Toyota Sienna Service Manual: Intake Air Temperature Sensor Gradient Too High
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 becomes low, the resistance of the thermistor increases. When the temperature becomes 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.
MONITOR DESCRIPTION
The ECM performs OBD II monitoring based on the values from the intake air temperature sensor. If there is no change in the sensor value, the ECM will not be able to perform OBD II monitoring or will misdiagnose that there is a malfunction in the sensor. The ECM detects the stuck intake air temperature sensor value by performing monitoring after the ignition switch is turned off or the ignition is started (short soak or long soak).
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
WIRING DIAGRAM
Refer to DTC P0110 (See page ES-126).
INSPECTION PROCEDURE
1 CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0111)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
(e) Read the DTCs.
Result
HINT: If any DTCs other than P0111 are output, troubleshoot those DTCs first.
GO TO DTC CHART (See page ES-56)
Intake Air Temperature Circuit
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 accord ...
Engine Coolant Temperature Circuit
DESCRIPTION
A thermistor is built into the Engine Coolant Temperature (ECT) sensor, of
which the resistance value
varies according to the ECT.
The structure of the sensor and its connection ...
Other materials:
ECM / PCM Internal Engine Off Timer Performance
DTC P2610 ECM / PCM Internal Engine Off Timer Performance
DTC SUMMARY
DESCRIPTION
To ensure the accuracy of the EVAP (Evaporative Emission) monitor values, the
soak timer, which is built
into the ECM, measures 5 hours (+/- 15 minutes) from when the ignition switch is
turned off, before t ...
Torque Converter Clutch Solenoid Circuit
DESCRIPTION
The shift solenoid valve DSL is turned "ON" and "OFF" by signals from the ECM
in order to control the
hydraulic pressure operation, the lock-up relay valve, which then controls
operation of the lock-up clutch.
MONITOR DESCRIPTION
Torque converter lock-up i ...
What to do if... (Troubleshooting)
If there is a problem with the hands-free system or a Bluetooth®
device, first check the table below.
When using the hands-free system with a Bluetooth® device
The hands-free system or Bluetooth® device does not
work.
The connected device may not be a compatible Bl ...
