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HYBRID CONTROL SYSTEM, Diagnostic DTC:P0A78-306

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DTC Code DTC Name
P0A78-306 Drive Motor "A" Inverter Performance
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DESCRIPTION

For a description of the inverter (Click here).

If the MG2 torque execution value does not correspond to the torque command value from the MG ECU to MG2, the power management control ECU will store this DTC.

Tip:

The term "drive motor A" indicates MG2.

DTC No. INF Code DTC Detection Condition Trouble Area
P0A78 306 MG2 torque execution monitoring malfunction

  • Hybrid vehicle transaxle assembly

  • Inverter with converter assembly
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WIRING DIAGRAM

Refer to the wiring diagram for DTC P0AA6-526 (Click here).

Refer to the wiring diagram for DTC P321E-318 (Click here).

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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).

    Tip:

    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 (Click here).

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PROCEDURE


  1. Click here

    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.

      Result
      Result Proceed to
      P0A78-306 only is output, or DTCs except the ones in the table below are also output. A
      Any of the following DTCs are also output. B
      DTC No. Relevant Diagnosis
      P0A1A (all INF codes)*1 Generator Control Module
      P0A1B (all INF codes)*1 Drive Motor "A" Control Module
      P0A1D (all INF codes)*1 Hybrid Powertrain Control Module
      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
      P0A4B-253 Generator Position Sensor Circuit
      P0A4C-513 Generator Position Sensor Circuit Range / Performance
      P0A4D-255 Generator 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
      P0A72 (all INF codes)*1 Generator Phase V Current
      P0A75 (all INF codes)*1 Generator Phase W Current
      P0A78-202, 266, 267, 279, 287, 503, 504, 505, 506, 586, 806, 807, 808 Drive Motor "A" Inverter Performance
      P0A7A-203, 325, 517, 518, 809, 810, 811 Generator Inverter Performance
      P0A94-547, 548, 549, 554, 555, 556, 585, 587, 589, 590 DC / DC Converter Performance
      P0AA6 (all INF codes)*1 Hybrid Battery Voltage System Isolation Fault
      P0C76-523 Hybrid Battery System Discharge Time Too Long
      P3004-132 High Voltage Power Resource
      Tip:

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

      • P0A78-306 may be stored due to a malfunction which also causes DTCs in the preceding table to be stored. In this case, first troubleshoot the output DTCs in the preceding table. Then, perform a test to attempt to reproduce the problems, and check that no DTCs are output.

    5. Turn the power switch off.


  2. Click here

    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.

      Result
      Result Proceed to
      Any of the following DTCs are also output. A
      P0A78-306 only is output, or DTCs except the ones in the table below are also output. B
      DTC No. Relevant Diagnosis
      P0A7A-344 Generator Inverter Performance
      P0A92-261, 521 Hybrid Generator Performance
      Tip:

      When the DTCs listed in the preceding table are also output, there may be a short between the HSDN (MG shut down signal) circuit and power circuit.

    5. Turn the power switch off.


  3. Click here

    CHECK POWER MANAGEMENT CONTROL ECU


    1. Turn the power switch on (IG).

    2. A0009EXE02

      Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A33-31 (HSDN) - H1-6 (E1) Power switch on (IG) Below 4.5 V
      Table 1. Text in Illustration
      *a

      Component with harness connected

      (Power Management Control ECU)

    3. Turn the power switch off.


  4. Click here

    CHECK CONNECTOR CONNECTION CONDITION (INVERTER WITH CONVERTER ASSEMBLY CONNECTOR)

    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. A00046KE03

      Check the connector connections and contact pressure of the low voltage connectors of the inverter with converter assembly (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 connectors are connected securely and there are no contact pressure problems.
      Tip:

      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.


  5. Click here

    CHECK INVERTER WITH CONVERTER ASSEMBLY (MOTOR CABLE CONNECTION CONDITION)

    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. B001VC0

      Remove the upper inverter cover (motor cable side) from the inverter with converter assembly.

    3. B001VFI

      Check that the bolts for the motor cable are tightened to the specified torque, the motor cable is connected securely, and there are no contact problems.

      Specified Condition
      T=8.0 N*m (82 kgf*cm, 71 in.*lbf)
      Note:

      Make sure that the tightening torque of the bolt is between 6.4 and 9.6 N*m (65 and 98 kgf*cm, 57 and 85 in.*lbf).

    4. Disconnect the motor cable from the inverter with converter assembly.

    5. Check for arc marks at the terminals for the motor cable.

      Result
      Result Proceed to
      The terminals are connected securely and there are no contact problems. There are no arc marks. A
      The terminals are not connected securely and there is a contact problem. There are arc marks. B
      The terminals are not connected securely and there is a contact problem. There are no arc marks. C
      The terminals are connected securely and there are no contact problems. There are arc marks. B

    6. Connect the motor cable to the inverter with converter assembly.

    7. Install the upper inverter cover (motor cable side).


    • AClick here
    • B

      REPLACE MALFUNCTIONING PARTS

    • C

      CONNECT SECURELY

  6. Click here

    CHECK HYBRID VEHICLE TRANSAXLE ASSEMBLY (MG2)

    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. B001VFH

      Remove the upper inverter cover (generator cable side) and upper inverter cover (motor cable side) from the inverter with converter assembly.

    3. B001VFDE04

      Disconnect the generator cable and motor cable from the inverter with converter assembly.

      Table 2. Text in Illustration
      *1 Generator Cable
      *2 Motor Cable
    4. B001VF9E03

      Check MG2 for an interphase short using a milliohmmeter.


      1. Using a milliohmmeter, measure the resistance according to the value(s) in the table below.

        Tip:

        If the MG2 temperature is high, the resistance will vary greatly from the specification. Therefore, measure the resistance at least 8 hours after the vehicle is stopped.

        Standard Resistance
        Tester Connection Condition Specified Condition
        d1-1 (W) - d1-3 (U) Power switch off 71.4 to 81.0 mΩ
        d1-2 (V) - d1-1 (W) Power switch off 71.4 to 81.0 mΩ
        d1-3 (U) - d1-2 (V) Power switch off 74.4 to 84.1 mΩ
        Table 3. Text in Illustration
        *1 Shield Ground
        *a

        Motor Cable

        (Inverter with Converter Assembly Side)
        Tip:

        To correct the variation of the measured resistance due to temperature, use the following formula to calculate the resistance at 20°C (68° F).


        • R20 = Rt / {1 + 0.00393 X (T - 20)}

        The calculation is based on the following:


        • R20: Resistance at 20°C (68° F) (mΩ)

        • Rt: Measured resistance (mΩ)

        • T: Temperature when the resistance is measured (°C)

    5. Using a megohmmeter set to 500 V, measure the resistance according to the value(s) in the table below.

      Note:

      Be sure to set the megohmmeter to 500 V when performing this test. Using a setting higher than 500 V can result in damage to the component being inspected.

      Standard Resistance
      Tester Connection Condition Specified Condition
      d1-1 (W) - Body ground and shield ground Power switch off 100 MΩ or higher
      d1-2 (V) - Body ground and shield ground Power switch off 100 MΩ or higher
      d1-3 (U) - Body ground and shield ground Power switch off 100 MΩ or higher

    6. Connect the generator cable and motor cable.

    7. Install the upper inverter cover (generator cable side) and upper inverter cover (motor cable side).


    • OK

      REPLACE INVERTER WITH CONVERTER ASSEMBLY (Click here)

    • NG

      REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY (Click here)

  7. Click here

    CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - INVERTER WITH CONVERTER ASSEMBLY)

    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. Disconnect the A14 inverter with converter assembly connector.

    3. Disconnect the A33 power management control ECU connector.

    4. Connect the cable to the negative (-) auxiliary battery terminal.

    5. Turn the power switch on (IG).

    6. A0006DKE03

      Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A33-31 (HSDN) or A14-40 (HSDN) - Body ground Power switch on (IG) Below 1 V
      Table 4. Text in Illustration
      *a

      Rear view of wire harness connector

      (to Power Management Control ECU)
      *b

      Front view of wire harness connector

      (to Inverter with Converter Assembly)
      Note:

      Turning the power switch on (IG) with the connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

    7. Turn the power 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
      Tester Connection Condition Specified Condition
      A33-31 (HSDN) - A33-1 (IG2) Power switch off 10 kΩ or higher
      A33-31 (HSDN) - A33-2 (IG2D) Power switch off 10 kΩ or higher
      A33-31 (HSDN) - A33-5 (+B1) Power switch off 10 kΩ or higher
      A33-31 (HSDN) - A33-6 (MREL) Power switch off 10 kΩ or higher
      A14-40 (HSDN) - A14-30 (+B) Power switch off 10 kΩ or higher
      A14-40 (HSDN) - A14-31 (+B2) Power switch off 10 kΩ or higher

    10. Reconnect the A14 inverter with converter assembly connector.

    11. Reconnect the A33 power management control ECU connector.


    • OKClick here
    • NG

      REPAIR OR REPLACE HARNESS OR CONNECTOR

  8. Click here

    CHECK INVERTER WITH CONVERTER ASSEMBLY

    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. Disconnect the A14 inverter with converter assembly connector.

    3. A000451E03

      Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A14-40 (HSDN) - A14-30 (+B) Power switch off 5 kΩ or higher
      A14-40 (HSDN) - A14-31 (+B2) Power switch off 5 kΩ or higher
      Table 5. Text in Illustration
      *a

      Component without harness connected

      (Inverter with Converter Assembly)

    4. Reconnect the A14 inverter with converter assembly connector.


    • OK

      REPLACE POWER MANAGEMENT CONTROL ECU (Click here)

    • NG

      REPLACE INVERTER WITH CONVERTER ASSEMBLY (Click here)