Toyota Tundra. Manual — part 1340

STANDARD RESISTANCE SPECIFICATION

Fig. 60: Identifying Mass Air Flow Meter & Integration Relay Connector Terminal

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : CHECK ECM POWER SOURCE CIRCUIT (See ECM POWER SOURCE CIRCUIT )

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

Tester Connection

Condition Specified Condition

D7-1 (+B) - 1B-4

Always

Below 1 ohms

D7-1 (+B) or 1B-4-Body ground Always

10 kohms or higher

Tester Connection

Condition Specified Condition

2008 Toyota Tundra

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

Fig. 61: Identifying D7 MAF Meter & D7 MAF Meter Connectors

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.

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

Standard resistance

STANDARD RESISTANCE SPECIFICATION

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

Tester Connection

Condition Specified Condition

D7-2 (E2G) - Body ground Always

Below 1 ohms

2008 Toyota Tundra

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

Fig. 62: Identifying D7 MAF Meter Connector

NG : REPLACE ECM (See REMOVAL )

OK : REPLACE MASS AIR FLOW METER (See REMOVAL )

DTC P0110 INTAKE AIR TEMPERATURE CIRCUIT MALFUNCTION; DTC P0112 INTAKE AIR
TEMPERATURE CIRCUIT LOW INPUT; DTC P0113 INTAKE AIR TEMPERATURE CIRCUIT
HIGH INPUT

DESCRIPTION

Fig. 63: Intake Air Temperature Graph

2008 Toyota Tundra

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

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. 63).

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.

HINT:

When any of DTCs P0110, P0112 and P0113 are set, the ECM enters fail-safe mode. During fail-safe mode, the
IAT is estimated to be 20°C (68°F) by the ECM. Fail-safe mode continues until a pass condition is detected.

DTC DETECTION CONDITION AND TROUBLE AREA

HINT:

When any of these DTCs are set, check the IAT by entering the following menus: Powertrain/Engine and
ECT/All Data/Intake Air.

TEMPERATURE SPECIFICATION

MONITOR DESCRIPTION

DTC

Code

DTC Detection Condition

Trouble Area

P0110

Open or short in IAT sensor circuit for 0.5 seconds (1 trip
detection logic)



Open or short in IAT sensor
circuit



IAT sensor (built into MAF
meter)



ECM

P0112

Short in IAT sensor circuit for 0.5 seconds (1 trip detection
logic)



Short in IAT sensor circuit



IAT sensor (built into MAF
meter)



ECM

P0113

Open in IAT sensor circuit for 0.5 seconds (1 trip detection
logic)



Open in IAT sensor circuit



IAT sensor (built into MAF
meter)



ECM

Temperature Displayed

Malfunction

-40°C (-40°F)

Open circuit

140°C (284°F) or higher

Short circuit

2008 Toyota Tundra

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