Toyota Tundra. Manual — part 1345

Fig. 74: Identifying D28 ECT Sensor & D74 ECM Connectors

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : REPLACE ECM (See REMOVAL )

DTC P0116 ENGINE COOLANT TEMPERATURE CIRCUIT RANGE/PERFORMANCE PROBLEM

DESCRIPTION

Refer to DTC P0115 .

DTC DETECTION CONDITION AND TROUBLE AREA

DTC

Code

DTC Detection Condition

Trouble Area

P0116

When either of following conditions met (2 trip detection logic):



When cold engine started and engine warmed up, Engine Coolant
Temperature (ECT) sensor value does not change.



After warmed up engine stopped and then next cold engine start
performed, ECT sensor value does not change.



Thermostat



ECT
sensor

2008 Toyota Tundra

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

MONITOR DESCRIPTION

Engine coolant temperature (ECT) sensor cold start monitor

When a cold engine start is performed and then the engine is warmed up, if the ECT sensor value does not
change, it is determined that a malfunction has occurred. If this is detected in 2 consecutive driving cycles, the
MIL is illuminated and a DTC is set.

ECT sensor soak monitor

If the ECT sensor value does not change after the warmed up engine is stopped and then the next cold engine
start is performed, it is determined that a malfunction has occurred. If this is detected in 2 consecutive driving
cycles, the MIL is illuminated and a DTC is set.

ECT sensor high side stuck monitor (only for Mexico models)

The ECM monitors the sensor voltage and uses this value to calculate the ECT. If the sensor voltage output
deviates from the normal operating range, the ECM interprets this deviation as a malfunction in the ECT sensor
and sets the DTC.

Examples:



Upon starting the engine, the ECT is between 35°C and 60°C (95°F and 140°F). If after driving for 250
seconds, the ECT remains within 3°C (5.4°F) of the starting temperature, the DTC is set (2 trip detection
logic).



Upon starting the engine, the ECT is over 60°C (140°F). If after driving for 250 seconds, the ECM
remains within 1°C (1.8°F) of the starting temperature, the DTC is set (6 trip detection logic).

MONITOR STRATEGY

MONITOR STRATEGY

P0116

For Mexico Models:
Case 1:
Engine Coolant Temperature (ECT) between 35°C and 60°C (95°F and 140°
F) when engine started, and conditions (a) and (b) met (2 trip detection logic)

a. Vehicle driven at varying speeds (accelerated and decelerated)

b. ECT remains within 3°C (5.4°F) of initial ECT Case 2:

ECT more than 60°C (140°F) when engine started, and conditions (a) and (b)
met (6 trip detection logic)

a. Vehicle driven at varying speeds (accelerated and decelerated)

b. ECT measurements remain within 1°C (1.8°F) of initial ECT on 6

successive occasions



Thermostat



ECT
sensor

2008 Toyota Tundra

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

TYPICAL ENABLING CONDITIONS

ECT sensor cold start monitor:

TYPICAL ENABLING CONDITIONS - ECT SENSOR COLD START MONITOR

ECT sensor soak monitor:

TYPICAL ENABLING CONDITIONS - ECT SENSOR SOAK MONITOR

TYPICAL MALFUNCTION THRESHOLDS

ECT sensor cold start monitor:

TYPICAL MALFUNCTION THRESHOLDS - ECT SENSOR COLD START MONITOR

Related DTCs

P0116: Engine coolant temperature (ECT) sensor cold start
monitor
P0116: ECT sensor soak monitor

Required Sensors/Components (Main) ECT sensor
Required Sensors/Components
(Related)

None

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 not present

P0102 - P0103: Mass Air Flow (MAF) meter
P0110 - P0113: Intake Air Temperature (IAT) sensor

Battery voltage

10.5 V or higher

Time after engine start

1 second or more

ECT at engine start

Less than 60°C (140°F)

IAT sensor circuit

OK

Soak time

0 seconds or more

Accumulated MAF

2161 g or more

Engine

Running

Fuel cut

OFF

Difference between ECT at engine start and IAT

Less than 40°C (72°F)

Monitor runs whenever following DTCs not present

P0102-P0103: MAF meter

Battery voltage

10.5 V or higher

Engine

Running

Soak time

5 hours or more

Either (a) or (b) condition met

-

(a) ECT

60°C (140°F) or more

(b) Accumulated MAF

4300 g or more

2008 Toyota Tundra

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

ECT sensor soak monitor:

TYPICAL MALFUNCTION THRESHOLDS - ECT SENSOR SOAK MONITOR

COMPONENT OPERATING RANGE

COMPONENT OPERATING RANGE

INSPECTION PROCEDURE

HINT:



If any of DTCs P0115, P0117, P0118 or P0125 are set simultaneously with DTC P0116, the ECT sensor
may have an open or a short circuit. Troubleshoot those DTCs first.



Read freeze frame data using the Techstream. Freeze frame data records the engine condition when
malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was
moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other
data from the time the malfunction occurred.

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0116)

a. Connect the Techstream to the DLC3.

b. Turn the ignition switch to ON.

c. Turn the Techstream ON.

d. Enter the following menus: Powertrain/Engine and ECT/Trouble Codes.

e. Read the DTC.

Result

RESULT REFERENCE

B : GO TO DTC CHART (See DIAGNOSTIC TROUBLE CODE CHART )

A : Go To Next Step

2. INSPECT THERMOSTAT

a. Remove the thermostat. (See REMOVAL ).

ECT sensor value change

Less than 5°C (9°F)

Difference between current ECT sensor value and previous ECT sensor value when
engine stopped

Less than 5°C (9°
F)

ECT

ECT sensor value changes in accordance with actual ECT

Result

Proceed To

P0116 is output

A

P0116 and other DTCs are output

B

2008 Toyota Tundra

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