FI4741
(fig. 1)
Acceptable
Resistance k
Ω
- 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
Temp.
°
C (F
°
)
-
DIAGNOSTICS
ENGINE
DI-27
181
Author:
Date:
2001 SIENNA (RM787U)
DTC
P0110
Intake Air Temp. Circuit Malfunction
CIRCUIT DESCRIPTION
The intake air temp. sensor is built into the air flow meter 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. The 5 V power source voltage in the ECM is
applied to the intake air temperature sensor from the terminal THA via resistor R.
That is, the 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 injection vol-
ume to improve driveability during cold engine operation.
If the ECM detects the DTC P0110, it operates the fail-safe function in which the intake air temperature is
assumed to be 20
°
C (68
°
F).
<Reference>
Intake air temp.
°
C (
°
F)
Resistance
(k
Ω
)
Voltage
(V)
-20 (-4)
16.0
± 2.4
4.3
20 (68)
2.45
±
0.24
2.4
60 (140)
0.58
±
0.087
0.9
DTC No.
DTC Detecting Condition
Trouble Area
P0110
Open or short in intake air temp. sensor circuit
Open or short in intake air temp. sensor circuit
Intake air temp. sensor (built into mass air flow meter)
ECM
HINT:
After confirming DTC P0110, use the OBD II scan tool or TOYOTA hand-held tester to confirm the intake
air temp. from ”CURRENT DATA”.
Temp. Displayed
Malfunction
-40
°
C ( -40
°F
)
Open circuit
140
°
C ( 284
°F
) or more
Short circuit
DI21U-03
