3.
Monitor "Monitor "ECTS" status on the service data." item on the service data.
The Engine Coolant Temperature(ECT) Sensor measures the temperature of engine coolant. The Engine Coolant Temperature (ECT) Sensor is located near the thermostat housing of the cylinder head. ECT Sensor is a thermistor (A Variable Resistor that Changes Along with ECT) in series with a fixed resistor in the Engine Control Module (PCM). The PCM applies 5 volts to the ECT sensor. The PCM monitors the voltage across the ECT sensor and converts it into a temperature reading. When the engine is cold the ECT sensor resistance is high, and when the engine is warm the ECT sensor resistance is low. Therefore, when the engine is cold the PCM will receive a high voltage input, and when the engine is warm the PCM will receive a low voltage input. The signal from ECT sensor is used for Injection, ignition timing, idle speed and cooling fan control.
Checking output signals from ECTS every 80 sec. under detecting condition, if an output signal is above 4.9V for more than 40 sec., PCM sets P0118. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
Item | Detecting Condition | Possible cause | |
DTC Strategy | ● Open, Signal high | ● Poor connection ● Open or short to battery in signal harness ● Open in ground harness ● ECTS ● PCM | |
Enable Conditions | Case 1 | ● Time after start-up 〉120 sec. | |
Case 2 | ● Time from IG "OFF" to IG "ON" 〉 360 min. ● Intake air temperature ≥ -10℃(14℉) ● Engine running state | ||
Threshold value | ● Engine coolant temperature sensor's voltage 〉4.9V | ||
Diagnosis Time | ● Continuous (More than 40 sec. failure for every 80 sec. test) | ||
MIL On Condition | ● 2 Driving Cycle | ||
The output signals of IATS ＆ ECTS change smoothly without any rapid changes. Those have almost same characteristic signal during the early period after start. It means that the temperatures of intake air and engine coolant are depended on the temperature of atmosphere. Meanwhile, during the warming up, the output signal of ECTS is going up increasingly. but, the output signal of IATS changes a little bit. even it may not change almost. It means that the heat of engine does not affect on the temperature of intake air.
Temp. (℃/℉) | Resistance (kΩ) | Temp. (℃/℉) | Resistance (kΩ) | ||||
-40(-40) | 48.14 | 40(104) | 1.15 | ||||
-20(-4) | 14.13 ~ 16.83 | 60(140) | 0.59 | ||||
0(32) | 5.79 | 80(176) | 0.32 | ||||
20(68) | 2.31 ~ 2.59 |
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IG "OFF" ＆ connect scantool.
ENG "ON" and warm -up the engine to normal operating temperature.
Monitor "Monitor "ECTS" status on the service data." item on the service data.
Is the "ECTS" data displayed correctly ?
▶ Fault is intermittent caused by poor contact in the sensor’s and/or PCM’s connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
▶ Go to "Terminal and connector inspection" procedure
Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure
▶ Go to "Signal Circuit Inspection" procedure.
Check voltage
IG "OFF" and disconnect ECTS connector.
IG "ON" and ENG "OFF"
Measure voltage between terminal 3 of ECTS harness connector and chassis ground.
Specification : Approx. 5V
Is the measured voltage within specification ?
▶ Go to "Ground Circuit Inspection" procedure.
▶ If voltage is 0V, go to "Check open in harness" as follows. If it is more than 5.1V, go to "Check short to battery in harness" as follows
Check short to battery in harness
IG "OFF" and disconnect ECTS connector and PCM connector.
Measure resistance between terminals 2 and 3 of ECTS harness connector.
Specification : Infinite
Is the measured resistance within specification?
▶ Go to "Component Inspection" procedure.
▶ Repair short to battery in harness, and go to "Verification of Vehicle Repair" procedure.
Check open in harness
IG "OFF" and disconnect ECTS connector and PCM connector.
Measure resistance between terminal 3 of ECTS harness connector and terminal 7 of PCM harness connector.
Specification : Below 1Ω
Is the measured resistance within specification?
▶ Go to "Ground Circuit Inspection" procedure.
▶ Repair open in harness, and go to "Verification of Vehicle Repair" procedure.
IG "OFF" and disconnect ECTS connector.
Measure voltage between terminal 3 of ECTS harness connector and chassis ground.
Measure voltage between terminals 1 and 3 of ECTS harness connector.
Specification : Voltage difference between measurement "A" and "B" is below 200mV.
Is the measured voltage within specification?
▶ Go to "Component Inspection" procedure.
▶ Repair open or contact resistance in harness, and go to "Verification of Vehicle Repair" procedure.
Check ECTS
IG "OFF" and disconnect ECTS connector.
Measure resistance between terminals 1 and 3 of ECTS connector.(Component side)
Temp. (℃/℉) | Resistance (kΩ) | Temp. (℃/℉) | Resistance (kΩ) | ||||
-40(-40) | 48.14 | 40(104) | 1.15 | ||||
-20(-4) | 14.13 ~ 16.83 | 60(140) | 0.59 | ||||
0(32) | 5.79 | 80(176) | 0.32 | ||||
20(68) | 2.31 ~ 2.59 |
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Is the measured resistance within specification?
▶ Go to "Check PCM" as follows.
▶ Substitute with a known - good ECTS and check for proper operation. If the problem is corrected, replace ECTS and go to "Verification of Vehicle Repair" procedure.
Check PCM
IG "OFF" and connect scantool.
Connect probe to terminal 3 of ECTS harness connector.
IG "ON" and ENG "OFF" and simulation Function on scantool.
Simulate voltage at terminal 3 of ECTS harness connector.
Does the signal value of ECT sensor change according to simulation voltage ?
▶ Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
▶ Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. Before or after testing PCM on the vehicle, use this function to reuse the PCM on the others.
After a repair, it is essential to verify that the fault has been corrected.
Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
Using a Scantool, Clear the DTCs
Operate the vehicle within conditions noted in the freeze frame data or enable conditions
Monitor that all rediness test have been verified as " Complete "
Are any DTCs present ?
▶ Go to the applicable troubleshoooting procedure.
▶ System is performing to specification at this time.
