P0117

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-diagnosis have the one trip detection logic.






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









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 and wait at least 5 seconds.
3. Check DTC.
4. If DTC is detected, go to "Diagnosis Procedure".




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





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 5V

OK or NG
OK - GO TO 3.
NG - Repair open circuit or short to ground or short to power in harness or connectors.
3.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 4.
NG - Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK ENGINE COOLANT TEMPERATURE SENSOR
Refer to P0117.
OK or NG
OK - GO TO 5.
NG - Replace engine coolant temperature sensor.
5.CHECK INTERMITTENT INCIDENT
Refer to 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.