RX400h · Service Manual HYBRID SYSTEM

P0A78-284

Diagnostic trouble codes

DESCRIPTION

Refer to the description of the inverter. (Click here)
If the motor inverter has a circuit malfunction, overheat, or internal short, the inverter transmits this information to the MFIV terminal of the MG ECU via the motor inverter fail signal line.
DTC No.
 INF Code
 DTC Detection Condition
 Trouble Area
P0A78
 284
 Motor inverter fail signal detection (overheating)
  1. Wire harness or connector
  2. Inverter cooling system
  3. Water pump w/ motor & bracket assembly
  4. Hybrid vehicle transaxle assembly (Motor)
  5. w/ converter inverter assembly (MG ECU)
  6. HV control ECU

MONITOR DESCRIPTION

If the motor inverter overheats, it transmits an inverter fail signal to the MG ECU. Upon receiving this signal, the HV control ECU illuminates the MIL and sets a DTC.

INSPECTION PROCEDURE

CAUTION:
  1. Before inspecting the high-voltage system, take safety precautions to prevent electrical shocks, such as wearing insulated gloves and removing the service plug grip. After removing the service plug grip, put it in your pocket to prevent other technicians from reconnecting it while you are working on the high-voltage system.
  2. After disconnecting the service plug grip, wait for at least 5 minutes before touching any of the high-voltage connectors or terminals.

HINT:
At least 5 minutes is required to discharge the high-voltage capacitor inside the w/ converter inverter assembly.


1. READ OUTPUT DTC (HV)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to the ON position.

  1. Select the following menu items: Powertrain / Hybrid Control / DTC.

  1. Read output DTCs. (Click here)

    Result:
    Any of the following DTCs are output:
    DTC No.
    		 Relevant Diagnosis
    P0A1D
    		 HV ECU circuit malfunction
    P0A2B, P0A2C, P0A2D
    		 Motor temperature sensor circuit
    P0A37, P0A38, P0A39
    		 Generator temperature sensor circuit
    P0A3F, P0A40, P0A41
    		 Motor resolver circuit
    P0A4B, P0A4C, P0A4D
    		 Generator resolver circuit
    P0A60, P0A63
    		 Motor current sensor circuit
    P0A72, P0A75
    		 Generator current sensor circuit
    P0A78 (Except for 284, 806, 807, and 808)
    		 Motor inverter function malfunction
    P0A7A
    		 Generator inverter function malfunction
    P0A90
    		 Motor function malfunction
    P0A92
    		 Generator function malfunction
    P0A93
    		 Inverter cooling system
    P0A94
    		 Boost converter circuit
    P0AA1, P0AA2, P0AA4, P0AA5
    		 System main relay circuit
    P3000, P3003, P0AA6, P3110
    		 High-voltage system
    P0AEE, P0AEF, P0AF0
    		 Motor inverter temperature sensor circuit
    P3221
    		 Generator inverter temperature sensor circuit
    P3226
    		 Boost converter temperature sensor circuit
    P0A05
    		 Water pump w/ Motor malfunction
    P0A79
    		 Rear Motor inverter function malfunction
    P0AF3, P0AF4, P0AF5
    		 Rear Motor temperature sensor malfunction
    P0A45, P0A46, P0A47
    		 Rear Motor resolver malfunction
    P0A69, P0A6C, P0A55
    		 Rear Motor current sensor circuit
    P0A1A, P0A1B, P0A1C
    		 MG ECU malfunction

    NOTICE:
    If P0A78-284 is output, repair the malfunctioning area indicated by the DTC, or replace the w/ converter inverter assembly after repairing the malfunctioning area.

    HINT:
    1. Turning the ignition switch to the ON position with the service plug grip and inverter cover removed causes interlock switch system DTC P0A0D-350 to be output.
    2. P0A78-284 may be output due to a malfunction which causes the DTCs in the table above to be output. In this case, first troubleshoot the output DTCs in the table above. Then, perform a reproduction test to check that no DTCs are output.



 YES
GO TO DTC CHART
NO


2. CHECK QUANTITY OF HV COOLANT

  1. Check the inverter coolant level.

    OK:
    There is sufficient amount of coolant for the inverter.



 NG
CHECK FOR COOLANT LEAKS AND ADD COOLANT
OK


3. CHECK COOLANT HOSE

  1. A114851E01
    Check that the hoses of the cooling system are not bent or clogged.

    OK:
    The hoses of the cooling system are not bent or clogged.



 NG
CORRECT TO NORMAL CONDITION
OK


4. CHECK CONNECTION CONDITION OF WATER PUMP CONNECTOR (LOOSENESS AND POOR CONTACT)

  1. A105139E01
    Check the connection of the water pump w/ motor & bracket assembly connector.

    OK:
    Connector is connected securely and there is no poor connection.



 NG
CONNECT SECURELY
OK


5. PERFORM ACTIVE TEST BY INTELLIGENT TESTER (WATER PUMP)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to the ON position.

  1. Select the following menu items: Powertrain / Hybrid Control / Active Test / Active Water Pump.

  1. During the water pump active test, check operation of the water pump.

    OK:
    There are ripples in the reservoir tank coolant.

    HINT:
    The water pump is also activated in the READY-on state.



 NG
REPLACE WATER PUMP W/ MOTOR & BRACKET ASSEMBLY CIRCUIT
OK


6. PERFORM ACTIVE TEST BY INTELLIGENT TESTER (COOLING FAN)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to the ON position.

  1. Select the following menu items: Powertrain / Engine / Active Test / Cooling Fan.

  1. Perform the cooling fan active test.

    OK:
    The electric cooling fan rotates.



 NG
CHECK COOLING FAN CIRCUIT
OK


7. CHECK CONNECTION CONDITION OF HYBRID VEHICLE CONTROL ECU CONNECTOR (LOOSENESS AND POOR CONTACT)

  1. A103658E18
    Check the connections of all HV control ECU connectors.

    OK:
    Connectors are connected securely and there is no poor connection.



 NG
CONNECT SECURELY
OK


8. CHECK CONNECTION CONDITION OF MG ECU CONNECTOR (LOOSENESS AND POOR CONTACT)

CAUTION:
Be sure to wear insulated gloves.

  1. A103665E01
    Turn the ignition switch off and remove the service plug grip. (Click here)

    NOTICE:
    Do not put the vehicle into the READY-on state with the service plug grip removed as this may cause a malfunction.

  1. Remove the inverter cover. (Click here)

    NOTICE:
    1. Wrap the interlock round terminal for the inverter cover with vinyl tape to prevent it from shorting to ground.
    2. Prevent water in the reservoir tank from entering the inverter.
    3. Removing the inverter cover causes the MG ECU board to be exposed. Therefore, temporarily install the inverter cover for each area to be inspected.

  1. Check the connections of the MG ECU connectors.

    OK:
    Connectors are connected securely and there is no poor connection.



 NG
CONNECT SECURELY
OK


9. INSPECT HYBRID VEHICLE TRANSAXLE ASSEMBLY (MOTOR)

CAUTION:
Be sure to wear insulated gloves.

  1. Check that the service plug grip is removed.

  1. A111754E02
    Disconnect the three-phase AC cable for Motor from the w/ converter inverter assembly.

  1. A111755E02
    Using a milliohmmeter, measure the resistance according to the value(s) in the table below.

    Standard Resistance:
    Tester Connection
    		 Specified Condition
    U - V
    		 48 to 59 mΩ (20°C)
    V - W
    		 48 to 59 mΩ (20°C)
    W - U
    		 48 to 59 mΩ (20°C)

    NOTICE:
    If the Motor temperature is too high, the resistance changes greatly. Therefore, measure the resistance at least 8 hours after the vehicle is stopped.

  1. To correct the resistance varying depending on the temperature, use the following formula to calculate the resistance at 20°C.

    HINT:
    1. R20 = Rt / {1 + 0.00393 X (T - 20)}
    2. R20: Resistance at 20 °C (mΩ)
    3. Rt: Measured resistance (mΩ)
    4. T: Temperature when the resistance is measured (°C)

  1. Calculate the difference between the maximum and minimum resistance.

    Standard resistance:
    Difference is 5 mΩ or less

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

    Standard Resistance:
    Tester Connection
    		 Specified Condition
    Three-phase AC Cable for Motor U terminal - Body ground and shielded wire ground
    		 10 MΩ or higher
    Three-phase AC Cable for Motor V terminal - Body ground and shielded wire ground
    		 10 MΩ or higher
    Three-phase AC Cable for Motor W terminal - Body ground and shielded wire ground
    		 10 MΩ or higher



NG
REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY
OK


10. CHECK HARNESS AND CONNECTOR (MG ECU - MOTOR RESOLVER)

CAUTION:
Be sure to wear insulated gloves.

  1. Check that the service plug grip is removed.

  1. A103666E04
    Disconnect the I24 connector from the MG ECU.

  1. Measure the voltage according to the value(s) in the table below when the ignition switch is in the ON position.

    Standard Voltage:
    Tester Connection
    		 Specified Condition
    MRF (I24-13) - Body ground
    		 Below 1 V
    MRFG (I24-23) - Body ground
    		 Below 1 V
    MSN (I24-21) - Body ground
    		 Below 1 V
    MSNG (I24-20) - Body ground
    		 Below 1V
    MCS (I24-19) - Body ground
    		 Below 1 V
    MCSG (I24-18) - Body ground
    		 Below 1 V

    NOTICE:
    Turning the ignition switch to the ON position with the MG ECU connectors disconnected causes other DTCs to be stored. Clear the DTCs after performing the inspection.

  1. Turn the ignition switch off.

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

    Standard Resistance:
    Tester Connection
    		 Specified Condition
    MRF (I24-13) - MRFG (I24-23)
    		 7.65 to 10.2 Ω
    MSN (I24-21) - MSNG (I24-20)
    		 12.6 to 16.8 Ω
    MCS (I24-19) - MCSG (I24-18)
    		 12.6 to 16.8 Ω

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

    Standard Resistance:
    Tester Connection
    		 Specified Condition
    MRF (I24-13) or MRFG (I24-23) - Body ground
    		 10 MΩ or higher
    MSN (I24-21) or MSNG (I24-20) - Body ground
    		 10 MΩ or higher
    MCS (I24-19) or MCSG (I24-18) - Body ground
    		 10 MΩ or higher



OK
REPLACE W/ CONVERTER INVERTER ASSEMBLY
NG


11. CHECK CONNECTION CONDITION OF MOTOR RESOLVER CONNECTOR (LOOSENESS AND POOR CONTACT)

  1. A105165
    Check the connection of the motor resolver connector.

OK:
Connector is connected securely and there is no poor connection.



 NG
CONNECT SECURELY
OK


12. INSPECT MOTOR RESOLVER

  1. A083675E04
    Disconnect the M7 motor resolver connector.

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

    Standard Resistance:
    Tester Connection
    		 Specified Condition
    MRF (M7-1) - MRFG (M7-4)
    		 7.65 to 10.2 Ω
    MSN (M7-2) - MSNG (M7-5)
    		 12.6 to 16.8 Ω
    MCS (M7-3) - MCSG (M7-6)
    		 12.6 to 16.8 Ω

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

    Standard Resistance:
    Tester Connection
    		 Specified Condition
    MRF (M7-1) - MSN (M7-2)
    		 10 MΩ or higher
    MRF (M7-1) - MCS (M7-3)
    		 10 MΩ or higher
    MSN (M7-2) - MCS (M7-3)
    		 10 MΩ or higher
    MRFG (M7-4) - MSNG (M7-5)
    		 10 MΩ or higher
    MRFG (M7-4) - MCSG (M7-6)
    		 10 MΩ or higher
    MSNG (M7-5) - MCSG (M7-6)
    		 10 MΩ or higher
    Each terminal listed above - transaxle housing
    		 10 MΩ or higher



NG
REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY
OK

REPAIR OR REPLACE HARNESS OR CONNECTOR


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