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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 87 (Engine Control System (A25A-FXS) - Diagnostic Codes (P0520-P05A2)) >> SFI System >> DTC P0597-14: Thermostat Heater Control Circuit Short to Ground or Open [12/2019 - 10/2021] >> Procedure

DTC P0597-14: Thermostat Heater Control Circuit Short to Ground or Open [12/2019 - 10/2021]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. CHECK TERMINAL VOLTAGE (POWER SOURCE OF THERMOSTAT HEATER (WATER INLET WITH THERMOSTAT SUB-ASSEMBLY)) 
    GTY913161Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Thermostat Heater (Water Inlet with Thermostat Sub-assembly))
    1. Disconnect the thermostat heater (water inlet with thermostat sub-assembly) connector.
    2. Turn the ignition switch to ON.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      n6-1 (ETM+) - Body ground Ignition switch ON 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  4

    Result: 

    OK 

    See step  2

  2. INSPECT THERMOSTAT HEATER (WATER INLET WITH THERMOSTAT SUB-ASSEMBLY) 

    Refer to INSPECTION [12/2019 - 10/2021]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE THERMOSTAT HEATER (WATER INLET WITH THERMOSTAT SUB-ASSEMBLY) 

    Refer to REMOVAL [12/2019 - 10/2021]

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (THERMOSTAT HEATER (WATER INLET WITH THERMOSTAT SUB-ASSEMBLY) - ECM) 
    1. Disconnect the thermostat heater (water inlet with thermostat sub-assembly) connector.
    2. Disconnect the ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      n6-2 (ETM-) - C55-7 (HTHM) Always Below 1 Ω
      n6-2 (ETM-) or C55-7 (HTHM) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ECM 

    Refer to REMOVAL [12/2019 - 10/2022]

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  4. INSPECT EFI-MAIN NO. 2 RELAY 

    Refer to PROCEDURE - Step 2

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE EFI-MAIN NO. 2 RELAY 

    Result: 

    OK 

    See step  5

  5. CHECK TERMINAL VOLTAGE (POWER SOURCE OF EFI-MAIN NO. 2 RELAY) 
    GTY912480Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *1 No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
    *2 EFI-MAIN NO. 2 Relay
    1. Remove the EFI-MAIN NO. 2 relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      3 (EFI-MAIN NO. 2 relay) - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - EFI-MAIN NO. 2 RELAY) 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 2 RELAY - BODY GROUND) 
    1. Remove the EFI-MAIN NO. 2 relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1 (EFI-MAIN NO. 2 relay) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 2 RELAY - THERMOSTAT HEATER (WATER INLET WITH THERMOSTAT SUB-ASSEMBLY)) 
    1. Remove the EFI-MAIN NO. 2 relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    2. Disconnect the thermostat heater (water inlet with thermostat sub-assembly) connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      5 (EFI-MAIN NO. 2 relay) - n6-1 (ETM+) Always Below 1 Ω
      5 (EFI-MAIN NO. 2 relay) or n6-1 (ETM+) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (EFI-MAIN NO. 1 RELAY - EFI-MAIN NO. 2 RELAY) 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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