HYBRID CONTROL SYSTEM, Diagnostic DTC:P0A78-121

DTC Code DTC Name
P0A78-121 Drive Motor "A" Inverter Performance

DTC SUMMARY


  1. MALFUNCTION DESCRIPTION

    This DTC indicates that an overvoltage in the inverter has occurred. The cause of this malfunction may be one of the following:

    Area Main Malfunction Description Step
    Inverter low-voltage circuit The connectors are not connected properly 3
    Resolver Open or short circuit in the motor resolver or generator resolver circuit 4, 5
    Motor or generator

    • Open or short circuit in the motor or generator coils

    • An internal motor or generator malfunction (iron particles or damage from foreign objects)

    		 6, 7
    HV battery system High voltage line circuit malfunction 8
    Inverter

    • Inverter internal circuit malfunction

    • Malfunction in ECU that controls the inverter

    • Malfunction in the sensors for inverter control (current sensor, voltage sensors (VH, VL), etc.)

    		 9

DESCRIPTION

For a description of the inverter.

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If a malfunction occurs in the motor inverter, generator inverter, the MG ECU detects it and transmits this information to the hybrid vehicle control ECU assembly.

Tech Tips

The term "drive motor A" indicates the motor (MG2).

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Warning Indicate
P0A78-121 Drive Motor "A" Inverter Performance

Motor inverter overvoltage signal detected (overvoltage due to system malfunction):

Overvoltage is detected after boosting.

A malfunction is detected in any of the motor components (motor inverter, motor, MG ECU, etc.).*

(1 trip detection logic)

  • HV battery junction block assembly

  • Inverter with converter assembly

  • Service plug grip (EV battery fuse)

  • Frame wire

  • Hybrid vehicle transmission assembly

  • Generator cable

  • Motor cable

  • Hybrid vehicle control ECU assembly

  • IGCT NO. 2 fuse

  • Wire harness or connector

 Comes on

Master Warning Light:

Comes on

*: This DTC is output when a large voltage is generated by the motor inverter and there is no history information indicating the specific part.

Check related parts (inverter, motor, generator, resolver, cable, wire harness, hybrid vehicle control ECU assembly).

Related Data List
DTC No. Data List
P0A78-121 VH-Voltage after Boosting

WIRING DIAGRAM

Refer to the wiring diagram for DTC P1CAC-200.

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Refer to the wiring diagram for DTC P0AA6-526.

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Refer to the wiring diagram for DTC P324E-788.

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Refer to the wiring diagram for the inverter low-voltage circuit.

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Refer to the wiring diagram for the HV battery high-voltage line circuit.

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CAUTION / NOTICE / HINT

CAUTION:


  • Before inspecting the high-voltage system or disconnecting the low voltage connector of the inverter with converter assembly, take safety precautions such as wearing insulated gloves and removing the service plug grip to prevent electrical shocks. After removing the service plug grip, put it in your pocket to prevent other technicians from accidentally reconnecting it while you are working on the high-voltage system.

  • After removing the service plug grip, wait for at least 10 minutes before touching any of the high-voltage connectors or terminals. After waiting for 10 minutes, check the voltage at the terminals in the inspection point in the inverter with converter assembly. The voltage should be 0 V before beginning work.

    Click here

    Tech Tips

    Waiting for at least 10 minutes is required to discharge the high-voltage capacitor inside the inverter with converter assembly.

Note

After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

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Tech Tips

After the repair, clear the DTCs and perform the following procedure to check that DTCs are not output.


  1. With the engine stopped, the power switch on (READY) and the shift lever in P, depress the accelerator pedal to start the engine.

PROCEDURE


  1. CHECK DTC OUTPUT (HYBRID CONTROL)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

    4. Check for DTCs.


      Powertrain > Hybrid Control > Trouble Codes
      Result
      Result Proceed to
      P0A78-121 is stored before any of the DTCs in the table below are stored. A
      Any of the DTCs including pending DTCs in the table below are stored before P0A78-121 is stored. B
      Relevant DTC
      P0A9C-123 Hybrid Battery Temperature Sensor "A" Range / Performance
      P0A9D-123 Hybrid Battery Temperature Sensor "A" Circuit Low
      P0A9E-123 Hybrid Battery Temperature Sensor "A" Circuit High
      P0AC0-123 Hybrid Battery Pack Current Sensor Circuit Range / Performance
      P0AC1-123 Hybrid Battery Pack Current Sensor Circuit Low
      P0AC2-123 Hybrid Battery Pack Current Sensor Circuit High
      P0AC6-123 Hybrid Battery Temperature Sensor "B" Range / Performance
      P0AC7-123 Hybrid Battery Temperature Sensor "B" Circuit Low
      P0AC8-123 Hybrid Battery Temperature Sensor "B" Circuit High
      P0ACB-123 Hybrid Battery Temperature Sensor "C" Range / Performance
      P0ACC-123 Hybrid Battery Temperature Sensor "C" Circuit Low
      P0ACD-123 Hybrid Battery Temperature Sensor "C" Circuit High
      P3011-123, P3012-123, P3013-123, P3014-123, P3015-123, P3016-123, P3017-123, P3018-123, P3019-123, P3020-123, P3021-123, P3022-123, P3023-123, P3024-123, P3025-123, P3026-123 Battery Block # Becomes Weak
      P3065-123 Hybrid Battery Temperature Sensor Range/Performance Stuck "A"
      P308A-123 Hybrid Battery Voltage Sensor All Circuits Low

      Tech Tips

      P0A78-121 may be output as a result of the malfunction indicated by the DTCs above.

    5. Turn the power switch off.


    B

    GO TO DTC CHART (HYBRID BATTERY SYSTEM) Click here

    A

  2. CHECK DTC OUTPUT (HYBRID CONTROL)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

    4. Check for DTCs.


      Powertrain > Hybrid Control > Trouble Codes
      Result
      Result Proceed to
      P0A78-121 only is output, or DTCs except the ones in the table below are also output. A
      Any of the following DTCs including pending DTCs are also output. B
      Malfunction Content Relevant DTC
      Microcomputer malfunction P0A1A-151, 166, 517, 658, 791, 809 Generator Control Module
      P0A1B-198, 503, 505, 547, 554, 786, 794, 806 Drive Motor "A" Control Module
      P0A1D (all INF codes)* Hybrid Powertrain Control Module
      P1C2A-155 Generator A/D Converter Circuit
      P1C2B-192 Drive Motor "A" A/D Converter Circuit
      P1CA6-156 Generator Control Module Malfunction
      P1CA7-193 Drive Motor Control Module Malfunction
      P1CAC-200 Generator Position Sensor Angle Malfunction
      P1CAD-168 Drive Motor "A" Position Sensor Angle Malfunction
      P1CAF-792 Generator Position Sensor REF Signal Cycle Malfunction
      P1CB0-795 Drive Motor "A" Position Sensor REF Signal Cycle Malfunction
      P1CB2-793 Generator Position Sensor REF Signal Stop Malfunction
      P1CB3-796 Drive Motor "A" Position Sensor REF Signal Stop Malfunction
      P3133-659 Communication Error from Generator to Drive Motor "A"
      P3134-661 Communication Error from Drive Motor "A" to Generator
      Power source circuit malfunction P06B0-163 Sensor Power Supply "A" Circuit / Open
      P06D6-511 Sensor Reference Voltage "F" Circuit / Open
      P06E6-164 Sensor Power Supply "C" Circuit / Open
      P1C73-512 Sensor Standard Voltage "F" Circuit / Open
      Sensor and actuator circuit malfunction P0A3F-243 Drive Motor "A" Position Sensor Circuit
      P0A40-500, 504, 506, 549, 556, 808 Drive Motor "A" Position Sensor Circuit Range / Performance
      P0A41-245 Drive Motor "A" Position Sensor Circuit Low
      P0A4B-253 Generator Position Sensor Circuit
      P0A4C-513, 518, 811 Generator Position Sensor Circuit Range / Performance
      P0A4D-255 Generator Position Sensor Circuit Low
      P0A93-346 Inverter Cooling System Performance
      P0BEA-290 Drive Motor "A" Phase V Current Sensor Circuit Range / Performance
      P0BEE-298 Drive Motor "A" Phase W Current Sensor Circuit Range / Performance
      P0C73-776 Motor Electronics Coolant Pump "A" Control Performance
      P0D2E-565, 586 Drive Motor "A" Inverter Voltage Sensor Circuit Range / Performance
      P0D2F-266 Drive Motor "A" Inverter Voltage Sensor Circuit Low
      P0D30-267 Drive Motor "A" Inverter Voltage Sensor Circuit High
      P0E05-328 Generator Phase V Current Sensor Circuit Range / Performance
      P0E09-336 Generator Phase W Current Sensor Circuit Range / Performance
      P0E32-585 DC/DC Converter Voltage Sensor "A" Range / Performance
      P0E33-589 DC/DC Converter Voltage Sensor "A" Low
      P0E34-590 DC/DC Converter Voltage Sensor "A" High
      P1C3C-294 Drive Motor "A" Phase V Current Sensor Correlation
      P1C3D-302 Drive Motor "A" Phase W Current Sensor Correlation
      P1C3E-333 Generator Phase V Current Sensor Correlation
      P1C3F-341 Generator Phase W Current Sensor Correlation
      P1C4A-288 Drive Motor "A" Phase V Current Sensor Sub Circuit Range / Performance
      P1C4F-296 Drive Motor "A" Phase W Current Sensor Sub Circuit Range / Performance
      P1C54-326 Generator Phase V Current Sensor Sub Circuit Range / Performance
      P1C59-334 Generator Phase W Current Sensor Sub Circuit Range / Performance
      P1C6D-501 Drive Motor "A" Phase V Current Sensor Offset Range / Performance
      P1C6E-502 Drive Motor "A" Phase W Current Sensor Offset Range / Performance
      P1C71-515 Generator Phase V Current Sensor Offset Range / Performance
      P1C72-516 Generator Phase W Current Sensor Offset Range / Performance
      P314A-828 Inverter Coolant Pump Speed Signal
      System malfunction P0A78-113, 128, 279, 284, 286, 287, 548, 555, 807 Drive Motor "A" Inverter Performance
      P0A7A-122, 130, 322, 324, 325, 810 Generator Inverter Performance
      P0A90-509 Drive Motor "A" Performance
      P0A92-521 Hybrid Generator Performance
      P0A94-172, 553, 557 DC / DC Converter Performance
      P0ADB-227 Hybrid Battery Positive Contactor Control Circuit Low
      P0ADC-226 Hybrid Battery Positive Contactor Control Circuit High
      P0ADF-229 Hybrid Battery Negative Contactor Control Circuit Low
      P0AE0-228 Hybrid Battery Negative Contactor Control Circuit High
      P0C19-306 Drive Motor "A" Torque Delivered Performance
      P0C76-523 Hybrid Battery System Discharge Time Too Long
      P0CA3-442 DC/DC Converter Step Up Voltage Performance
      P0E71-344 Generator Torque Delivered Performance
      P1C2D-587 Hybrid Battery Voltage / DC/DC Converter Voltage Correlation
      P3004-803 High Voltage Power Resource

      Tech Tips


      • *1: If any INF codes are output for this DTC, refer to the corresponding diagnostic procedure.

      • P0A78-121 may be output as a result of the malfunction indicated by the DTCs above.


        1. The chart above is listed in inspection order of priority.

        2. Check DTCs that are output at the same time by following the listed order. (The main cause of the malfunction can be determined without performing unnecessary inspections.)

    5. Turn the power switch off.


    B

    GO TO DTC CHART (HYBRID CONTROL SYSTEM) Click here

    A

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

    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

    CAUTION:

    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 power switch on (READY), unless instructed by the repair manual because this may cause a malfunction.

    2. Check the connection condition of the low voltage connector of the inverter with converter assembly and the contact pressure of each terminal. Check the terminals for deformation, and check the connector for water ingress and foreign matter.

      Click here

      B004FMZC01
      *A for LHD *B for RHD

      Note

      Before disconnecting the connector, confirm that it is properly connected by checking that the locking claws are engaged and that the connector does not pull out.

      OK
      - The connector is connected securely.
      - The terminals are not deformed and are connected securely.
      - No water or foreign matter in the connector.
      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

      Tech Tips

      When connecting the connector, insert it with the locking lever in the raised position. Rotate the lever downward and make sure that the connector is pulled into its socket. When the locking lever is in its fully closed position, a click will be heard as its locking claws engage. After the click is heard, pull up on the connector to confirm that it is properly connected.


    B

    CONNECT SECURELY

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

  4. CHECK GENERATOR RESOLVER CIRCUIT

    Click here

    Result
    Proceed to
    NEXT

    NEXT

  5. CHECK MOTOR RESOLVER CIRCUIT

    Click here

    Result
    Proceed to
    NEXT

    NEXT

  6. CHECK GENERATOR HIGH-VOLTAGE CIRCUIT

    Click here

    Result
    Proceed to
    NEXT

    NEXT

  7. CHECK MOTOR HIGH-VOLTAGE CIRCUIT

    Click here

    Result
    Proceed to
    NEXT

    NEXT

  8. CHECK HV BATTERY HIGH-VOLTAGE LINE CIRCUIT

    Click here

    Result
    Proceed to
    NEXT

    NEXT

  9. CHECK INVERTER LOW-VOLTAGE CIRCUIT

    Click here

    Tech Tips

    If the "Inverter Low-voltage Circuit" inspection results are normal, perform the next step.

    Result
    Proceed to
    NEXT

    NEXT

    REPLACE INVERTER WITH CONVERTER ASSEMBLY Click here