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HYBRID CONTROL SYSTEM, Diagnostic DTC:P0A78-202

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DTC Code DTC Name
P0A78-202 Drive Motor "A" Inverter Performance
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DESCRIPTION

For a description of the inverter (Click here).

DTC No. INF Code DTC Detection Condition Trouble Area
P0A78 202 Malfunction (short circuit) in the motor inverter inside the inverter with converter assembly

  • Inverter with converter assembly

  • Hybrid vehicle transaxle assembly
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WIRING DIAGRAM

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

  • DTC P0A78-202 is stored after any of DTCs P0A78-113, 128, 284, 286, 287, 505, 506, 806, 807 and 808 are stored. After troubleshooting and repairing DTC P0A78-202, be sure to troubleshoot all the other DTCs.

  • Depending on the conditions in which the vehicle is being operated when a short circuit occurs in the inverter with converter assembly, the hybrid vehicle transaxle assembly may be affected. As this DTC is stored if a short circuit occurs in the inverter with converter assembly, it is necessary to perform a road test to check the hybrid vehicle transaxle assembly. If problems are found, replace the malfunctioning parts.

  • After completing the repair, including the repair of previously output DTCs, drive the vehicle at a speed of approximately 40 km/h (25 mph) for 1 minute and check that DTC P0A90-251 (Drive Motor "A" Performance) is not output. If DTC P0A90-251 (Drive Motor "A" Performance) is output, replace the hybrid vehicle transaxle assembly.

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PROCEDURE


  1. 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 1. 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 2. 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).


  2. Click here

    REPLACE INVERTER WITH CONVERTER ASSEMBLY

    (Click here)


  3. Click here

    CHECK DTC OUTPUT (HYBRID CONTROL)


    1. Check the other DTCs that were output together with DTC P0A78-202.

      Result
      DTC No. Relevant Diagnosis
      P0A78-113, 128, 284, 286, 287, 505, 506, 806, 807, 808 Drive Motor "A" Inverter Performance
      Note:

      DTC P0A78-202 is stored after any of DTCs P0A78-113, 128, 284, 286, 287, 505, 506, 806, 807 and 808 are stored. After troubleshooting and repairing DTC P0A78-202, be sure to troubleshoot all the other DTCs.


    • NEXT

      GO TO DTC CHART (HYBRID CONTROL SYSTEM) (Click here)

  4. Click here

    REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY

    (Click here)


  5. Click here

    REPLACE INVERTER WITH CONVERTER ASSEMBLY

    (Click here)


  6. Click here

    CHECK DTC OUTPUT (HYBRID CONTROL)


    1. Check the other DTCs that were output together with DTC P0A78-202.

      Result
      DTC No. Relevant Diagnosis
      P0A78-113, 128, 284, 286, 287, 505, 506, 806, 807, 808 Drive Motor "A" Inverter Performance
      Note:

      DTC P0A78-202 is stored after any of DTCs P0A78-113, 128, 284, 286, 287, 505, 506, 806, 807 and 808 are stored. After troubleshooting and repairing DTC P0A78-202, be sure to troubleshoot all the other DTCs.


    • NEXT

      GO TO DTC CHART (HYBRID CONTROL SYSTEM) (Click here)