The Engine Coolant Temperature Sensor (ECTS) is located in the engine coolant passage of the cylinder head for detecting the engine coolant temperature. The ECTS uses a thermistor whose resistance changes with the temperature. The electrical resistance of the ECTS decreases as the temperature increases, and increases as the temperature decreases. The reference 5 V in the ECM is supplied to the ECTS via a resistor in the ECM. That is, the resistor in the ECM and the thermistor in the ECTS are connected in series. When the resistance value of the thermistor in the ECTS changes according to the engine coolant temperature, the output voltage also changes.During cold engine operation the ECM increases the fuel injection duration and controls the ignition timing using the information of engine coolant temperature to avoid engine stalling and improve drivability.
DTC DESCRIPTION
ECM sets DTC P0118 if the ECM detects signal voltage higher than the possible range of a properly operating ECTS.
DTC DETECTING CONDITION
Item
Detecting Condition
Possible Cause
DTC Strategy
●
Voltage range check
●
Short to battery in signal harness
●
Open in signal or ground circuit
●
Contact resistance in connections.
●
Faulty ECT sensor
Enable Conditions
●
6 ＜ Battery voltage
●
Time after start ＞ 110sec.＆ intake air temperature ≥ -30℃(-22℉)
Threshold Value
●
Measured coolant temperature ＜ -46℃(-51℉)
Diagnostic Time
●
5 sec.
MIL On Condition
●
2 Driving Cycles
SIGNAL WAVEFORM AND DATA
SPECIFICATION
Temp.(℃)
Temp.(℉)
Resistance(㏀)
-20
-4
14.1 ~ 16.8
0
32
Approx. 5.8
20
68
2.3 ~ 2.6
40
104
Approx. 1.2
60
140
Approx. 0.6
80
176
Approx. 0.3
SCHEMATIC DIAGRAM
MONITOR DTC STATUS
1.
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2.
Press F4(DTAL) to select DTC information from the DTCs menu.
3.
Confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
4.
Read "DTC Status" parameter.
5.
Is parameter displayed "History(Not Present) fault"?
note
-
History (Not Present) fault : DTC occurred but has been cleared.
-
Present fault : DTC is occurring at present time.
▶ Fault is intermittent caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
▶ Go to next step as below.
GROUND CIRCUIT INSPECTION
1.
Ignition "OFF"
2.
Disconnect ECTS connector
3.
Measure resistance between terminal 3 of the sensor harness connector and chassis ground
Specification : Approx. 0Ω
4.
Is resistance within the specification?
▶ Go to next step as below
▶ Repair open circuit and go to "Verification of Vehicle Repair" procedure
SIGNAL CIRCUIT INSPECTION
1.
Check for short to battery in signal harness
(1)
Disconnect ECM connector.
(2)
Ignition "ON" ＆ Engine "OFF"
(3)
Measure voltage between terminal 1 of the sensor harness connector and chassis ground
Specification : Approx. 0V
(4)
Is voltage within the specification?
▶ Go to "Terminal and Connector Inspection" procedure
▶ Check for short to battery or open in signal harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
2.
Check for open in signal harness
(1)
Ignition "OFF"
(2)
Measure resistance between terminal 1 of the sensor harness connector and 15 of the ECM harness connector
Specification : Approx. 0Ω
(3)
Is resistance within the specification?
▶ Go to next step as below
▶ Check for open in signal harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
TERMINAL AND CONNECTOR INSPECTION
1.
Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3.
Has a problem been found?
▶ Check for open in signal harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
▶ Go to next step as below
COMPONENT INSPECTION
1.
Measure resistance between terminals 1 and 3 of the sensor connector(Component side)
Specification :
Temp.(℃)
Temp.(℉)
Resistance(㏀)
-20
-4
14.1 ~ 16.8
0
32
Approx. 5.8
20
68
2.3 ~ 2.6
40
104
Approx. 1.2
60
140
Approx. 0.6
80
176
Approx. 0.3
2.
Is resistance within the specification?
▶ Check for poor connection between ECM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair" procedure
▶ Check ECTS for contamination, deterioration, or damage. Substitute with a known-good ECTS and check for proper operation. If the problem is corrected, replace ECTS and then go to "Verification of Vehicle Repair" procedure
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1.
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2.
Press F4(DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
3.
Read "DTC Status" parameter.
4.
Is parameter displayed "History(Not Present) fault"?
▶ System performing to specification at this time. Clear the DTC
