P0118

DTC P0117, P0118 ECT SENSOR





Component Description





The engine coolant temperature sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the ECM. The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.











CAUTION:
Never use ECM ground terminals when measuring input/output voltage. Doing so may result in damage to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.




On Board Diagnosis Logic
These self-diagnoses have the one trip detection logic.

On Board Diagnosis Logic:

FAIL-SAFE MODE
When the malfunction is detected, the ECM enters fail-safe mode and the MIL illuminates.

FAIL-SAFE MODE:

DTC Confirmation Procedure
1. If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Turn ignition switch ON.
c. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON and wait at least 5 seconds.
3. Check DTC.
4. If DTC is detected, go to P0117.




Wiring Diagram




Diagnosis Procedure
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten ground screws on the body. Refer to Power Supply and Ground Circuit.





OK or NG
OK - GO TO 2.
NG - Repair or replace ground connections.
2.CHECK ECT SENSOR POWER SUPPLY CIRCUIT
1. Disconnect engine coolant temperature (ECT) sensor harness connector.





2. Turn ignition switch ON.





3. Check voltage between ECT sensor terminal 1 and ground with
CONSULT-III or tester.

Voltage: Approximately 5Vm

OK or NG
OK - GO TO 4.
NG - GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
- Harness connector F291, F50
- Harness for open or short between ECM and engine coolant temperature sensor
Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK ECT SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECT sensor terminal 2 and ECM terminal 67. Refer to Wiring Diagram.

Continuity should exist.

4. Also check harness for short to ground and short to power.
OK or NG
OK - GO TO 6.
NG - GO TO 5.
5.DETECT MALFUNCTIONING PART
Check the following.
- Harness connector F291, F50
- Harness for open and short between ECT sensor and ECM
Repair open circuit or short to ground or short to power in harness or connectors.
6.CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to P0117.
OK or NG
OK - GO TO 7.
NG - Replace engine coolant temperature sensor.
7.CHECK INTERMITTENT INCIDENT
Refer to Diagnosis Procedure.
INSPECTION END




Component Inspection

ENGINE COOLANT TEMPERATURE SENSOR
1. Check resistance between engine coolant temperature sensor terminals 1 and 2 as shown in the figure.















2. If NG, replace engine coolant temperature sensor.




Removal and Installation

ENGINE COOLANT TEMPERATURE SENSOR
Refer to Component.