuit in the PCU fuse in the No. 5 floor relay block and No. 5 floor junction block assembly.

      OK

      There is no open circuit in the PCU fuse.

      HINT: 

      If the fuse does not become open again after turning the ignition switch to ON (READY), it can be assumed that the previous fuse failed due to age.

    4. Turn the ignition switch off.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    END 

    Result: 

    NG 

    See step  10

  10. 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. Remove the PCU fuse from the No. 5 floor relay block and No. 5 floor junction block assembly.
    3. Disconnect the A55 inverter with converter assembly connector.
    4. Measure the resistance according to the value(s) in the table below.
      GTY902580Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 5 Floor Relay Block and No. 5 Floor Junction Block Assembly *2 PCU Fuse Holder
      *a Front view of wire harness connector
      (to Inverter with Converter Assembly)      		 - -

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition
      A55-36 (+B), A55-35 (+B2) or 2 (PCU fuse holder) - Body ground and other terminals Ignition switch off 10 kΩ or higher
    5. Reconnect the A55 inverter with converter assembly connector.
    6. Install the PCU fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  12

    Result: 

    OK 

    See step  11

  11. 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) 

  12. REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    REPLACE FUSE (PCU) 

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