RX400h · Service Manual HYBRID SYSTEM

P0A78-806

Diagnostic trouble codes

DESCRIPTION

Refer to the description of the inverter. (Click here)
If abnormal current flows through the motor inverter, the MG ECU detects the abnormal current and sends a signal to inform the HV control ECU of the malfunction.
DTC No.
 INF Code
 DTC Detection Condition
 Trouble Area
P0A78
 806
 Abnormal Motor current value detection
MG ECU malfunction
  1. Wire harness or connector
  2. HV control ECU
  3. w/ converter inverter assembly (MG ECU)
↑
 807
 Abnormal Motor current value detection
(Inverter malfunction)
  1. Wire harness or connector
  2. HV control ECU
  3. w/ converter inverter assembly (MG ECU)
↑
 808
 Abnormal Motor current value detection
(HV transaxle malfunction)
  1. Wire harness or connector
  2. HV control ECU
  3. w/ converter inverter assembly (MG ECU)

MONITOR DESCRIPTION

When the MG ECU detects an abnormal current in the motor inverter, 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:
    The DTCs shown in the table below are output:
    DTC No.
    		 Relevant Diagnosis
    P0A1D
    		 HV ECU circuit malfunction
    P0A3F, P0A40, P0A41
    		 Motor resolver circuit
    P0A60, P0A63
    		 Motor current sensor circuit
    P0A78 (other than 806, 807, and 808)
    		 Motor inverter function malfunction
    P0A90
    		 Motor function malfunction
    P0A1B
    		 MG ECU circuit

    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. P0A78-806, 807, and 808 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 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


3. CHECK W/ CONVERTER INVERTER ASSEMBLY

CAUTION:
Be sure to wear insulated gloves.

  1. A105180
    Check that the service plug grip is removed.

  1. Check that the bolts for the three-phase AC cable for Motor are tightened to the specified torque.

Torque:
10 N*m{ 102 kgf*cm , 7 ft.*lbf }



NG
TIGHTEN THEM TO SPECIFIED TORQUE
OK


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

NOTICE:
Be sure to wear insulated gloves.

  1. Disconnect the I24 connector from the MG ECU.

  1. Disconnect the M7 motor resolver connector.

  1. A105201E03
    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

  1. Turn the ignition switch off.

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

    Standard Resistance (Check for open):
    Tester Connection
    		 Specified Condition
    MRF (I24-13) - MRF (M7-1)
    		 Below 1 Ω
    MRFG (I24-23) - MRFG (M7-4)
    		 Below 1 Ω
    MSN (I24-21) - MSN (M7-2)
    		 Below 1 Ω
    MSNG (I24-20) - MSNG (M7-5)
    		 Below 1 Ω
    MCS (I24-19) - MCS (M7-3)
    		 Below 1 Ω
    MCSG (I24-18) - MCSG (M7-6)
    		 Below 1 Ω

    Standard Resistance (Check for short):
    Tester Connection
    		 Specified Condition
    MRF (I24-13) or MRF (M7-1) - Body ground
    		 10 kΩ or higher
    MRFG (I24-23) or MRFG (M7-4) - Body ground
    		 10 kΩ or higher
    MSN (I24-21) or MSN (M7-2) - Body ground
    		 10 kΩ or higher
    MSNG (I24-20) or MSNG (M7-5) - Body ground
    		 10 kΩ or higher
    MCS (I24-19) or MCS (M7-3) - Body ground
    		 10 kΩ or higher
    MCSG (I24-18) or MCSG (M7-6) - Body ground
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE HYBRID VEHICLE TRANSAXLE ASSEMBLY


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