P1112
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 every 20 sec. under detecting condition, if an ouput signal is below 0.1V for more than 10 sec., PCM sets P1112.
DTC DETECTING CONDITION
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.
SPECIFICATION
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 F4(DTAL) to check DTC's information from the DTCs menu
(4) Read "DTC Status" parameter.
(5) Is parameter displayed "Present fault"?
YES
> Go to "Terminal and connector inspection" procedure.
NO
> 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 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. 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. 5V
(4) Is the measured voltage within specification ?
YES
> Go to "Component Inspection" procedure.
NO
> Go to " Check short to ground in harness" procedure.
2. Check short to ground in harness
(1) IG "OFF" and disconnect IATS connector and PCM connector.
(2) Measure resistance between terminal 4 of IATS harness connector and chassis ground.
(3) Measure resistance between terminals 4 and 5 of IATS harness connector.
(4) Measure resistance between terminals 4 and 3 of IATS harness connector.
Specification : Infinite
(5) Is the measured resistance within specification?
YES
> Go to "Component inspection" procedure.
NO
> Repair short to ground 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 teminals 4 and 5 of IATS connector.(Component side)
Specificaton :
(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 rediness test have been verified as " Complete "
5. Are any DTCs present ?
YES
> Go to the applicable troubleshoooting procedure.
NO
> System is performing to specification at this time.