HYBRID CONTROL SYSTEM, Diagnostic DTC:P0A78-202

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

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

INSPECTION PROCEDURE

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 disconnecting 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.

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.

  • 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.

Tech Tips

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

PROCEDURE


  1. CHECK HYBRID VEHICLE TRANSAXLE 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. A01NE6E

      Remove the inverter terminal cover from the inverter with converter assembly.

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

    4. A01NEK6E04
      Text in Illustration
      *1 Motor Cable
      *2 Shield Ground

      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.

        Tech Tips

        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 Switch Condition Specified Condition
        z38-3 (U) - z38-2 (V) Power switch off 52 to 60 mΩ
        z38-2 (V) - z38-1 (W) Power switch off 50 to 58 mΩ
        z38-1 (W) - z38-3 (U) Power switch off 50 to 58 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)

    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 Switch Condition Specified Condition
      z38-3 (U) - Body ground and shield ground Power switch off 100 MΩ or higher
      z38-2 (V) - Body ground and shield ground Power switch off 100 MΩ or higher
      z38-1 (W) - Body ground and shield ground Power switch off 100 MΩ or higher

    6. Connect the generator cable and motor cable.

    7. Install the inverter terminal cover.


    NG

    REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY Click here

    OK

  2. REPLACE INVERTER WITH CONVERTER ASSEMBLY


    1. Replace the inverter with converter assembly Click here.


    NEXT

    CHECK DTC OUTPUT (HV) Click here

  3. REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY


    1. Replace the hybrid vehicle transaxle assembly Click here.


    NEXT

  4. REPLACE INVERTER WITH CONVERTER ASSEMBLY


    1. Replace the inverter with converter assembly Click here.


    NEXT

  5. CHECK DTC OUTPUT (HV)


    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 P3246-202, be sure to troubleshoot all the other DTCs.


    NEXT

    GO TO DTC CHART Click here