HYBRID CONTROL SYSTEM, Diagnostic DTC:P0A78-202

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

DTC SUMMARY


  1. MALFUNCTION DESCRIPTION


      Internal inverter malfunction

    • Inverter with converter assembly internal circuit malfunction


      Hybrid vehicle transmission assembly malfunction

    • Open or short circuit

    • Iron particles or damage from foreign objects

DESCRIPTION

For a description of the inverter.

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Tech Tips

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

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Warning Indicate
P0A78-202 Drive Motor "A" Inverter Performance

Malfunction (short circuit) in the motor inverter inside the inverter with converter assembly:

Current flowing to any of the phases exceeds a certain level after a DTC (indicating a motor inverter malfunction: overheating, overcurrent or circuit malfunction) is stored and the motor inverter is shutdown.

(1 trip detection logic)

  • Inverter with converter assembly

  • Hybrid vehicle transmission assembly

  • Motor cable

 Comes on

Master Warning Light:

Comes on

WIRING DIAGRAM

Refer to the wiring diagram for DTC P0AA6-526.

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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.

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    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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  • DTC P0A78-202 is stored after DTCs P0A1B-505, P0A40-506, P0A78-113, 284, 286 and/or 287 are stored. After troubleshooting and repairing the malfunction which caused DTC P0A78-202 to be stored, 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 transmission 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 transmission 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 transmission assembly.

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.

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

PROCEDURE


  1. CHECK HYBRID VEHICLE TRANSMISSION 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. Disconnect the motor cable from the hybrid vehicle transmission assembly.

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    3. B004FEOC08
      *a

      Component without motor cable connected

      (Hybrid Vehicle Transmission Assembly)

      Check motor (MG2) for an interphase short using a milliohmmeter.


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

        Tech Tips

        If the motor (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
        q2-1 (W) - q2-2 (V) Power switch off 44.9 to 49.7 mΩ
        q2-2 (V) - q2-3 (U) Power switch off 45.2 to 50.0 mΩ
        q2-3 (U) - q2-1 (W) Power switch off 45.0 to 49.8 mΩ

        Tech Tips

        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)

    4. 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
      q2-1 (W) - Body ground Power switch off 100 MΩ or higher
      q2-2 (V) - Body ground Power switch off 100 MΩ or higher
      q2-3 (U) - Body ground Power switch off 100 MΩ or higher

    5. Connect the motor cable.

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE MOTOR CABLE Click here

    OK

  2. REPLACE MOTOR CABLE

    Click here

    Result
    Proceed to
    NEXT

    NEXT

  3. REPLACE INVERTER WITH CONVERTER ASSEMBLY

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    Result
    Proceed to
    NEXT

    NEXT

    GO TO STEP 7 Click here

  4. REPLACE MOTOR CABLE

    Click here

    Result
    Proceed to
    NEXT

    NEXT

  5. REPLACE HYBRID VEHICLE TRANSMISSION ASSEMBLY

    Click here

    Result
    Proceed to
    NEXT

    NEXT

  6. REPLACE INVERTER WITH CONVERTER ASSEMBLY

    Click here

    Result
    Proceed to
    NEXT

    NEXT

  7. CHECK DTC OUTPUT (HYBRID CONTROL)


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


      Powertrain > Hybrid Control > Trouble Codes
      Result
      Relevant DTC
      P0A1B-505 Drive Motor "A" Control Module
      P0A40-506 Drive Motor "A" Position Sensor Circuit Range / Performance
      P0A78-113, 284, 286, 287 Drive Motor "A" Inverter Performance

      Note

      DTC P0A78-202 is stored after DTCs P0A1B-505, P0A40-506, P0A78-113, 284, 286 and/or 287 are stored. After troubleshooting and repairing the malfunction which caused DTC P0A78-202 to be stored, be sure to troubleshoot all the other DTCs.

      Result
      Proceed to
      NEXT

    NEXT

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