Dtc P0115 Engine Coolant Temperature Circuit

Engine. Lexus Gs430, Gs300. Uzs190 Grs190
3Uz-Fe Engine Control System. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

MONITOR DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

READ DATA LIST (ENGINE COOLANT TEMPERATURE)

READ DATA LIST (CHECK FOR OPEN IN WIRE HARNESS)

READ DATA LIST (CHECK FOR OPEN IN ECM)

READ DATA LIST (CHECK FOR SHORT IN WIRE HARNESS)

READ DATA LIST (CHECK FOR SHORT IN WIRE HARNESS)

DTC P0115 Engine Coolant Temperature Circuit

DTC P0117 Engine Coolant Temperature Circuit Low Input

DTC P0118 Engine Coolant Temperature Circuit High Input


DESCRIPTION


  1. Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit
    A thermistor is built into the Engine Coolant Temperature (ECT) sensor and changes the resistance value according to the engine coolant temperature.
    The structure of the sensor and connection to the ECM is the same as the Intake Air Temperature (IAT) sensor.
    HINT:
    If the ECM detects the DTC P0115, P0117 or P0118, it operates the fail-safe function in which the ECT is assumed to be 80°C (176°F).

DTC No.
DTC Detection Condition
Trouble Area
P0115
Open or short in ECT sensor circuit for 0.5 seconds (1 trip detection logic)
  1. Open or short in ECT sensor circuit
  2. ECT sensor
  3. ECM
P0117
Short in ECT sensor circuit for 0.5 seconds (1 trip detection logic)
  1. Open or short in ECT sensor circuit
  2. ECT sensor
  3. ECM
P0118
Open in ECT sensor circuit for 0.5 seconds (1 trip detection logic)
  1. Open or short in ECT sensor circuit
  2. ECT sensor
  3. ECM
HINT:
Confirm the ECT using the intelligent tester. Enter the following menus: Powertrain / Engine / Data List / Primary / Coolant Temp.

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

MONITOR DESCRIPTION

The ECT sensor is used to monitor the engine coolant temperature. The ECT sensor has a thermistor that varies its resistance depending on 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. The 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:
When the ECM calculates that the ECT is -40°C (-40°F) (P0118) or more than 140°C (284°F) (P0117) and that either condition continues for 0.5 seconds or more, the ECM will set a DTC.
This monitor runs for 0.5 seconds after the engine switch is turned on (IG).

WIRING DIAGRAM


Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit


INSPECTION PROCEDURE

1.READ DATA LIST (ENGINE COOLANT TEMPERATURE)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG) and turn the tester ON.

  1. Enter the following menus: Powertrain / Engine / Data List / Primary / Coolant Temp.

  1. Read the values.

    Standard:
    Same value as the actual ECT.

Result:

Engine Coolant Temperature
Proceed to
-40°C (-40°F)
A
140°C (284°F) or more
B
OK (same as present temperature)
C
HINT:
If there is an open circuit, the intelligent tester indicates -40°C (-40°F).
If there is a short circuit, the intelligent tester indicates 140°C (284°F) or more.


B
Go to step 4

C
CHECK FOR INTERMITTENT PROBLEMS
A


2.READ DATA LIST (CHECK FOR OPEN IN WIRE HARNESS)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit

  1. Disconnect the E40 ECT sensor connector.

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

  1. Turn the engine switch on (IG).

  1. Read the value.

    Standard:
    140°C (284°F) or more


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


3.READ DATA LIST (CHECK FOR OPEN IN ECM)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit

  1. Disconnect the E40 ECT sensor connector.

  1. Connect the E6 and E8 ECM connectors.

    HINT:
    Before checking, do a visual and contact pressure check for the ECM connector.

  1. Turn the engine switch on (IG).

  1. Read the value.

    Standard:
    140°C (284°F) or more


NG
CONFIRM GOOD CONNECTION AT ECM. IF OK, REPLACE ECM
OK

REPAIR OR REPLACE HARNESS AND CONNECTOR

4.READ DATA LIST (CHECK FOR SHORT IN WIRE HARNESS)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit

  1. Disconnect the E40 ECT sensor connector.

  1. Turn the engine switch on (IG).

  1. Read the value.

    Standard:
    -40°C (-40°F)


OK
REPLACE ENGINE COOLANT TEMPERATURE
NG


5.READ DATA LIST (CHECK FOR SHORT IN WIRE HARNESS)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System. Dtc P0115 Engine Coolant Temperature Circuit

  1. Disconnect the E40 ECT sensor connector.

  1. Disconnect the E6 and E8 ECM connectors.

  1. Turn the engine switch on (IG).

  1. Read the value.

    Standard:
    -40°C (-40°F)


NG
REPLACE ECM
OK

REPAIR OR REPLACE HARNESS AND CONNECTOR