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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 61 (Hybrid Control System (2WD) - Diagnostic Codes (7 Of 7) & Circuit Tests) >> HYBRID CONTROL SYSTEM (for 2WD) >> Cooling System [10/2021 - 11/2023] >> Procedure

Cooling System [10/2021 - 11/2023]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. CHECK VEHICLE CONDITION 
    1. Make sure that the front side of the radiator grille is not blocked with anything.
    2. Ask the customer if the front side of the radiator grille was blocked with anything.

      Result

      Result Proceed to
      Not blocked. A
      Is/was blocked. B

      HINT: 

      If the radiator grille is blocked, the inverter coolant temperature will increase and this DTC may be stored.

    Result: 

    B 

    IF EQUIPPED, EXPLAIN TO CUSTOMER THAT OPTIONAL COMPONENTS WILL BE REMOVED 

    Result: 

    A 

    See step  2

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

      HINT: 

      • After repairing the HV coolant leaks and adding coolant, perform the Active Tests "Activate the Inverter Water Pump" (Hybrid Control System) and "Control the Cooling Fan Duty Ratio" (Engine Control System) and make sure that there are no malfunctions.
      • If there are signs of coolant leakage around the connecting parts of a hose and the inverter with converter assembly, replace the hose with a new one.

    Result: 

    B 

    ADD HV COOLANT 

    Result: 

    C 

    INSPECT FOR COOLANT LEAK AND ADD COOLANT 

    Result: 

    A 

    See step  3

  3. CHECK COOLANT HOSE 
    1. Check that the cooling system hoses are not kinked or clogged.

      OK

      The cooling system hoses are not kinked or clogged.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE COOLANT HOSE 

    Result: 

    OK 

    See step  4

  4. PERFORM ACTIVE TEST USING GTS (CONTROL THE ENGINE COOLING FAN DUTY RATIO) 
    1. Perform the "Control the Engine Cooling Fan Duty Ratio" Active Test.

      Powertrain > Engine > Active Test 

      Tester Display
      Control the Engine Cooling Fan Duty Ratio

      OK

      GTS Operation Fan Operation
      30 - 100% Cooling fan operates
      0% Cooling fan stops

      Result

      Result Proceed to
      Cooling fan operate A
      Cooling fan does not operate B
      Cooling fan do not stop
    2. Turn the ignition switch off.

    Result: 

    B 

    CHECK COOLING FAN SYSTEM 

    Refer to Cooling Fan Circuit [12/2019 - 11/2023]

    Result: 

    A 

    See step  5

  5. CHECK GRILLE SHUTTER SYSTEM 
    1. Check the Grill Shutter System.

      Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2021 - ]

      OK

      The Grill Shutter System is normal.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    CHECK GRILLE SHUTTER SYSTEM 

    Refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2021 - ]

    Result: 

    OK 

    See step  6

  6. PERFORM ACTIVE TEST USING GTS (ACTIVATE THE INVERTER WATER PUMP) 
    NOTE:
    • Make sure that the HV coolant level is above the low line of the inverter reserve tank.
    • Be sure to perform the inspection with the auxiliary battery voltage at 12 V or more.

    HINT: 

    When the auxiliary battery voltage is low, the inverter water pump assembly may not operate.

    1. According to the display on the GTS, perform the Active Test "Activate the Inverter Water Pump" and check the value of the Data List item "Inverter Water Pump Revolution".

      Powertrain > Hybrid Control > Active Test 

      Active Test Display
      Activate the Inverter Water Pump
      Data List Display
      Inverter Water Pump Revolution

      OK

      Tester Display Condition Specified Condition
      Inverter Water Pump Revolution Ignition switch ON
      During Active Test      		 3176 to 8617 rpm

      HINT: 

      • Perform the Active Test with the inverter coolant temperature between -15 and 65°C (5 to 149°F).
      • When the inverter water pump assembly is not operating, the Data List item "Inverter Water Pump Revolution" displays a value 200 rpm or less.
    2. Turn the ignition switch off.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  9

    Result: 

    OK 

    See step  7

  7. READ VALUE USING GTS (DATA LIST) 
    1. Turn the ignition switch to ON (READY) and wait for 1 minute with the engine stopped.
    2. Read the Data List with the engine stopped.

      Powertrain > Hybrid Control > Data List 

      Tester Display
      Generator Inverter Calculated Temperature
      Motor Inverter Temperature
      Rear Motor Inverter Temperature
      Boosting Converter Temperature (Upper)
      Boosting Converter Temperature (Lower)
      Inverter Coolant Water Temperature

      Result

      Result Proceed to
      Other than below. A
      "Inverter Coolant Water Temperature" value is higher than the displayed temperature of any other Data List item by 20°C (68°F) or more. B

      HINT: 

      The lower limit temperature that can be displayed for "Generator Inverter Calculated Temperature", "Motor Inverter Temperature", "Boosting Converter Temperature (Upper)" and "Boosting Converter Temperature (Lower)" is 0°C (32°F). The lower limit temperature for "Inverter Coolant Water Temperature" is -40°C (-40°F). The "Inverter Coolant Water Temperature" value displayed on the GTS may be lower than the others, but this is not a malfunction.

    3. Turn the ignition switch off.

    Result: 

    B 

    REPLACE INVERTER WITH CONVERTER ASSEMBLY 

    Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    Result: 

    A 

    See step  8

  8. CHECK HV COOLANT (CHECK FOR CONDITIONS THAT MAY HAVE CAUSED FREEZING) 
    1. Read the Freeze Frame Data item "Ambient Temperature" using the GTS.

      Powertrain > Hybrid Control > Trouble Codes 

    2. 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 above freezing temperature of the HV coolant. A
      Ambient Temperature value is below freezing temperature of the HV coolant. B

      HINT: 

      • 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 inverter 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 inverter 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.
    3. Turn the ignition switch off.

    Result: 

    A 

    COOLING SYSTEM NORMAL (PERFORM NEXT STEP FOR REFERENCED DTC) 

    Result: 

    B 

    REPLACE HV COOLANT 

    Refer to REPLACEMENT [12/2019 - ]

  9. CHECK CONNECTOR CONNECTION CONDITION (HYBRID VEHICLE CONTROL ECU CONNECTOR) 

    Refer to PROCEDURE - Step 1

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    CONNECT SECURELY 

    Result: 

    OK 

    See step  10

  10. CHECK CONNECTOR CONNECTION CONDITION (INVERTER WATER PUMP ASSEMBLY CONNECTOR) 
    1. Check the connector connections and contact pressure of the relevant terminals for the A56 inverter water pump assembly connector.

      Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE [12/2019 - ]

      GTY931844Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      OK

      The connector is connected securely, the terminals are not deformed or corroded and there are no contact problems.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    CONNECT SECURELY 

    Result: 

    OK 

    See step  11

  11. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - INVERTER WATER PUMP ASSEMBLY) 
    1. Disconnect the A31 hybrid vehicle control ECU connector.
    2. Disconnect the A56 inverter water pump assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      A31-34 (IWP) - A56-3 (SWP) Ignition switch off Below 1 Ω

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition
      A31-34 (IWP) or A56-3 (SWP) - Body ground and other terminals Ignition switch off 10 kΩ or higher
      GTY930052Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Hybrid Vehicle Control ECU)
      *b Front view of wire harness connector
      (to Inverter Water Pump Assembly)

      HINT: 

      Check the condition (looseness, deterioration, etc.) of the wire to body ground for the inverter water pump assembly.

    4. Reconnect the A56 inverter water pump assembly connector.
    5. Reconnect the A31 hybrid vehicle control ECU connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  12

  12. READ VALUE USING GTS (INVERTER WATER PUMP REVOLUTION) 
    NOTE:

    Be sure to perform the inspection with the auxiliary battery voltage at 12 V or more.

    HINT: 

    When the auxiliary battery voltage is low, the inverter water pump assembly may not operate.

    1. Remove the INV W/PMP fuse from No. 1 engine room relay block and No. 1 junction block assembly.
      GTY848344Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
      *2 INV W/PMP Fuse
    2. According to the display on the GTS, read the Data List.

      Powertrain > Hybrid Control > Data List 

      Tester Display
      Inverter Water Pump Revolution

      OK

      Tester Display Condition Specified Condition
      Inverter Water Pump Revolution Ignition switch ON 200 rpm or less
    3. Turn the ignition switch off.
    4. Install the INV W/PMP fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HYBRID VEHICLE CONTROL ECU 

    Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    Result: 

    OK 

    See step  13

  13. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - INVERTER WATER PUMP ASSEMBLY) 
    1. Disconnect the A31 hybrid vehicle control ECU connector.
    2. Remove the INV W/PMP relay from No. 1 engine room relay block and No. 1 junction block assembly.
      GTY912988Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
      *2 INV W/PMP Relay Holder
    3. Connect terminals 3 and 5 of the INV W/PMP relay holder.

      HINT: 

      Make a short circuit between terminals 3 and 5 to supply +B voltage to the inverter water pump.

    4. Measure the voltage according to the value(s) in the table below.
      GTY860826Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU)      		 *b Front view of wire harness connector
      (to Hybrid Vehicle Control ECU)

      Standard Voltage

      Tester Connection Condition Specified Condition
      A31-34 (IWP) - H67-3 (E1) INV W/PMP relay holder terminals 3 and 5 connected
      Ignition switch off      		 11 to 14 V
      NOTE:

      Make sure to check for and clear DTCs after performing this inspection.

    5. Install the INV W/PMP relay.
    6. Reconnect the A31 hybrid vehicle control ECU connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  15

    Result: 

    OK 

    See step  14

  14. CHECK HYBRID VEHICLE CONTROL ECU (CHECK WAVEFORM) 
    1. Connect an oscilloscope between the hybrid vehicle control ECU terminals specified in the table below.
    2. Turn the ignition switch to ON.
    3. Check the waveform while turning the ignition switch to ON.
      GTY894650Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Hybrid Vehicle Control ECU)      		 - -
      Item Content
      Terminal A31-34 (IWP) - H67-3 (E1)
      Equipment Setting 5 V/DIV., 50 ms./DIV.
      Condition Ignition switch ON

      OK

      Waveform duty ratio is between 3% and 9%.

    4. Turn the ignition switch off.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HYBRID VEHICLE CONTROL ECU 

    Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    Result: 

    OK 

    See step  15

  15. REPLACE INVERTER WATER PUMP ASSEMBLY 

    Refer to REMOVAL [12/2019 - ]

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    See step  16

  16. ADD HV COOLANT AND PERFORM AIR BLEEDING 
    1. After replacing the inverter water pump assembly, add HV coolant and perform air bleeding.

      Refer to REPLACEMENT [12/2019 - ]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    END 

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