Toyota Tundra. Manual — part 1525

Fig. 70: Identifying Terminals Of D7 MAF And D74 ECM Meter Connectors
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

b. Disconnect the D74 ECM connector.

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

Standard resistance

RESISTANCE SPECIFIED CONDITION

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step.

7. CHECK HARNESS AND CONNECTOR (SENSOR GROUND)

a. Disconnect the D7 MAF meter connector.

Fig. 71: Identifying Terminals Of D7 MAF Meter Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

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

Tester Connection

Condition Specified Condition

D7-3 (VG) - D74-74 (VG)

Always

Below 1 ohms

D7-2 (E2G) - D74-75 (E2G)

Always

Below 1 ohms

D7-3 (VG) or D74-74 (VG) - Body ground Always

10 kohms or higher

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

Standard resistance

RESISTANCE SPECIFIED CONDITION

NG: REPLACE ECM (See REMOVAL )

OK: REPLACE MASS AIR FLOW METER (See REMOVAL )

DTC P0111 INTAKE AIR TEMPERATURE SENSOR 1 CIRCUIT RANGE/PERFORMANCE

DESCRIPTION

Tester Connection

Condition Specified Condition

D7-2 (E2G) - Body ground Always

Below 1 ohms

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

Fig. 72: Resistance And Temperature Graph
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

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 is low, the resistance of the thermistor increases. When the temperature is high, the resistance
drops. These variations in resistance are transmitted to the ECM as voltage changes (See Fig. 72).

The IAT sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R. Resistor R and
the (AT 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

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

injection volume when the engine is cold to improve driveability.

DTC DETECTION CONDITION AND TROUBLE AREA REFERENCE CHART

MONITOR DESCRIPTION

The ECM performs OBD II monitoring based on the values from the intake air temperature sensor. If there is no
change of the sensor value within the normal range, 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 engine is started (short soak
or long soak).

MONITOR STRATEGY

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

All:

TYPICAL ENABLING CONDITIONS - ALL

DTC

DTC Detection Condition

Trouble Area

P0111

When either condition below is
met:

1. The intake air temperature

change is small, from the
previous trip warm-up to the
following trip (2 trip
detection logic).

2. When the change in the

intake air temperature after
engine start is less than the
threshold value.

Mass air flow meter assembly

Related DTCs

P0111: Intake air temperature sensor rationality (After engine stop)
P0111: Intake air temperature sensor rationality (After cold engine
start)

Required Sensors/Components
(Main)

Intake Air Temperature (IAT) sensor

Required Sensors/Components (Sub) -
Frequency of Operation

Once per driving cycle

Duration

10 seconds or more

MIL Operation

2 driving cycles

Sequence of Operation

None

Monitor runs whenever following DTCs are not

P0102, P0103 (Mass Air Flow Sensor)
P0115, P0117, P0118 (Engine Coolant Temperature

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra