Component Location
General Description
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 ECM is supplied to the IATS via a resistor in the ECM. That is, the resistor in the ECM 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 ECM corrects basic fuel injection duration and ignition timing.
DTC Description
Checking output signals of IATS under detecting condition, if an ouput signal is intermittently over 4.9V, ECM sets P1111.
DTC Detecting Condition
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 to battery in harness
Open in ground harness
IATS
ECM
|
Enable Conditions | Engine running state
No Vehicle speed sensor fault
No ECTS fault
No MAFS fault
Intake airflow < 15 g/s
Vehicle speed < 25kph(9.3mph)
Engine coolant temperature > 50?(122?)
|
Threshold value | Intake air temperature sensor's voltage > 4.9V
|
Diagnosis Time | Continuous (More than 10 seconds failure for every 20 seconds test)
|
MIL On Condition | NO MIL ON(DTC only)
|
Specification
Temp. (?) | Resistance (k?) | Temp. (?) | Resistance (k?) |
-40 | 95.95 ~ 105.78 | 20 | 3.42 ~ 3.61 |
-20 | 27.4 ~ 29.77 | 40 | 1.43 ~ 1.5 |
0 | 9.08 ~ 9.72 | 60 | 0.66 ~ 0.69 |
10 | 5.49 ~ 5.83 | 80 | 0.33 ~ 0.34 |
Diagnostic Circuit Diagram
Signal Waveform & Data
Fig 1) Normal waveform of IATS at 43? (109?)
Fig 2) Normal data of IATS(53?) & ECTS & EOTS at ig on
Fig 3) Normal data of IATS(82?) & ECTS & EOTS after warming up.
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. 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.