HYBRID CONTROL SYSTEM, Diagnostic DTC:P0A01-726, P0A04-725

DTC Code DTC Name
P0A01-726 Motor Electronics Coolant Temperature Sensor Circuit Range / Performance
P0A04-725 Motor Electronics Coolant Temperature Sensor Circuit Intermittent

DESCRIPTION

The hybrid vehicle control ECU assembly detects HV coolant temperature using the coolant temperature sensor built into the inverter with converter assembly. The hybrid vehicle control ECU assembly uses signals from the coolant temperature sensor to check the effectiveness of the inverter cooling system. If necessary, the hybrid vehicle control ECU assembly will limit inverter output to help prevent inverter overheating. The hybrid vehicle control ECU assembly also detects malfunctions in the sensor based on the HV coolant temperature sensor values. The inverter with converter assembly detects malfunctions in the HV coolant temperature sensor and its wiring.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Warning Indicate
P0A01-726 Motor Electronics Coolant Temperature Sensor Circuit Range / Performance

Abnormal deviation in inverter coolant temperature sensor output.

The difference between the estimated inverter coolant temperature and the sensor detected temperature exceeds a certain amount for 10 seconds.

(1 trip detection logic)

  • Inverter cooling system

  • Cooling fan system

  • Inverter with converter assembly

  • Wire harness or connector

 Comes on

Master Warning Light:

Comes on
P0A04-725 Motor Electronics Coolant Temperature Sensor Circuit Intermittent

Sudden change in HV coolant temperature sensor output or hunting:

Unusual sudden change in HV coolant temperature sensor output occurs and the offset continues for a certain period of time.

Unusual sudden change in HV coolant temperature sensor output occurs repeatedly.

(1 trip detection logic)

  • Inverter cooling system

  • Cooling fan system

  • Inverter with converter assembly

  • Wire harness or connector

 Comes on

Master Warning Light:

Comes on
Related Data List
DTC No. ECU Data List
P0A01-726

  • Inverter Coolant Water Temperature

  • Ambient Temperature

  • W/P Run Control Duty

  • Inverter W/P Revolution
P0A04-725

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

    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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Tech Tips

After the repair, clear the DTCs and perform the following procedure to check that DTCs are not output.


  1. Turn the power switch on (READY) and wait for 90 seconds or more.

  2. Drive the vehicle for approximately 10 minutes referring to the following freeze frame data or Data List items: "Vehicle Spd".

PROCEDURE


  1. CHECK DTC OUTPUT (HYBRID CONTROL)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

    4. Check for DTCs.


      Powertrain > Hybrid Control > Trouble Codes
      Result
      Result Proceed to
      P0A01-726 or P0A04-725 only is output, or DTCs except the ones in the table below are also output. A
      Any of the following DTCs are also output. B
      Relevant DTC
      P0A93-346 Inverter Cooling System Performance
      P0C73-776 Motor Electronics Coolant Pump "A" Control Performance
      P314A-828 Inverter Coolant Pump Speed Signal

      Tech Tips

      P0A01-726 or P0A04-725 may be stored due to a malfunction which also causes DTCs in the preceding table to be stored. In this case, first troubleshoot the output DTCs in the preceding table. Then, perform a test to attempt to reproduce the problems, and check that no DTCs are output.

    5. Turn the power switch off.


    B

    GO TO DTC CHART (HYBRID CONTROL SYSTEM) Click here

    A

  2. CHECK CONNECTOR CONNECTION CONDITION (INVERTER WITH CONVERTER ASSEMBLY CONNECTOR)

    Result
    Result Proceed to
    OK A
    NG (The connector is not connected securely.) B
    NG (The terminals are not making secure contact or are deformed, or water or foreign matter exists in the connector.) C

    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. Check the connection condition of the low voltage connector of the inverter with converter assembly and the contact pressure of each terminal. Check the terminals for deformation, and check the connector for water ingress and foreign matter.

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      A0020YPC01
      *A for LHD *B for RHD

      Note

      Before disconnecting the connector, confirm that it is properly connected by checking that the locking claws are engaged and that the connector does not pull out.

      OK
      - The connector is connected securely.
      - The terminals are not deformed and are connected securely.
      - No water or foreign matter in the connector.
      Result
      Result Proceed to
      OK A
      NG (The connector is not connected securely.) B
      NG (The terminals are not making secure contact or are deformed, or water or foreign matter exists in the connector.) C

      Tech Tips

      When connecting the connector, insert it with the locking lever in the raised position. Rotate the lever downward and make sure that the connector is pulled into its socket. When the locking lever is in its fully closed position, a click will be heard as its locking claws engage. After the click is heard, pull up on the connector to confirm that it is properly connected.


    B

    CONNECT SECURELY

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

  3. CHECK QUANTITY OF HV COOLANT


    1. Check the HV coolant level in the inverter reserve tank.

    2. Check for HV coolant leaks.

      Result
      Result Proceed to
      No leaks are found and coolant level in the inverter reserve tank assembly is above the low line. A
      No leaks are found and coolant level in the inverter reserve tank assembly is below the low line. B
      HV coolant leaks are evident. C

      Tech Tips

      After repairing the HV coolant leaks and adding coolant, perform the "Activate the (Inverter) Water Pump" Active Test (HV Active Test item) and the "Control the Electric Cooling Fan" Active Test (Engine Active Test item) and make sure that there are no malfunctions.


    B

    ADD HV COOLANT

    C

    INSPECT FOR COOLANT LEAK AND ADD COOLANT

    A

  4. CHECK COOLANT HOSE


    1. Check that the cooling system hoses are not kinked or clogged.

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE COOLANT HOSE

    OK

  5. PERFORM ACTIVE TEST USING GTS (CONTROL THE ELECTRIC COOLING FAN)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Electric Cooling Fan.

    4. Perform the "Control the Electric Cooling Fan" Active Test.


      Powertrain > Engine and ECT > Active Test
      Tester Display
      Control the Electric Cooling Fan
      OK
      The cooling fan rotates.

    5. Turn the power switch off.

      Result
      Proceed to
      OK
      NG

    NG

    CHECK COOLING FAN SYSTEM Click here

    OK

  6. CHECK HV COOLANT (CHECK FOR CONDITIONS THAT MAY HAVE CAUSED FREEZING)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

    4. Read the freeze frame data item Ambient Temperature using the GTS.


      Powertrain > Hybrid Control > Trouble Codes

    5. Check if the freeze frame data item Ambient Temperature is below the freezing temperature of the HV coolant.

      Result
      Result Proceed to
      Ambient Temperature value is below freezing temperature of the HV coolant. A
      Ambient Temperature value is above freezing temperature of the HV coolant. B

      Tech Tips


      • HV coolant (SLLC) with a 30% concentration freezes at -15 °C (5°F) and HV coolant (SLLC) with a 50% concentration freezes at -35°C (-31°F).

      • If the HV coolant freezes in the HV radiator or HV water pump, the coolant temperature in the inverter with converter assembly rises because the HV coolant cannot circulate. As a result, a DTC may be stored.

      • A DTC is stored when the water pump impeller cannot rotate due to freezing of the HV coolant.

      • If DTCs are output due to freezing of the LLC, the problem symptom cannot be reproduced. Check the LLC replacement history and whether the LLC was frozen based on the ambient temperature when the DTCs were stored.

    6. Turn the power switch off.


    B

    REPLACE INVERTER WITH CONVERTER ASSEMBLY Click here

    A

  7. REPLACE HV COOLANT


    1. Replace the HV coolant with coolant having an appropriate concentration (appropriate freeze point) for the vehicle usage conditions.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    COMPLETED