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ECD SYSTEM, Diagnostic DTC:P0115

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DTC Code DTC Name
P0115 Engine Coolant Temperature Circuit
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DESCRIPTION

The engine coolant temperature sensor senses the coolant temperature. A thermistor built into the sensor changes the resistance value according to the coolant temperature. The lower the coolant temperature, the greater the thermistor resistance value, and the higher the coolant temperature, the lower the thermistor resistance value.

The engine coolant temperature sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the engine coolant temperature sensor from the terminal THW via a resistor R. That is, the resistor R and the engine coolant temperature sensor are connected in series. When the resistance value of the engine coolant temperature sensor changes in accordance with changes in the coolant temperature, the potential at the terminal THW also changes. Based on this signal, the ECM increases the fuel injection volume to improve driveability during cold engine operation.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0115 Engine Coolant Temperature Circuit Open or short in engine coolant temperature sensor circuit for 0.5 seconds or more.

  • Open or short in engine coolant temperature sensor circuit

  • Engine coolant temperature sensor

  • ECM

 Comes on DTC stored
Table 1. *a Engine Coolant Temperature Sensor
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WIRING DIAGRAM

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CAUTION / NOTICE / HINT

Tip:

Read freeze frame data using the GTS. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, and other data from the time the malfunction occurred.

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PROCEDURE


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    READ VALUE USING GTS (ENGINE COOLANT TEMPERATURE)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON and turn the GTS on.

    3. Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.


      1. Powertrain > Engine > Data List
        Tester Display
        Coolant Temp




    4. Read the value.

      Result
      Display Proceed to
      -40°C (-40°F) A
      140°C (284°F) or more B
      The same as actual engine coolant temperature C
      Tip:

      • If there is an open circuit, the GTS indicates -40°C (-40°F).

      • If there is a short circuit, the GTS indicates 140°C (284°F) or more.


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    CHECK HARNESS AND CONNECTOR (CHECK FOR OPEN)


    1. B00291FC39
      *1 Engine Coolant Temperature Sensor
      *2 ECM
      *a

      Front view of wire harness connector

      (to Engine Coolant Temperature Sensor)

      Disconnect the engine coolant temperature sensor connector.

    2. Connect terminals 1 and 2 of the ECT sensor wire harness side connector.

    3. Connect the GTS to the DLC3.

    4. Turn the ignition switch to ON and turn the GTS on.

    5. Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.


      1. Powertrain > Engine > Data List
        Tester Display
        Coolant Temp




    6. Read the value.

      OK
      140°C (284°F) or higher
      Result
      Proceed to
      OK
      NG

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    CHECK HARNESS AND CONNECTOR (ECM - ENGINE COOLANT TEMPERATURE SENSOR)


    1. Disconnect the engine coolant temperature sensor 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
      C125-2 - C128-21 (THW) Always Below 1 Ω
      C125-1 - C128-29 (ETHW) Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    • OK

      REPLACE ECMClick here

    • NG

      REPAIR OR REPLACE HARNESS OR CONNECTOR

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    CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)


    1. A01SEP6C37
      *1 Engine Coolant Temperature Sensor
      *2 ECM

      Disconnect the engine coolant temperature sensor connector.

    2. Connect the GTS to the DLC3.

    3. Turn the ignition switch to ON and turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Coolant Temp.


      1. Powertrain > Engine > Data List
        Tester Display
        Coolant Temp




    5. Read the value.

      OK
      -40°C (-40°F)
      Result
      Proceed to
      OK
      NG

  5. Click here

    CHECK HARNESS AND CONNECTOR (ECM - ENGINE COOLANT TEMPERATURE SENSOR)


    1. Disconnect the engine coolant temperature sensor 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
      C125-2 or C128-21 (THW) - Body ground and other terminals Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    • OK

      REPLACE ECMClick here

    • NG

      REPAIR OR REPLACE HARNESS OR CONNECTOR