Description
The intake air temperature (iat) sensor, mounted on the mass air flow (maf) meter, monitors the iat.
The iat sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the iat is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ecm as voltage changes (see fig. 1).
The iat sensor is powered by a 5 v supply from the tha terminal of the ecm, via resistor r.
Resistor r and the iat sensor are connected in series. When the resistance value of the iat sensor changes, according to changes in the iat, the voltage at terminal tha also varies. Based on this signal, the ecm increases the fuel injection volume when the engine is cold to improve drivability.
Hint: when any of dtcs p0110, p0112 and p0113 are set, the ecm enters fail-safe mode. During fail-safe mode, the iat is estimated to be 20°c (68°f) by the ecm. Fail-safe mode continues until a pass condition is detected.
Hint:
When any of these dtcs are set, check the iat by selecting the following menu items on the intelligent tester: diagnosis / enhanced obd ii / data list / primary / intake air.
Monitor description
The ecm monitors the sensor voltage and uses this value to calculate the iat. When the sensor output voltage deviates from the normal operating range, the ecm interprets this as a malfunction in the iat sensor and sets a dtc.
Example: if the sensor output voltage is more than 4.91 V for 0.5 Seconds or more, the ecm determines that there is an open in the iat sensor circuit, and sets dtc p0113. Conversely, if the output voltage is less than 0.18 V for 0.5 Seconds or more, the ecm determines that there is a short in the sensor circuit, and sets dtc p0112.
If the malfunction is not repaired successfully, a dtc is set 0.5 Seconds after the engine is next started.
Monitor strategy
Typical enabling conditions
Typical malfunction thresholds
Component operating range
Wiring diagram
Inspection procedure
Hint:
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
Result
Standard: same as actual intake air temperature (iat).
Result
Hint:
Standard value: 140°c (284°f) or higher
Standard resistance
Confirm good connection to ecm. If ok, replace ecm
Standard value: -40°c (-40°f)
Standard resistance
Removal
(2006/01- )
Remove front wheel
Drain automatic transaxle fluid
Drain the automatic transaxle fluid for u140f (see
page ax-147).
Drain the automatic transaxle fluid for u241e (see
page ax-146).
Drain the automatic transaxle fluid for u151e (see
page ax-172).
Remove front axle hub nut ( ...
Freeze frame data
Freeze frame data
Notice:
It is difficult to show the specified values
(judgment values) clearly because freeze frame
data values change significantly due to
differences in measurement conditions,
surroundings, or vehicle conditions. For this
reason, there may be a problem even w ...
Shift lock system
Parts location
System diagram
On-vehicle inspection
Check shift lock operation
Move the shift lever to p.
Turn the ignition switch off.
Check that the shift lever cannot be moved to any
position other than p.
Turn the ignition switch on, depress the brake
pedal and chec ...