Toyota Sequoia (2005). Manual - part 77

–

DIAGNOSTICS

ENGINE

DI–111

305

TYPICAL ENABLING CONDITIONS

It

Specification

Item

Minimum

Maximum

The monitor will run whenever this DTC is

not present

See page 

DI–18

High voltage:

Engine speed

–

2,000 rpm

MAF meter voltage

–

4.9 V

Engine coolant temperature

70



C (158



F)

–

Low voltage:

Engine speed

300 rpm

–

MAF meter voltage

0.2 V

–

Fuel cut

OFF

TYPICAL MALFUNCTION THRESHOLDS

Detection Criteria

Threshold

Mass air flow meter voltage (High voltage)

More than 2.2 V (varies with throttle position sensor voltage)

Mass air flow meter voltage (Low voltage)

Less than 1.0 V (varies with throttle position sensor voltage)

DI–112

–

DIAGNOSTICS

ENGINE

306

INSPECTION PROCEDURE

HINT:
Read freeze frame data using 

the hand−held tester

. Freeze frame data records the engine conditions when

a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was
running or stopped, if the engine was warmed up or not, if the air–fuel ratio was lean or rich, as well as other
data from the time when a malfunction occurred.

1

Are there any other codes (besides DTC P0101) being output?

PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Turn the ignition switch ON and push the hand–held tester main switch ON.

(c)

When using hand–held tester, enter the following menu: DIAGNOSIS/ENHANCED OBD II/DTC INFO/
CURRENT CODES.

CHECK:
Read the DTC using the hand–held tester.
RESULT:

Display (DTC output)

Proceed to

”P0101” and other DTCs

A

Only P0101

B

HINT:
If any other codes besides P0101 are output, perform the troubleshooting for those codes first.

B

Replace mass air flow meter.

A

Go to relevant DTC chart (See page 

DI–58

).

– 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

A21047

Acceptable

(Fig.1)

Resistance K

Ω

Temp. 



C (



F)

–

DIAGNOSTICS

ENGINE

DI–113

307

DTC

P0110

Intake Air Temperature Circuit

DTC

P0112

Intake Air Temperature Circuit Low Input

DTC

P0113

Intake Air Temperature Circuit High Input

CIRCUIT DESCRIPTION

The intake air temperature (IAT) sensor, mounted on the mass
air flow (MAF) meter, monitors the intake air temperature. The
IAT sensor has a thermistor that varies its resistance depending
on the temperature of the intake air. When the air temperature
is low, the resistance in the thermistor increases. When the tem-
perature is high, the resistance drops. The resistance varies as
voltage changes to the ECM terminal.
 (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
(THAR) 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 voltage at terminal THA (THAR) also
changes. Based on this signal, the ECM increases the fuel in-
jection volume to improve the driveability during cold engine op-
eration.

DTC No.

Proceed to

DTC Detection Condition

Trouble Area

P0110

Step 1

Open or short in intake air

temperature sensor circuit for

0.5 sec.

Open or short in intake air temperature sensor circuit

P0112

Step 4

Short in intake air tempera-

ture sensor circuit for 0.5 sec.

Open or short in intake air temperature sensor circuit

Intake air temperature sensor (built in mass air flow meter)

ECM

P0113

Step 2

Open in intake air tempera-

ture sensor circuit for 0.5 sec.

ECM

HINT:
After confirming DTC ”P0110, P0112 or P0113”, use the hand–held tester to confirm the intake air tempera-
ture in the ”DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL”.

Temperature Displayed

Malfunction

–40

°

C (–40

°F)

Open circuit

140

°

C (284

°F) or more

Short circuit

DI3HN–13

DI–114

–

DIAGNOSTICS

ENGINE

308

MONITOR DESCRIPTION

The ECM monitors the sensor voltage and uses this value to calculate the intake air temperature. When the
sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the IAT
(Intake Air Temperature) sensor and sets a DTC.
Example:
When the sensor voltage output is equal to –40



C (–40



F), or more than 140



C (284



F).

MONITOR STRATEGY

P0110

Intake air temperature sensor range check 
(Fluttering)

Related DTCs

P0112

Intake air temperature sensor range check 
(Low resistance)

P0113

Intake air temperature sensor range check 

(High resistance)

Required sensors/components

Intake air temperature sensor

Frequency of operation

Continuous

Duration

0.5 sec.

MIL operation

Immediate

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever these

DTCs are not present

See page 

DI–18

The typical enabling condition is not avail-

able

–

TYPICAL MALFUNCTION THRESHOLDS

Detection Criteria

Threshold

P0110:

Intake air temperature sensor resistance
(Intake air temperature)

Less than 98.5 

Ω,

 or more than 156 k

Ω

(More than 140



C (284



F), or less than –40



C (–40



F)

P0112:

Intake air temperature sensor resistance
(Intake air temperature)

Less than 98.5 

Ω

(More than 140



C (284



F))

P0113:

Intake air temperature sensor resistance
(Intake air temperature)

More than 156 k

Ω

(Less than –40



C (–40



F))

COMPONENT OPERATING RANGE

Parameter

Standard Value

Intake air temperature sensor resistance

98.5 

Ω 

(140



C (284



F)) to 156 k

Ω 

(–40



C (–40



F))