HYBRID CONTROL SYSTEM, Diagnostic DTC:P0A78-128

DTC Code DTC Name
P0A78-128 Drive Motor "A" Inverter Performance

DTC SUMMARY


  1. MALFUNCTION DESCRIPTION

    This DTC indicates that a large current flowed through the inverter for the drive motor. 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 2
    Resolver Open or short circuit in the drive motor resolver circuit 3
    Drive motor

    • Open or short circuit in the drive motor coils

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

    		 4
    Inverter

    • Inverter internal circuit malfunction

    • Malfunction in ECU that controls the inverter

    • Malfunction in sensor for inverter control (current sensor)

    		 5

DESCRIPTION

For a description of the inverter.

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Refer to high voltage system diagram for the System Description.

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If an abnormal amount of current flows through the drive motor inverter, the MG ECU detects it and sends a signal to inform the EV control ECU of the malfunction.

DTC No. Detection Item DTC Detection Condition Trouble Area Warning Indicate
P0A78-128 Drive Motor "A" Inverter Performance

Abnormal drive motor current value detected (system malfunction)*:

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

(1 trip detection logic)

  • FCV transaxle with motor assembly

  • Inverter with converter assembly

  • EV control ECU

  • PCU fuse

  • Wire harness or connector

Master Warning Light:

Comes on

*: This DTC is output when there is an overcurrent in the drive motor inverter and there is no history information indicating the specific part.

Check related parts (inverter, drive motor, resolver, cable, wire harness, EV control ECU).

WIRING DIAGRAM

Refer to the wiring diagram for DTC P1D8F-479.

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Refer to the wiring diagram for DTC P0AA6-485.

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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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CAUTION / NOTICE / HINT

CAUTION:


  • B006JFB
    B006JM4

    Before the following operations are conducted, take precautions to prevent electric shock by turning the power switch off, wearing insulated gloves, and removing the service plug grips from both FC stack assembly and EV battery.


    • Inspecting the high-voltage system

    • Disconnecting the low voltage connector of the inverter with converter assembly

    • Disconnecting the low voltage connector of the EV battery

    • Disconnecting the low voltage connector of the FC stack assembly

    • Disconnecting the low voltage connector of the FC converter assembly

      Tech Tips

      No removal order is specified for the service plug grips of the FC stack assembly and EV battery.

  • B006JBZ

    After removing the service plug grip from the EV battery, 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 grip from the FC stack assembly, store it in a safe location and use the "HIGH-VOLTAGE, DO NOT TOUCH" sign to notify other technicians that you are working on the high-voltage system.

  • B000ZMTC04
    *a Without waiting for 10 minutes

    After removal of the service plug grips of both FC stack assembly and EV battery, wait for at least 10 minutes before touching the high-voltage connectors and 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

    At least 10 minutes are necessary to discharge the high-voltage capacitors inside the inverter with converter assembly and FC stack 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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  • When reinstalling the service plug grip to the FC stack assembly or the EV battery, slide the lever of the service plug until the letters "UNLOCK" are completely hidden, and insert it firmly.

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  • When the vehicle is parked with the power switch off, if the FC control ECU judges that the FC stack temperature will go below 0°C (32°F), it activates the FC air compressor, hydrogen pump and FC cooling water pump for a maximum of 180 seconds and drains water from the FC stack assembly. When performing inspection or repairs with the power switch off (not on (IG) or on (READY)), disconnect the cable from the negative (-) auxiliary battery terminal before performing work (If the auxiliary battery voltage is needed to conduct inspection, warm up the FC system beforehand).

Tech Tips

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


  1. Turn the power switch on (READY) and wait for 5 seconds or more.

  2. Perform a road test according to the freeze frame data item "Vehicle Speed" for approximately 10 minutes.

PROCEDURE


  1. CHECK DTC OUTPUT (EV)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Enter the following menus: Powertrain / EV / Trouble Codes.

    4. Check for DTCs.


      Powertrain > EV > Trouble Codes
      Result
      Result Proceed to
      P0A78-128 only is output, or DTCs except the ones in the tables below are also output. A
      Any of the following DTCs including pending DTCs are also output. B
      Malfunction Content Relevant DTC
      Microcomputer malfunction P0A1B-168, 192, 193, 198, 661, 786, 794, 795, 796 Drive Motor "A" Control Module
      P0A1D (all INF codes)*1 EV Control Module
      P1D8F-474, 475, 476, 477, 481 FC Air Compressor Motor "A" Control Module
      Power source circuit malfunction P0A1B-163, 164, 511, 512 Drive Motor "A" Control Module
      Sensor and actuator circuit malfunction P0A3F-243 Drive Motor "A" Position Sensor Circuit
      P0A40-500 Drive Motor "A" Position Sensor Circuit Range / Performance
      P0A41-245 Drive Motor "A" Position Sensor Circuit Low
      P0A60 (all INF codes)*1 Drive Motor "A" Phase V Current
      P0A63 (all INF codes)*1 Drive Motor "A" Phase W Current
      System malfunction P0ADB-227 Battery Positive Contactor Control Circuit Low
      P0ADC-226 Battery Positive Contactor Control Circuit High
      P0ADF-229 Battery Negative Contactor Control Circuit Low
      P0AE0-228 Battery Negative Contactor Control Circuit High
      P3004-803 High Voltage Power Resource
      P0A78-266, 267, 279, 287, 306, 503, 504, 505, 506, 586, 806, 807, 808 Drive Motor "A" Inverter Performance
      P0A90-509 Drive Motor "A" Performance
      P1D7F-472 FC Air Compressor Motor Inverter Circuit
      P0A94-442, 547, 548, 549, 554, 555, 556, 585, 587, 589, 590 Boosting Converter Performance
      P0C76-523 EV Battery System Discharge Time Too Long

      Tech Tips


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

      • P0A78-128 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

  2. 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 to FC stack assembly and EV battery.

      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. A01MFWK

      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

      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

    B

    CONNECT SECURELY

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

  3. CHECK MOTOR RESOLVER CIRCUIT

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    Result
    Proceed to
    NEXT

    NEXT

  4. CHECK MOTOR HIGH-VOLTAGE CIRCUIT

    Click here

    Result
    Proceed to
    NEXT

    NEXT

  5. 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