3.
Monitor "IATS" parameter on scantool.
The Intake Air Temperature (IAT) sensor measures the temperature of engine intake air. The Intake Air Temperature (IAT) sensor is a thermistor (a variable resistor that changes along with outside air temperature) in series with a fixed resistor in the PCM. The PCM applies 5V to the IAT sensor. The PCM monitors the voltage across the IAT sensor and converts it into a temperature reading. When the outside air temperature is cold the IAT sensor resistance is high, and when the outside air temperature is warm the IAT sensor resistance is low. Therefore, when the air temperature is cold the PCM will receive a high voltage input, and when the air temperature is warm the PCM will receive a low voltage input. The signal from IAT sensor is used for injection duration correction, ignition timing correction and idle speed correction(Air-density correction).
If measured temperature is higher than the maximum threshold value during 2sec, ECM sets DTC P0112.
(In this case, the input signal voltage is the minimum threshold vaue.)
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Signal check, high | ● Poor connection ● Open or short to power in signal circuit ● Open in ground circuit ● IATS ● ECM |
Enable Conditions | ● Idle and no fuel cut-off ● Time after engine start 〉 18s ● Integrated air mass 〉 0.27kg ● Increase of measured temp. after start 〈 1.5℃ | |
Threshold Value | ● Measured temperature 〈 -43.5℃ | |
Diagnostic Time | ● 2 sec | |
MIL | ● ON |
Connect scantool to DLC(Data Link Cable).
Warm up the engine to normal operating temperature.
Monitor "IATS" parameter on scantool.
Is the "IATS" parameter displayed correctly?
▶ 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, poorconnection, ending, corrosion, contamination, deterioration, or damage. Repair or replace asnecessary 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 open in harness.
IG "OFF".
Disconnect IATS connector.
IG "ON" ＆ ENG "OFF"
Measure voltage between terminal 3 of IATS harness connector and chassis ground.
Specification : Approx. 5V
Is the measured voltage within specification?
▶ Go to "Check short to ground in harness" as follows.
▶ Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
Check short to ground in harness.
IG "OFF".
Disconnect IATS and ECM connector.
Measure resistance between terminal 3 and 4 of IATS harness connector.
Specification : Infinite
Is the measured resistance within specification?
▶ Go to "Ground Circuit Inspection" procedure.
▶ Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
IG "OFF".
Disconnect IATS connector.
IG "ON" ＆ ENG "OFF"
Measure voltage between terminal 3 of IATS harness connector and chassis ground(A)
Measure voltage between terminal 3 and 4 of IATS harness connector. (B)
Specification : "A" - "B" = Below 200mV
Is the measured voltage within specification?
▶ Go to "Component Inspection" procedure.
▶ Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
Check IATS resistance.
IG "OFF".
Disconnect IATS connector.
Measure resistance between terminal 3 and 4 of IATS connector(Component Side)
Specification :
Temperature [℃] | Temperature [℉] | Resistance [Ω] |
-40.0 | -40.0 | 40.93 ~ 48.35 |
-20.0 | -4.0 | 13.89 ~ 16.03 |
0.0 | 32.0 | 5.38 ~ 6.09 |
20.0 | 68.0 | 2.31 ~ 2.57 |
40.0 | 104.0 | 1.08 ~ 1.20 |
60.0 | 140.0 | 0.54 ~ 0.62 |
80.0 | 176.0 | 0.29 ~ 0.34 |
Is the measured resistance within specification ?
▶ Go to "Check ECM" as follows.
▶ 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.
Check ECM.
IG "OFF" and disconnect MAFS/MAPS connector.
Connect scantool and Key "ON".
Select simulation function on scantool.
Simulate voltage at terminal 3 of IATS signal connector.
Does the signal value of IATS 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 "Verificationof Vehicle Repair" procedure.
▶ Substitute with a known - good ECM and check for proper operation.
▶ If the problem is corrected, replace ECM and go to "Verification of Vehicle Repair" procedure.
After a repair, it is essential to verify that the fault has been corrected.
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
Clear the DTCs and Operate the vehicle within DTC Enable conditions in General information.
Are any DTCs present ?
▶ Go to the applicable troubleshooting procedure.
▶ System is performing to specification at this time.
