DTC    P0115    Engine Coolant Temperature Circuit Malfunction

DTC    P0117    Engine Coolant Temperature Circuit Low Input

DTC    P0118    Engine Coolant Temperature Circuit High Input

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DESCRIPTION

A thermistor is built into the Engine Coolant Temperature (ECT) sensor, of which the resistance value varies according to the ECT.
The structure of the sensor and its connection to the ECM are the same as those of the Intake Air Temperature (IAT) sensor.

HINT:
When any of DTCs P0115, P0117 and P0118 are set, the ECM enters fail-safe mode. During fail-safe mode, the ECT is estimated to be 80°C (176°F) by the ECM. Fail-safe mode continues until a pass condition is detected.


DTC No.
Proceed to
DTC Detection Condition
Trouble Area
P0115
Step 1
Open or short in Engine Coolant Temperature (ECT) sensor circuit for 0.5 seconds (1 trip detection logic)
  1. Open or short in ECT sensor circuit
  1. ECT sensor
  1. ECM
P0117
Step 4
Short in Engine Coolant Temperature (ECT) sensor circuit for 0.5 seconds (1 trip detection logic)
  1. Short in ECT sensor
  1. ECT sensor
  1. ECM
P0118
Step 2
Open in Engine Coolant Temperature (ECT) sensor circuit for 0.5 seconds (1 trip detection logic)
  1. Open in ECT sensor circuit
  1. ECT sensor
  1. ECM

HINT:
When any of these DTCs are set, check the ECT by entering the following menus on the intelligent tester: Power train / Engine / Data List / Coolant Temp.


Temperature Displayed
Malfunction
-40°C (-40°F)
Open circuit
140°C (284°F) or higher
Short circuit

MONITOR DESCRIPTION

The Engine Coolant Temperature (ECT) sensor is used to monitor the ECT. The ECT sensor has a thermistor with a resistance that varies according to the temperature of the engine coolant. When the coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are reflected in the output voltage from the sensor. The ECM monitors the sensor voltage and uses this value to calculate the ECT. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the ECT sensor and sets a DTC.
Example:
If the sensor output voltage is -40°C (-40°F) for 0.5 seconds or more, the ECM determines that there is an open in the ECT sensor circuit, and sets DTC P0118. Conversely, if the voltage output is more than 140°C (284°F) for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit, and sets DTC P0117.
If the malfunction is not repaired successfully, a DTC is set 0.5 seconds after the engine is next started.

WIRING DIAGRAM


A110108E02


INSPECTION PROCEDURE

HINT:
  1. If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
  1. Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions 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, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

1.READ VALUE USING INTELLIGENT TESTER (ENGINE COOLANT TEMPERATURE)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Coolant Temp.

  1. Read the value displayed on the tester.

    Standard:
    Between 80°C and 97°C (176°F and 207°F) with warm engine.


Result:

Temperature Displayed
Proceed to
-40°C (-40°F)
A
140°C (284°F) or higher
B
Between 80°C and 97°C (176°F and 207°F)
C

HINT:
  1. If there is an open circuit, the intelligent tester indicates -40°C (-40°F).
  1. If there is a short circuit, the intelligent tester indicates 140°C (284°F) or higher.



B
Go to step 4

C
CHECK FOR INTERMITTENT PROBLEMS
A


2.READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN WIRE HARNESS)
A107691E04

  1. Disconnect the E40 Engine Coolant Temperature (ECT) sensor connector.

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

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Coolant Temp.

  1. Read the value displayed on the tester.

    Standard:
    140°C (284°F) or higher.

  1. Reconnect the ECT sensor connector.



OK
CONFIRM GOOD CONNECTION TO SENSOR. IF OK, REPLACE ENGINE COOLANT TEMPERATURE SENSOR
NG


3.READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN ECM)
A107688E04

  1. Disconnect the E40 ECT sensor connector.

  1. Connect terminals THW and E2 of the E6 and E8 ECM connector.

    HINT:
    Before checking, do visual and contact pressure checks on the ECM connector.

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Coolant Temp.

  1. Read the value displayed on the tester.

    Standard:
    140°C (284°F) or higher.

  1. Reconnect the ECT sensor connector.



OK
REPAIR OR REPLACE HARNESS AND CONNECTOR
NG

CONFIRM GOOD CONNECTION TO ECM. IF OK, REPLACE ECM 

4.READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS)
A084869E12

  1. Disconnect the E40 ECT sensor connector.

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Coolant Temp.

  1. Read the value displayed on the tester.

    Standard:
    -40°C (-40°F)

  1. Reconnect the ECT sensor connector.



OK
REPLACE ENGINE COOLANT TEMPERATURE SENSOR
NG


5.READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN ECM)
A107692E03

  1. Disconnect the E40 ECT sensor connectors.

  1. Disconnect the E6 and E8 ECM connectors.

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Turn the tester ON.

  1. Enter the following menus: Power train / Engine / Data List / Coolant Temp.

  1. Read the value displayed on the tester.

    Standard:
    -40°C (-40°F)

  1. Reconnect the ECM connector.



OK
REPAIR OR REPLACE HARNESS AND CONNECTOR
NG

REPLACE ECM