- Open or short in IAT sensor circuit
- IAT sensor (built into MAF meter)
- ECM
| Last Modified: 11-29-2007 | 1.6 C | |
| Service Category: Engine/Hybrid System | Section: Engine Control | |
| Model Year: 2008 | Model: Sequoia | Doc ID: RM000000PF305BX |
| Title: 2UZ-FE ENGINE CONTROL: SFI SYSTEM: DESCRIPTION (2008 Sequoia) | ||
|
DTC |
P0110 |
Intake Air Temperature Circuit Malfunction |
|
DTC |
P0112 |
Intake Air Temperature Circuit Low Input |
|
DTC |
P0113 |
Intake Air Temperature Circuit High Input |
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 driveability.
HINT:
When any of DTCs P0110, P0112 and P0113 are stored, 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.
|
DTC No. |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
P0110 |
Open or short in IAT sensor circuit for 0.5 seconds (1 trip detection logic) |
|
|
P0112 |
Short in IAT sensor circuit for 0.5 seconds (1 trip detection logic) |
|
|
P0113 |
Open in IAT sensor circuit for 0.5 seconds (1 trip detection logic) |
|
HINT:
When any of these DTCs are stored, check the IAT by entering the following menus using the Techstream: Powertrain / Engine / All Data / Intake Air.
|
Temperature Displayed |
Malfunction |
|---|---|
|
-40°C (-40°F) |
Open circuit |
|
140°C (284°F) or higher |
Short circuit |
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 stores 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 stores 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 stores DTC P0112.
If the malfunction is not repaired successfully, a DTC is stored 0.5 seconds after the engine is next started.
MONITOR STRATEGY
|
Related DTCs |
P0110: IAT sensor range check (Fluctuating) P0112: IAT sensor range check (Low voltage) P0113: IAT sensor range check (High voltage) |
|
Required Sensors/Components (Main) |
IAT sensor |
|
Required Sensors/Components (Related) |
- |
|
Frequency of Operation |
Continuous |
|
Duration |
0.5 seconds |
|
MIL Operation |
Immediate |
|
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
|
Monitor runs whenever following DTCs not present |
None |
TYPICAL MALFUNCTION THRESHOLDS
P0110
|
IAT sensor voltage |
Less than 0.18 V, or more than 4.91 V |
P0112
|
IAT sensor voltage [IAT] |
Less than 0.18 V [More than 140°C (284°F)] |
P0113
|
IAT sensor voltage [IAT] |
More than 4.91 V [Less than -40°C (-40°F)] |
COMPONENT OPERATING RANGE
|
IAT sensor voltage [IAT] |
0.18 to 4.91 V [-40 to 140°C (-40 to 284°F)] |
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the Techstream. 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.
PROCEDURE
|
1. |
READ OUTPUT DTC (P0110, P0012 AND P0013) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream ON.
(d) Enter the following menus: Powertrain / Engine / Trouble Codes.
(e) Read DTCs.
Result
|
Result |
Proceed to |
|---|---|
|
P0110 is output |
A |
|
P0112 is output |
B |
|
P0113 is output |
C |
|
|
2. |
READ VALUE USING TECHSTREAM (INTAKE AIR TEMPERATURE) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream ON.
(d) Enter the following menus: Powertrain / Engine / All Data / Intake Air.
(e) Read the value displayed on the Techstream.
OK:
Same as actual Intake Air Temperature (IAT).
Result
|
Result |
Proceed to |
|---|---|
|
-40°C (-40°F) |
A |
|
140°C (284°F) or higher |
B |
|
Same as actual IAT |
C |
HINT:
- If there is an open circuit, the Techstream indicates -40°C (-40°F).
- If there is a short circuit, the Techstream indicates 140°C (284°F) or higher.
|
|
3. |
READ VALUE USING TECHSTREAM (CHECK FOR OPEN IN WIRE HARNESS) |
(a) Disconnect the MAF meter connector.
(b) Connect terminals 4 (THA) and 5 (E2) of the MAF meter wire harness side connector.
(c) Connect the Techstream to the DLC3.
(d) Turn the ignition switch to ON.
(e) Turn the Techstream ON.
(f) Enter the following menus: Powertrain / Engine / All Data / Intake Air.
(g) Read the value displayed on the Techstream.
Standard value:
140°C (284°F) or higher
|
|
4. |
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM) |
(a) Disconnect the MAF meter connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
D3-4 (THA) - D56-73 (THA) |
Always |
Below 1 Ω |
|
D3-5 (E2) - D56-97 (ETHW) |
Always |
Below 1 Ω |
|
|
9. |
PERFORM ACTIVE TEST USING TECHSTREAM (CHECK FOR SHORT IN WIRE HARNESS) |
(a) Disconnect the MAF meter connector.
(b) Connect the Techstream to the DLC3.
(c) Turn the ignition switch to ON.
(d) Turn the Techstream ON.
(e) Enter the following menus: Powertrain / Engine / All Data / Intake Air.
(f) Read the value displayed on the Techstream.
Standard value:
-40°C (-40°F)
|
|
10. |
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM) |
(a) Disconnect the MAF meter connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
D3-4 (THA) or D56-73 (THA) - Body ground |
Always |
10 kΩ or higher |
|
|
|