P0118

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:
Do not 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 lights up.









DTC Confirmation Procedure
1. If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next step.
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.
3. Wait at least 5 seconds.
4. Check DTC.
5. If DTC is detected, go to P0117.




Diagnosis Procedure
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three 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 (1) harness connector.





2. Turn ignition switch ON.





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

Voltage: Approximately 5V

OK or NG
OK - GO TO 4.
NG - GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
- Harness connector F26, F101
- 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 F26, F101
- 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 How to Check Terminal and Intermittent Incident.
>> 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.