The Intake Air Temperature Sensor (IATS) is installed into the Mass Air Flow Sensor (MAFS). The IATS uses a thermistor whose resistance changes with the temperature. The electrical resistance of the IATS decreases as the temperature increases, and increases as the temperature decreases. The 5 V power source in the PCM is supplied to the IATS via a resistor in the PCM. That is, the resistor in the PCM and the thermistor in the IATS are connected in series. When the resistance value of the thermistor in IATS changes according to the intake air temperature, the signal voltage also changes. Using this signal, the information of the intake air temperature, the PCM corrects basic fuel injection duration and ignition timing.
DTC DESCRIPTION
PCM monitors temperature difference betwen MAX. and MIN IATS in order to detect movement in IATS not only Start Test but Drive Test while enable condition is met. If PCM detects intake air temperature changes less than 5.4 °F PCM determines that a fault exists and a DTC is stored.
DTC DETECTING CONDITION
Item
Detecting Condition
Possible cause
DTC
Strategy
Case 1
●
Start Test: Monitors the difference between max and min IAT in order to detect movement in IAT for a certain time.
●
Faulty IATS
Case 2
●
Drive test: Performs the max and min delta check while driving under load for a length of time followed by an idle for a certain time.
Enable Conditions
●
Engine soak time ＞ 360min
●
Engine running
●
No fault present
●
IAT stored previous trip
●
No IAT Tests pending
Thresh
old
value
Case 1
●
Max IAT - Min IAT ≤ 3℃(5.4 °F)
Case 2
●
Continuous (10 min.)
MIL On Condition
●
No MIL ON (DTC only)
SPECIFICATION
Temp. (℃/℉)
Resistance (kΩ)
Temp. (℃/℉)
Resistance (kΩ)
-40(-40)
95.95 ~ 105.78
20(68)
3.42 ~ 3.61
-20(-4)
27.4 ~ 29.77
40(104)
1.43 ~ 1.5
0(32)
9.08 ~ 9.72
60(140)
0.66 ~ 0.69
10(50)
5.49 ~ 5.83
80(176)
0.33 ~ 0.34
SCHEMATIC DIAGRAM
SIGNAL WAVEFORM AND DATA
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.
MONITOR DTC STATUS
1.
Check DTC Status
(1)
Connect scantool to Data Link Connector(DLC).
(2)
IG "ON".
(3)
Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.
(4)
Read "DTC Status" parameter.
(5)
Is parameter displayed "Present fault"?
▶ Go to "Component Inspection" procedure.
▶ 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.
COMPONENT INSPECTION
■ Check resistance of IATS
1.
IG "OFF" and disconnect IATS connector.
2.
Measure resistance between signal and ground terminals of IATS connector after checking out the temperature of IATS with scantool.
Specificaton :
Temp. (℃/℉)
Resistance (kΩ)
Temp. (℃/℉)
Resistance (kΩ)
-40(-40)
95.95 ~ 105.78
20(68)
3.42 ~ 3.61
-20(-4)
27.4 ~ 29.77
40(104)
1.43 ~ 1.5
0(32)
9.08 ~ 9.72
60(140)
0.66 ~ 0.69
10(50)
5.49 ~ 5.83
80(176)
0.33 ~ 0.34
3.
Is the measured resistance within specification ?
▶ Go to "Verification of Vehicle Repair" procedure.
▶ Substitute with a known - good IATS and check for proper operation. If the problem is corrected, replace IATS and 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 scantool and select "DTC" button.
2.
Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". 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
