3.
Monitor "IATS" item on the service data.
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 time correction, ignition timing correction and idle speed correction(Air-density correction).
Checking output signals of IATS every 120 sec. under detecting condition, if an ouput signal is over 4.9V for more than 4 sec., PCM sets P1111.
Item | Detecting Condition | Possible Cause | |
DTC Strategy | ● This code detects a continuous short to high in either the signal circuit or the sensor | ● Poor Connection ● Open or short in signal circuit ● Open in ground circuit ● Faulty IATS ● Faulty PCM | |
Enable Conditions | Case 1 | ● No VSS Fault Active (No P0501) ● No Coolant Short Active Fault Present ● No MAF Active Fault Present ● Engine Air Flow 〈 15 g/s ● Vehicle Speed 〈 25kph ● Engine Coolant Temperature 〉 50℃( 122 °F) ● Engine Running Time 〉 120 sec. | |
Case 2 | ● No VSS Fault Active (No P0501) ● No Coolant Short Active Fault Present ● No MAF Active Fault Present ● Engine Air Flow 〈 15 g/s ● Vehicle Speed 〈 25kph ● Ignition off time 〉 360 min. ● Engine Coolant Temperature 〉 -10℃( 14 °F) ● Engine Running | ||
Threshold value | ● IATS signal 〉 4.9V | ||
Diagnosis Time | ● Continuous (More than 4 sec. failure for every 120 sec. test) | ||
MIL On Condition | ● DTC only (NO MIL ON) | ||
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) | 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 |
IG "OFF" ＆ connect scantool.
ENG "ON" and warm -up the engine to normal operating temperature.
Monitor "IATS" item on the service data.
Is the "IATS" 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 IATS connector.
IG "ON" and ENG "OFF"
Measure voltage between terminal 4 of IATS harness connector and chassis ground.
Specification : Approx. 5V
Is the measured voltage within specification ?
▶ Go to "Ground Circuit Inspection" procedure.
▶ If the voltage is 0V, go to "Check open in harness" as follows. If the voltage 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 IATS connector and PCM connector.
Measure resistance between terminals 2 and 4 of IATS harness connector.
Measure resistance between terminals 1 and 4 of IATS 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 IATS connector and PCM connctor.
Measure resistance between terminal 4 of IATS harness connector and 44 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 IATS connector.
Measure voltage between terminal 4 of IATS harness connector and chassis ground.
Measure voltage between terminals 4 and 5 of IATS 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 contact resistance or open in harness and go to "Verification of Vehicle Repair" procedure.
Check IATS
IG "OFF" and disconnect IATS connector.
Measure resistance between teminals 4 and 5 of IATS connector.(Component side)
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 |
Is the measured resistance within specification ?
▶ Go to "Check PCM" 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 PCM
IG "OFF" and connect scantool.
Disconnect IATS connector and connect probe to terminal 4 of IATS harness connector.
IG "ON" and ENG "OFF" and simulation Function on scantool.
Simulate voltage at terminal 4 of IATS harness connector.
Does the signal value of IAT 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.
