P0111
DTC P0111 INTAKE AIR TEMPERATURE SENSOR1 CIRCUIT RANGE/PERFORMANCEComponent Location:
GENERAL DESCRIPTION
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 5 Volts to the AT sensor. The PCM monitors the voltage across the AT 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 (Cold post start correction), ignition angle correction(Air temperature correction) and idle speed correction(Air-density correction).
DTC DESCRIPTION
Determine if the IAT sensor reeding is skewed high or low. As in the stuck test, the IAT sensor is exposed to conditions such as ample airflow introduction and engine heating that enhance the possibility of ambient temperature change. That helps the diagnostic in its analysis
A skewed condition is suspected only if the IAT at startup differs from the coolant temperature by a minimum threshold on either the high or the low side. If it does not, the skew test dedares a PASS.Otherwise, if IAT & ECT and the coolant temperature is greater than an allowed minimum, the Skew Low Test is executed. This test checks for enough engine load to be present and introduces a delay as long as the skewed condition persists. This allows sufficient airflow introduction and engine heating, and also allows time for the IAT reading to stabilize. If at any time during this delay the absolute difference between the start-up and current IAT exceeds a maximum allowed value (drift check), no reporting is done and the test is disabled (case of vehicle being driven out of a heated garage in to a colder ambience, etc.). Otherwise, once the delay period is over, a fail counter is incremented and as it reaches its threshold, the low test completes and indicates a failure.On the other hand if a passing condition is not present and IAT & ECT, the Skew High Test is called. This test checks for enough engine load to be present and introduces a delay as long as the skewed condition persists. This allows sufficient airflow introduction and engine heating and also allows time for the IAT reading to stabilize. If at any time during this delay the absolute difference between the start-up and current IAT exceeds a maximum allowed value (drift check), no reporting is done and the test is disabled (case of vehicle being driven out of an air conditioned garage into a warmer ambience, etc.). Once the delay period is over and the IAT is greater than a minimum threshold, a fail counter is incremented and as it reaches its threshold, the high test completes and indicates a failure. But if the IAT is less than this threshold, no reporting is done and test is disabled (again protection against case of vehicle being driven out of an air conditioned garage into a warmer ambience and setting a false MIL).
PCM monitors difference MAX. and MIN IATS in order to detect movement in IATS through Start Test and Drive Test while enable condition is met. If PCM detects intake air temperature does not change PCM determines that a fault exists and a DTC is stored. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC Detecting Condition:
Specification:
Schematic Diagram:
Signal Waveform And Data:
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 SCANTOOL DATA
1. IG "OFF" & connect Scantool.
2. ENG "ON" and warm-up the engine to normal operating temperature.
3. Monitor "IATS" item on the service data.
4. Is the "IATS" data displayed correctly?
YES: 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
NO: Go to "Terminal and Connector Inspection" procedure
TERMINAL AND CONNECTOR INSPECTION
1. 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.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "Signal Circuit Inspection" procedure.
SIGNAL CIRCUIT INSPECTION
1. IG "OFF" and disconnect IATS connector.
2. IG "ON" and ENG "OFF"
3. Measure voltage between terminal 4 of IATS harness connector and chassis ground.
Specification : Approx.5 V
4. Is the measured voltage within specification?
YES: Check short to battery in harness.
If O.K, go to "Ground Circuit Inspection" procedure.
If N.G, repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO: Repair open or short to ground in harness and go to "Verification of Vehicle Repair" procedure.
GROUND CIRCUIT INSPECTION
1. IG "OFF" and disconnect IATS connector.
2. Measure voltage terminal 4 of IATS harness connector and chassis ground.
3. Measure voltage terminal 4 and 5 of IATS harness connector.
Specification : Voltage difference between measurement "A" and "B" is below 200mV.
4. Is the measured voltage within specification?
YES: Go to "Component Inspection" procedure.
NO: Repair contact resistance or open in harness and go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Check resistance of IATS
1. IG "OFF" and disconnect IATS connector.
Specification Part 1:
2. Measure resistance between terminal 4 and 5 of IATS connector.(Component Side)
3. Is the measured resistance within specification ?
YES: Go to "Check PCM" as follows.
NO: 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.
2. Check PCM
1. IG "OFF" and connect Scantool.
2. Disconnect IATS connector and connect probe to terminal 4 of IATS harness connector.
3. IG "ON" and ENG "OFF" and simulation Function on Scantool.
4. Simulate voltage at terminal 4 of IATS harness connector.
5. Does the signal value of IAT sensor change according to simulation voltage?
YES: 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.
NO: 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.
NOTE: 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.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions
4. Monitor that all readiness tests have been verified as "Complete"
5. Are any DTCs present?
YES: Go to the applicable trouble shooting procedure.
NO: System is performing to specification at this time.