Toyota Tundra. Manual — part 1528

NG: Go to step 5

OK: REPLACE MASS AIR FLOW METER (See REMOVAL )

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

a. Disconnect the D7 MAF meter connector.

2009 Toyota Tundra

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

Fig. 78: 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.

2009 Toyota Tundra

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

Standard resistance

RESISTANCE SPECIFIED CONDITION

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: REPLACE ECM (See REMOVAL )

DTC P0115 ENGINE COOLANT TEMPERATURE CIRCUIT MALFUNCTION; DTC P0117 ENGINE
COOLANT TEMPERATURE CIRCUIT LOW INPUT; DTC P0118 ENGINE COOLANT
TEMPERATURE CIRCUIT HIGH INPUT

DESCRIPTION

A thermistor, whose resistance value varies according to the ECT, is built into the Engine Coolant Temperature
(ECT) sensor.

The structure of the sensor and its connection to the ECM are the same as those of the Intake Air Temperature
(IAT) sensor.

HINT:

When any of DTCs P0115, P0117 and P0118 are set, the ECM enters fail-safe mode. During fail-safe mode, the
ECT is estimated to be 80°C (176°F) by the ECM. Fail-safe mode continues until a pass condition is detected.

DTC DETECTION CONDITION AND TROUBLE AREA REFERENCE CHART

HINT:

When any of these DTCs are set, check the ECT by entering the following menus: Powertrain/Engine and
ECT/Data List/All Data/Coolant Temp.

Tester Connection

Condition Specified Condition

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

10 kohms or higher

DTC

DTC Detection Condition

Trouble Area

P0115

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



Open or short in ECT sensor
circuit



ECT sensor



ECM

P0117

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



Short in ECT sensor



ECT sensor



ECM

P0118

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



Open in ECT sensor circuit



ECT sensor



ECM

2009 Toyota Tundra

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

DATA LIST REFERENCE

MONITOR DESCRIPTION

The Engine Coolant Temperature (ECT) sensor is used to monitor the ECT. The ECT sensor has a thermistor
with a resistance that varies according to the temperature of the engine coolant. When the coolant temperature is
low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. These
variations in resistance are reflected in the output voltage from the sensor. The ECM monitors the sensor
voltage and uses this value to calculate the ECT. When the sensor output voltage deviates from the normal
operating range, the ECM interprets this as a fault in the ECT sensor and stores a DTC.

Example:

If the sensor output voltage is more than 4.91 V for 0.5 seconds or more, the ECM determines that there is an
open in the ECT sensor circuit, and stores DTC P0118. Conversely, if the voltage output is less than 0.14 V for
0.5 seconds or more, the ECM determines that there is a short in the sensor circuit, and stores DTC P0117.

If the malfunction is not repaired successfully, a DTC is stored 0.5 seconds after the engine is next started.

MONITOR STRATEGY

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

P0115:

TYPICAL MALFUNCTION THRESHOLDS - P0115

Temperature Displayed

Malfunction

-40°C (-40°F)

Open circuit

140°C (284°F) or higher

Short circuit

Related DTCs

P0115: ECT sensor range check (Fluctuating)
P0117: ECT sensor range check (Low voltage)
P0118: ECT sensor range check (High voltage)

Required Sensors/Components (Main)

ECT sensor

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

0.5 seconds

MIL Operation

Immediate

Sequence of Operation

None

Monitor runs whenever following DTCs not present

None

2009 Toyota Tundra

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