The Intake Air Temperature (IAT) sensor is built into the charge air cooler and senses the IAT. A built-in thermistor in the sensor changes its resistance value according to the intake air temperature. The lower the intake air temperature, the greater the thermistor resistance value. The higher the intake air temperature, the lower the thermistor resistance value (See Fig. 1).

The sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the sensor from terminal THIA via resistor R. Resistor R and the sensor are connected in series. When the resistance value of the sensor changes in accordance with changes in the IAT, the potential at terminal THIA also changes. Based on this signal, the ECM corrects the fuel injection volume to improve driveability with a cold engine.

P1495
DTC Detection Drive Pattern	DTC Detection Condition	Trouble Area
Ignition switch ON for 1 second	Open or short in the intake air temperature (IAT) sensor circuit for 0.5 seconds (1 trip detection logic).	Open or short in intake air temperature (IAT) sensor circuit IAT sensor ECM

P1496
DTC Detection Drive Pattern	DTC Detection Condition	Trouble Area
Ignition switch ON for 1 second	Short in the IAT sensor circuit for 0.5 seconds (1 trip detection logic).	Short in IAT sensor circuit IAT sensor ECM

P1497
DTC Detection Drive Pattern	DTC Detection Condition	Trouble Area
Ignition switch ON for 1 second	Open in the IAT sensor circuit for 0.5 seconds (1 trip detection logic).	Open in IAT sensor circuit IAT sensor ECM

Related Data List
DTC No.	Data List
P1495	Intake Air Temp (Turbo)
P1496
P1497

HINT:

If DTC P1495, P1496 and/or P1497 is stored, the following symptoms may appear:

Misfire

Combustion noise

Black smoke

White smoke

Lack of power

WIRING DIAGRAM

Dtc P1495 Intake Air Temperature Sensor 1 Circuit. 1VD-FTV ENGINE CONTROL. Land Cruiser URJ200 URJ202 GRJ200 VDJ200

INSPECTION PROCEDURE

NOTICE:

After replacing the ECM, the new ECM needs registration () and initialization ().

HINT:

If DTCs relating to different systems are stored, and they share terminal E2 as their ground, check this ground circuit first.

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, and other data from the time the malfunction occurred.

1.READ VALUE USING INTELLIGENT TESTER (INTAKE AIR TEMPERATURE [TURBO])

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON and turn the tester on.

Enter the following menus: Powertrain / Engine / Data List / Intake Air Temp (Turbo).

Read the value.

OK:
Same as air temperature near intake manifold.

Result
Result	Proceed to
-40°C (-40°F)	A
140°C (284°F) or higher	B
OK (same as air temperature near intake manifold)	C

HINT:

If there is an open circuit, the tester indicates -40°C (-40°F).

If there is a short circuit, the tester indicates 140°C (284°F) or more.

Go to step 4

Go to step 11

A

2.READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN WIRE HARNESS)

Disconnect the intake air temperature (IAT) sensor connector.

Connect terminals 1 and 2 of the IAT sensor wire harness side connector.

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON and turn the tester on.

Enter the following menus: Powertrain / Engine / Data List / Intake Air Temp (Turbo).

Read the value.

OK:
140°C (284°F) or higher

Go to step 7

Go to step 3

3.CHECK HARNESS AND CONNECTOR (INTAKE AIR TEMPERATURE SENSOR - ECM)

Disconnect the IAT sensor connector.

Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open):
for LHD
Tester Connection Condition Specified Condition
C79-2 - C45-74 (THIA) Always Below 1 Ω
C79-1 - C45-75 (E2) Always Below 1 Ω
for RHD
Tester Connection Condition Specified Condition
C79-2 - C46-74 (THIA) Always Below 1 Ω
C79-1 - C46-75 (E2) Always Below 1 Ω

for LHD
Tester Connection	Condition	Specified Condition
C79-2 - C45-74 (THIA)	Always	Below 1 Ω
C79-1 - C45-75 (E2)	Always	Below 1 Ω

for RHD
Tester Connection	Condition	Specified Condition
C79-2 - C46-74 (THIA)	Always	Below 1 Ω
C79-1 - C46-75 (E2)	Always	Below 1 Ω

Go to step 9

Go to step 8

4.READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS)

Disconnect the IAT sensor connector.

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON and turn the tester on.

Enter the following menus: Powertrain / Engine / Data List / Intake Air Temp (Turbo).

Read the value.

OK:
-40°C (-40°F)

Go to step 10

Go to step 5

5.CHECK HARNESS AND CONNECTOR (INTAKE AIR TEMPERATURE SENSOR - ECM)

Disconnect the IAT sensor connector.

Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Short):
for LHD
Tester Connection Condition Specified Condition
C79-2 or C45-74 (THIA) - Body ground Always 10 kΩ or higher
for RHD
Tester Connection Condition Specified Condition
C79-2 or C46-74 (THIA) - Body ground Always 10 kΩ or higher

for LHD
Tester Connection	Condition	Specified Condition
C79-2 or C45-74 (THIA) - Body ground	Always	10 kΩ or higher

for RHD
Tester Connection	Condition	Specified Condition
C79-2 or C46-74 (THIA) - Body ground	Always	10 kΩ or higher

Go to step 8

OK

6.REPLACE ECM

Replace the ECM ().

Go to step 11

7.CONFIRM GOOD CONNECTION TO SENSOR. IF OK, REPLACE INTAKE AIR TEMPERATURE SENSOR

Replace the intake air temperature sensor ().

Go to step 11

8.REPAIR OR REPLACE HARNESS OR CONNECTOR

Go to step 11

9.CONFIRM GOOD CONNECTION TO ECM. IF OK, REPLACE ECM.

Replace the ECM ().

Go to step 11

10.REPLACE INTAKE AIR TEMPERATURE SENSOR

Replace the intake air temperature sensor ().

NEXT

11.CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

Connect the intelligent tester to the DLC3.

Clear the DTCs ().

Turn the ignition switch off.

Turn the ignition switch to ON for 1 second.

Enter the following menus: Powertrain / Engine / DTC.

Confirm that the DTC is not output again.

END

1VD-FTV ENGINE CONTROL

Land Cruiser URJ200 URJ202 GRJ200 VDJ200

ECD SYSTEM w/o DPF