Page 2177 of 4592

A09428
(Fig.1)
Acceptable
Resistance kW
± 20 0 20 40 60 80 100
(± 4) (32) (68) (104) (140) (176) (212) 30
20
10
5
3
2
1
0.5
0.3
0.2
0.1
Te m p .°C (F°)
DI±26
± DIAGNOSTICSENGINE
DTC P0110 Intake Air Temp. Circuit Malfunction
CIRCUIT DESCRIPTION
The intake air temperature sensor is built into the air cleaner
cap and senses the intake air temperature.
A thermistor built in the sensor changes the resistance value
according to the intake air temperature, the lower the intake air
temperature, the greater the thermistor resistance value, and
the higher the intake air temperature, the lower the thermistor
resistance value (See Fig.1).
The intake air temperature sensor is connected to the ECM
(See below). The 5 V power source voltage in the ECM is ap-
plied to the intake air temperature sensor from terminal THA via
a resistor R.
That is, 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 also
changes. Based on this signal, the ECM increases the fuel in-
jection volume to improve driveability during cold engine opera-
tion.
If the ECM detects the DTC P0110, it operates the fail safe func-
tion in which the intake air temperature is assumed to be 20°C
(68°F).
DTC No.DTC Detecting ConditionTrouble Area
P0110Open or short in intake air temp. sensor circuit
Open or short in intake air temp. sensor circuit
Intake air temp. sensor
ECM
HINT:
After confirming DTC P0110, use the OBD II scan tool or TOYOTA hand±held tester to confirm the intake
air temperature from the CURRENT DATA.
Temperature DisplayedMalfunction
±40°C (±40°F)Open circuit
140°C (284°F) or moreShort circuit
DI00O±07
Page 2178 of 4592

A00310
Intake Air Temp. Sensor
E5
E53
9ECM
5 V
THA
E2
E1 R
Y±B
BR 2
1
± DIAGNOSTICSENGINE
DI±27
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
If DTCs P0105, P0106, P0110, P0115, P0120, P0180 and P0190 are output simultaneously, E2 (sen-
sor ground) may be open.
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame
records the engine conditions when the malfunction is detected. When troubleshooting it is useful for
determining whether the vehicle was running or stopped, the engine was warmed up or not, the air±fuel
ratio was lean or rich, etc. at the time of the malfunction.
1 Connect OBD II scan tool or TOYOTA hand±held tester, and read value of intake
air temperature.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(b) Turn the ignition switch ON and push the OBD II scan tool or TOYOTA hand±held tester main switch
ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYOTA hand±held tester.
OK:
Same as actual air intake temperature.
HINT:
If there is open circuit, OBD II scan tool or TOYOTA hand±held tester indicates ±40°C (±40°F).
If there is short circuit, OBD II scan tool or TOYOTA hand-held tester indicates 140°C (284°F) or more.
NG ±40°C (±40°F) .... Go to step 2.
140°C (284°F) or more .... Go to step 4.
OK
Check for intermittent problems (See page
DI±3).
Page 2179 of 4592

A00391
ECM
13
2
9 Intake Air Temp.
Sensor
E55 V
E5THA
E2
E1
ON
A03010A09256
Intake Air Temp.
SensorECM
3
9
E5 E5THA
E25 V
ON
E1
THAE2
DI±28
± DIAGNOSTICSENGINE
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the intake air temperature sensor connector.
(b) Connect the sensor wire harness terminals together.
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand±held tester.
OK:
Temp. value: 140°C (284°F) or more
OK Confirm good connection at sensor. If OK, re-
place intake air temperature sensor.
NG
3 Check for open in harness or ECM.
PREPARATION:
(a) Remove the glove compartment (See Pub. No. RM654U,
page SF±64).
(b) Connect between terminals THA and E2 of the ECM con-
nector.
HINT:
The intake air temperature sensor connector is disconnected.
Before checking, do a visual and contact pressure check for the
ECM connector (See page IN±29).
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand±held tester.
OK:
Temperature value: 140°C (284°F) or more
OK Open in harness between terminals E2 or THA,
repair or replace harness.
NG
Confirm good connection at ECM. If OK,
check and replace ECM (See page IN±29).
Page 2180 of 4592
A00393
ON
Intake Air Temp.
Sensor
2
1ECM
3
9
THA
E2
E15 V
E5
E5
A03011A09257
Intake Air Temp.
SensorECM
THA
E25 V
E1
ON
E5 Connector
± DIAGNOSTICSENGINE
DI±29
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the intake air temperature sensor connector.
(b) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand±held tester.
OK:
Temperature value: ±40°C (±40°F)
OK Replace intake air temperature sensor.
NG
5 Check for short in harness or ECM.
PREPARATION:
(a) Remove the glove compartment (See Pub. No. RM654U,
page SF±64).
(b) Disconnect the E5 connector from the ECM.
HINT:
The intake air temperature sensor connector is disconnected.
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand±held tester.
OK:
Temperature value: ±40°C (±40°F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See page IN±29).
Page 2181 of 4592

A00310
Engine Coolant Temp.
Sensor
2
1ECM
G±B
BR4
E5
E595 V
THW
E2
E1 R DI±30
± DIAGNOSTICSENGINE
DTC P0115 Engine Coolant Temp. Circuit Malfunction
CIRCUIT DESCRIPTION
A thermistor built into the engine coolant temperature sensor changes the resistance value according to the
engine coolant temperature.
The structure of the sensor and connection to the ECM is the same as in the intake air temperature circuit
malfunction shown on page DI±26.
If the ECM detects the DTC P0115, it operates fail safe function in which the engine coolant temperature
is assumed to be 80°C (176°F).
DTC No.Detection ItemTrouble Area
P0115Open or short in engine coolant temp. sensor circuit
Open or short in engine coolant temp. sensor circuit
Engine coolant temp. sensor
ECM
HINT:
After confirming DTC P0115, use the OBD II scan tool or TOYOTA hand±held tester to confirm the engine
coolant temp. from the CURRENT DATA.
Temp. DisplayedMalfunction
±40°C (±40°F)Open circuit
140°C (284°F) or moreShort circuit
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
If DTCs P0105, P0106, P0110, P0115, P0120, P0180 and P0190 are output simultaneously, E2 (sen-
sor ground) may be open.
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame
records the engine conditions when the malfunction is detected. When troubleshooting it is useful for
determining whether the vehicle was running or stopped, the engine was warmed up or not, the air±fuel
ratio was lean or rich, etc. at the time of the malfunction.
DI00P±07
Page 2182 of 4592

A00395
ECM ON
Engine Coolant
Temp. Sensor
2
14
9
THW
E25 V
E1 E5
E5
± DIAGNOSTICSENGINE
DI±31
1 Connect OBD II scan tool or TOYOTA hand±held tester, and read value of engine
coolant temperature.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(b) Turn the ignition switch ON and push the OBD II scan tool or TOYOTA hand±held tester main switch
ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYOTA hand±held tester.
OK:
Same as actual engine coolant temperature.
HINT:
If there is open circuit, OBD II scan tool or TOYOTA hand±held tester indicates ±40°C (±40°F).
If there is open circuit, OBD II scan tool or TOYOTA hand-held tester indicates 140°C (284°F) or more.
NG ±40°C (±40°F) ... Go to step 2.
140°C (284°F) or more ... Go to step 4.
OK
Check for intermittent problems (See page
DI±3).
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the engine coolant temperature sensor con-
nector.
(b) Connect the sensor wire harness terminals together.
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand±held tester.
OK:
Temperature value: 140°C (284°F) or more
OK Confirm good connection at sensor. If OK, re-
place engine coolant temperature sensor.
NG
Page 2183 of 4592

A03012A09258
ON
Engine Coolant
Temp. SensorECM
THW
E2
4
2
15 V
THW
E1 E5
E5
9E2
A00397
ON
Engine Coolant
Temp. Sensor
4
9ECM
E5
E5THW
E25 V
E1
DI±32
± DIAGNOSTICSENGINE
3 Check for open in harness or ECM.
PREPARATION:
(a) Remove the glove compartment (See Pub. No. RM654U,
page SF±64).
(b) Connect between terminals THW and E2 of the ECM con-
nector.
HINT:
The engine coolant temperature sensor connector is discon-
nected. Before checking, do a visual and contact pressure
check for the ECM connector (See page IN±29).
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand±held tester.
OK:
Temperature value: 140°C (284°F) or more
OK Open in harness between terminals E2 or THW,
repair or replace harness.
NG
Confirm good connection at ECM. If OK,
check and replace ECM (See page IN±29).
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the engine coolant temperature sensor con-
nector.
(b) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand±held tester.
OK:
Temperature value: ± 40°C (± 40°F)
OK Replace engine coolant temperature sensor.
NG
Page 2184 of 4592
A03011A09257
Engine Coolant
Temp. Sensor
THW
E25 V
E1
ON
E5 Connector
± DIAGNOSTICSENGINE
DI±33
5 Check for short in harness or ECM.
PREPARATION:
(a) Remove the glove compartment (See Pub. No. RM654U,
page SF±64).
(b) Disconnect the E5 connector from the ECM.
HINT:
The engine coolant temp. sensor connector is disconnected.
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand±held tester.
OK:
Temperature value: ±40°C (±40°F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See page IN±29).