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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 107 (Hybrid Control System (2WD) - Diagnostic Codes (4 Of 7)) >> HYBRID CONTROL SYSTEM (for 2WD) >> DTC P0C73-96: Motor Electronics Coolant Pump "A" Component Internal Failure [12/2019 - 11/2023] >> Procedure

DTC P0C73-96: Motor Electronics Coolant Pump "A" Component Internal Failure [12/2019 - 11/2023]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. CHECK DTC OUTPUT (HYBRID CONTROL) 
    1. Check for DTCs.

      Powertrain > Hybrid Control > Trouble Codes 

      Result

      Result Proceed to
      P0C73-96 only is output, or DTCs except the ones in the table below are also output. A
      Any of the following DTCs including pending DTCs are also output. B
      Malfunction Content Relevant DTC
      Microcomputer malfunction P0606-47 Hybrid/EV Powertrain Control Module Processor Watchdog / Safety MCU Failure
      P0688-1F ECM/PCM Power Relay Sense Circuit Intermittent
      Sensor and actuator circuit malfunction P314A-31 Motor Electronics Coolant Pump "A" No Signal

      HINT: 

      P0C73-96 may be output as a result of the malfunction indicated by the DTCs above.

      1. The chart above is listed in inspection order of priority.
      2. Check DTCs that are output at the same time by following the listed order. (The main cause of the malfunction can be determined without performing unnecessary inspections.)
    2. Turn the ignition switch off.

    Result: 

    B 

    GO TO DTC CHART (HYBRID CONTROL SYSTEM). Refer to  DIAGNOSTIC TROUBLE CODE CHART [12/2019 - 09/2020]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [09/2020 - 10/2021]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [10/2021 - 11/2023] 

    Result: 

    A 

    See step  2

  2. 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.
    • When the inverter water pump assembly signal line (SWP - IWP) is open or its connection is faulty, the inverter water pump assembly is operated forcibly.
    1. 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

      HINT: 

      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  6

    Result: 

    OK 

    See step  3

  3. CLEAR DTC 
    1. Read and record the DTCs and Freeze Frame Data.

      Powertrain > Hybrid Control > Trouble Codes 

    2. Clear the DTCs and Freeze Frame Data.

      Powertrain > Hybrid Control > Clear DTCs 

    3. Turn the ignition switch off and wait for 2 minutes or more.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  4

  4. 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  6

    Result: 

    OK 

    See step  5

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

    Refer to PROCEDURE - Step 8 [12/2019 - 10/2021] , or refer to PROCEDURE - Step 8 [10/2021 - 11/2023]

    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

    Result: 

    A 

    See step  12

    Result: 

    B 

    REPLACE HV COOLANT. Refer to  REPLACEMENT [12/2019 - ] 

  6. 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  7

  7. CHECK CONNECTOR CONNECTION CONDITION (INVERTER WATER PUMP ASSEMBLY CONNECTOR) 

    Refer to PROCEDURE - Step 10 [12/2019 - 10/2021] , or refer to PROCEDURE - Step 10 [10/2021 - 11/2023]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    CONNECT SECURELY 

    Result: 

    OK 

    See step  8

  8. 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  9

  9. 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  10

  10. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - INVERTER WATER PUMP ASSEMBLY) 
    1. 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
    2. Disconnect the A31 hybrid vehicle control ECU connector.
    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. Reconnect the A31 hybrid vehicle control ECU connector.
    6. Install the INV W/PMP relay.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  12

    Result: 

    OK 

    See step  11

  11. 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.
      GTY894653Courtesy 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  12

  12. REPLACE INVERTER WATER PUMP ASSEMBLY 

    Refer to REMOVAL [12/2019 - ]

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    See step  13

  13. 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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