Toyota Tundra. Manual — part 1342

Fig. 66: Identifying D7 MAF Meter & D74 ECM Connectors

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : CONFIRM GOOD CONNECTION TO ECM. IF OK, REPLACE ECM (See REMOVAL )

5. READ VALUE USING TECHSTREAM (CHECK FOR SHORT IN WIRE HARNESS)

a. Disconnect the D7 MAF meter connector.

b. Connect the Techstream to the DLC3.

c. Turn the ignition switch to ON.

d. Turn the Techstream ON.

e. Enter the following menus: Powertrain/Engine and ECT/All Data/Intake Air.

f. Read the value displayed on the Techstream.

Standard value:

-40°C (-40°F)

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Fig. 67: D7 MAF Meter & ECM Circuit Diagram

NG : Go to step 6

OK : REPLACE MASS AIR FLOW METER (See REMOVAL )

6. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

a. Disconnect the D7 MAF meter connector.

b. Disconnect the D74 ECM connector.

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

Standard resistance

STANDARD RESISTANCE SPECIFICATION

Fig. 68: Identifying D7 MAF Meter & D74 ECM Connectors

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : REPLACE ECM (See REMOVAL )

DTC P0111 INTAKE AIR TEMPERATURE SENSOR GRADIENT TOO HIGH

DESCRIPTION

Tester Connection

Condition Specified Condition

D7-4 (THA) or D74-73 (THA) - Body ground Always

10 kohms or higher

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Fig. 69: Intake Air Temperature Graph

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. 69).

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

Resistor R and the IAT 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 injection volume when the engine is cold to improve driveability.

DTC DETECTION CONDITION AND TROUBLE AREA

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

DTC

Code

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

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

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

After engine stop:

TYPICAL ENABLING CONDITIONS - AFTER ENGINE STOP

After cold engine start:

TYPICAL ENABLING CONDITIONS - AFTER COLD ENGINE START

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

5 hours or more

MIL Operation

2 driving cycles

Sequence of Operation

None

Monitor runs whenever following DTCs are not present

None

Time after engine start

10 seconds or more

Battery voltage

10.5 V or higher

ECT sensor circuit

OK

ECT change since engine stop

-40°C (-40°F) or more

ECT before engine stop

70°C (158°F) or more

Accumulated MAF amount before engine stop

2300 g or more

Key-off duration

30 minutes

Key-off duration

5 hours

Time after engine start

10 seconds or more

ECT sensor circuit

OK

ECT

70°C (158°F) or more

Accumulated MAF amount

2300 g or more

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra