P1111
P1111Component 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 output signal is intermittently over 4.9 V, PCM sets P1111.
DTC Detecting Condition:
Specification:
Signal Waveform:
Schematic Diagram:
Monitor DTC Status
1. Check DTC Status
1. Connect scantool to Data Link Connector(DLC).
2. IG "ON".
3. Select "Diagnostic Trouble Codes(DTCs)" mode, and then Press F5(INFO) to check DTC's information from the DTCs menu
4. Read "DTC Status" parameter.
5. Is parameter displayed "Present fault"?
YES
a. Go to "Terminal and Connector inspection" procedure.
NO
a. 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.
Terminal and Connector Inspection
1. Many malfunctions in the electrical system are caused by poor harness and terminal condition. 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. Check voltage
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 - Go to "Ground Circuit Inspection" procedure.
NO - If the voltage is 0 V, go to "Check open in harness" as follows. If the voltage is more than 5.1 V, go to "Check short to battery in harness" as follows.
2. Check short to battery in harness
1. IG "OFF" and disconnect IATS connector and PCM connector.
2. Measure resistance between terminals 2 and 4 of IATS harness connector.
3. Measure resistance between terminals 1 and 4 of IATS harness connector.
Specification : Infinite
4. Is the measured resistance within specification?
YES - Go to "Component Inspection" procedure.
NO - Repair short to battery in harness and go to "Verification of Vehicle Repair" procedure.
3. Check open in harness
1. IG "OFF" and disconnect IATS connector and PCM connector.
2. Measure resistance between terminal 4 of IATS harness connector and 44 of PCM harness connector.
Specification : below 1 ohm
3. Is the measured resistance within specification?
YES - Go to "Ground Circuit Inspection" procedure.
NO - Repair open in harness and go to "Verification of Vehicle Repair" procedure.
Ground Circuit inspection
1. IG "OFF" and disconnect IATS connector.
2. Measure voltage between terminal 4 of IATS harness connector and chassis ground.
3. Measure voltage between terminals 4 and 5 of IATS harness connector.
Specification : Voltage difference between measurement "A" and "B" is below 200 mV.
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 IATS
1. IG "OFF" and disconnect IATS connector.
2. Measure resistance between terminals 4 and 5 of IATS connector.(Component side)
Specification :
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 IATS 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.
CAUTION: There is a memory reset function on scantool that can erase optional components automatically detected and memorized by PCM. Before or after testing PCM on the vehicle, use this function to reuse the PCM.
Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode
2. Press F5(INFO) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
3. Read "DTC Status" parameter
4. Is parameter displayed "History(Not Present) fault"?
YES - System performing to specification at this time. Clear the DTC
NO - Go to the applicable troubleshooting procedure.