Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Intake air temperature circuit / Circuit description
Toyota Corolla (E120): Circuit description
The intake air temperature (iat) sensor, mounted on the mass air flow (maf) sensor, monitors the intake air temperature. The iat sensor has a thermistor that varies its resistance depending on the temperature of the intake air. When the air temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. The variations in resistance are reflected as voltage changes to the ecm terminal.
(See fig. 1).
The intake air temperature sensor is connected to the ecm.
The 5 v power source voltage in the ecm is applied to the intake air temperature sensor from terminal tha (thar) via resistor r.
That is, the resistor r and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes in accordance with changes in the intake air temperature, the potential at terminal tha (thar) also changes. Based on this signal, the ecm increases the fuel injection volume to improve the drive ability during cold engine operation.
|
Dtc no. |
Proceed to |
Dtc detection condition |
Trouble area |
| P0110 | Step 1 | Open or short in intake air temperature sensor circuit for 0.5 Seconds |
|
| P0112 | Step 4 | Short in intake air temperature sensor circuit for 0.5 Seconds | |
| P0113 | Step 2 | Open in intake air temperature sensor circuit for 0.5 Seconds |
Hint
: after confirming dtc p0110, p0112 or p0113, confirm the intake air temperature in the ”diagnosis / enhanced obd ii / data list / all” using the hand–held tester or the obd ii scan tool.
Monitor description
The ecm monitors the sensor voltage and uses this value to calculate the intake air temperature. When the sensor output voltage deviates from the normal operating range, the ecm interprets this as a fault in the iat sensor and sets a dtc.
Example: when the sensor voltage output equal to –40 c (–40 °F) or more than 140 c (284 °F).
Monitor strategy
Typical enabling conditions
Typical malfunction thresholds
Component operating range
Wiring diagram
Other materials:
Check dlc3
The vehicle’s ecm uses the iso 9141–2 for communication
protocol. The terminal arrangement of the dlc3 complies
with sae j1962 and matches the iso 9141–2 format.
Hint:
if the display shows unable to connect to vehicle
when you have connected the cable of the obd ii scan tool or
the h ...
Inspection procedure
1 Check operation(starter)
Check that the starter operates normally and that the engine starts.
2 Input signal check
See input signal check on page 05–745.
check the indicator light when shifting into except d position.
Ok:
the indicator light goes off when shifting ...
Using the radio (Multimedia system)
Radio operation
Select “AM” or “FM” on the audio source selection screen to begin listening
to the radio.
Audio control screen
Pressing the “AUDIO” button displays the audio control screen from any screens
of the selected source.
1 Audio source selection screen appears
2 Preset ...