3.
Has a problem been found?
Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Go to "Signal Circuit Inspection" procedure.
IATS (Intake Air Temperature Sensor) is intergrated in MAF sensor.
This part employs a thermistor (NTC) which is sensitive to changes in temperature.
The electric resistance of a thermistor decreases as the temperature increases, and increases as the temperature decreases.
The power source in the ECM is supplied to the IATS via a resistor in the ECM.
The ECM judges intake air temperature by the sensor output voltage and is used for injection quantity correction, injection time correction, starting fuel quantity correction as a compensation signal.
If the signal is above threshold value, the ECM judged this as a fault and DTC is set.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Signal check, high | ● Short to ground in signal circuit ● Open in signal circuit ● Open in ground circuit ● Faulty IATS ● Faulty ECM |
Enable Conditions | ● Ignition on | |
Threshold Value | ● Output signal ＞ 4.9V | |
Diagnostic Time | ● 2 sec. | |
MIL Fuel Limit Fuel Cut EGR Off | ● No ● No ● No ● Yes | |
Fail safe | ● Engine air temperature is fixed at value of 60°C by ECM |
IATS | |||
Temperature (°C) | 20 | 40 | 60 |
Resistance (kΩ) | 2.29 ~ 2.55 | 1.1 ~ 1.2 | 0.56 ~ 0.65 |
Ignition "OFF" & Engine "OFF".
Install Scantool and Engine "ON".
Monitor Intake Air Temperature Sensor on Current data.
Fig 1) Signal decreases with increasing sensor temperature and increases with decreasing sensor temperature : Approx. 2V at 20°C(68°F)
Is Current data 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, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification vehicle Repair" procedure.
▶ Go to "W/Harness 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 for short to battery in signal harness
Ignition "OFF".
Disconnect IAT sensor connector.
Measure voltage between terminal 5 of the sensor harness connector and chassis ground.
Specification : Approx. 5V
Is the measured voltage within specifications?
▶ Go to "Check for open in signal harness" as below.
▶ Check for short to battery in signal harness.
Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Check for open in signal harness
Ignition "OFF"
Disconnect IAT sensor connector and ECM connector.
Measure resistance between terminal 5 of the sensor harness connector and terminal 5 of ECM harness connector.
Specification : Approx. below 1Ω
Is the measured resistance within specifications?
▶ Go to "Signal Circuit Inspection" procedure.
▶ Check for open in harness.
Repair as necessary and go to "Verification of Vehicle Repair" procedure.
Ignition "OFF".
Disconnect IAT sensor connector and ECM connector.
Measure resistance between terminal 3 of the sensor harness connector and terminal 7 of ECM harness connector.
Specification : Approx. below 1Ω
Is the measured resistance within specifications?
▶ Go to "Component Inspection" procedure.
Check for open in ground harness.
Repair as necessary and go to "Verification of Vehicle Repair" procedure .
Check IATS
Ignition "OFF" & Engine "OFF".
Disconnect IATS connector.
Monitor resistance between terminal 3 and 5 of IATS connector(Component Side).
Temperature (°C) | 20 | 40 | 60 |
Resistance (KΩ) | 2.29 ~ 2.55 | 1.1 ~ 1.2 | 0.56 ~ 0.65 |
Is the measured resistance within specifications?
▶ Substitute with a known-good ECM and check for proper operation.
If the problem is corrected, replace ECM and then 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 then 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 and then clear DTC.
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.
