Toyota Sequoia (2005). Manual — part 80
A19552
Engine Coolant
Temp. Sensor
2
1
THW
E2
ECM
E2
B17441
Engine Coolant
Temp. Sensor
ECM
E2
THW
E2
THW
E2
E8
ECM Connector
–
DIAGNOSTICS
ENGINE
DI–123
317
2
Check for open in harness or ECM.
PREPARATION:
(a)
Disconnect the E2 engine coolant temperature (ECT)
sensor connector.
(b)
Connect terminals 1 and 2 of the engine coolant tempera-
ture sensor wire harness side connector.
(c)
Turn the ignition switch ON.
(d)
When using hand–held tester, enter the following menu:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL /
COOLANT TEMP.
CHECK:
Read the temperature value on the hand–held tester.
OK:
Standard: Temperature value: 140
°
C (284
°
F) or more
OK
Confirm good connection at sensor. If OK, re-
place engine coolant temperature sensor.
NG
3
Check for open in harness or ECM.
PREPARATION:
(a)
Disconnect the E2 engine coolant temperature sensor
connector.
(b)
Connect terminals THW and E2 of the E8 ECM connector.
HINT:
Before checking, do a visual and contact pressure checks for
the ECM connector.
(c)
Turn the ignition switch ON.
(d)
When using hand–held tester, enter the following menu:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL /
COOLANT TEMP.
CHECK:
Read the temperature value on the OBD II scan tool or the
hand–held tester.
OK:
Standard: Temperature value: 140
°
C (284
°
F) or more
OK
Repair or replace harness or connector.
NG
A19550
Engine Coolant
Temp. Sensor
ECM
2
1
E2
THW
E2
B17442
ECM
Engine Coolant
Temp. Sensor
E2
THW
E2
ECM Connector
E8
DI–124
–
DIAGNOSTICS
ENGINE
318
Confirm good connection at ECM. If OK, re-
place ECM (See page
4
Check for short in harness and ECM.
PREPARATION:
(a)
Disconnect the E2 engine coolant temperature sensor
connector.
(b)
Turn the ignition switch ON.
(c)
When using hand–held tester, enter the following menu:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL /
COOLANT TEMP.
CHECK:
Read the temperature value on the hand–held tester.
OK:
Standard: Temperature value: –40
°
C (–40
°
F)
OK
Replace engine coolant temperature sensor.
NG
5
Check for short in harness or ECM.
PREPARATION:
(a)
Disconnect the E8 ECM connector.
(b)
Turn the ignition switch ON.
(c)
When using hand–held tester, enter the following menu:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL /
COOLANT TEMP.
CHECK:
Read the temperature value on the hand–held tester.
OK:
Standard: Temperature value: –40
°
C (–40
°
F)
OK
Repair or replace harness or connector.
NG
Replace ECM (See page
–
DIAGNOSTICS
ENGINE
DI–125
319
DTC
P0116
Engine Coolant Temperature Circuit Range/
Performance Problem
CIRCUIT DESCRIPTION
Refer to DTC P0115 on page
.
DTC No.
DTC Detecting Condition
Trouble Area
If the engine coolant temperature was 35
°
C (95
°
F) or more but
less than 60
°
C (140
°
F) when the engine is started, and if
conditions (a) and (b) are met:
(a) Vehicle has accelerated and decelerated.
(b) Engine coolant temperature remains within 3
°
C (5.4
°
F) of
the initial engine coolant temperature (2 trip detection logic)
P0116
If the engine coolant temperature is more than 60
°
C (140
°
F)
when the engine is started, and if conditions (a) and (b) are
met:
(a) Vehicle has accelerated and decelerated.
(b) If the engine coolant temperature sensor records a temper-
ature variation below 1
°
C (1.8
°
F) successively 6 times (6
trip detection logic)
Engine coolant temperature sensor
MONITOR DESCRIPTION
The ECT (Engine Coolant Temperature) sensor is used to monitor the engine coolant temperature. The ECT
sensor has a thermistor that varies its resistance depending on 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. The variations in resistance are reflected in the voltage output from the sensor. The ECM
monitors the sensor voltage and uses this value to calculate the engine coolant temperature. When the sen-
sor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the ECT
sensor and sets a DTC.
Examples:
(1) Upon starting the engine, the ECT is between 35
°
C (95
°
F) and 60
°
C (140
°
F). If after driving for 250 sec.,
the ECT still remains within 3
°
C (5.4
°
F) of the starting temperature, a DTC will be set (2 trip detection logic).
(2) Upon starting the engine, the ECT is over 60
°
C (140
°
F). If after driving for 250 sec., the ECT still remains
within 1
°
C (1.8
°
F) of the starting temperature, a DTC will be set (6 trip detection logic).
MONITOR STRATEGY
Related DTCs
P0116
Engine coolant temperature sensor range check
(Stuck)
Main sensors/components
Engine coolant temperature sensor
Required sensors/components
Related sensors/components
Intake air temperature sensor, Crankshaft
position sensor, Mass air flow meter
Frequency of operation
Continuous
Duration
250 sec.
MIL operation
2 driving cycles (When temperature is fixed between 35
C (95
F) and 60
C (140
F))
6 driving cycles (When temperature is fixed at 60
C (140
F) or more)
Sequence of operation
None
DI3HP–11
DI–126
–
DIAGNOSTICS
ENGINE
320
TYPICAL ENABLING CONDITIONS
It
Specification
Item
Minimum
Maximum
The monitor will run whenever this DTC is
not present
See page
Case 1 (When temperature is fixed between 35
C (95
F) and 60
C (140
F)):
Cumulative idle off period
250 sec.
–
Speed increase 30 km/h (18.6 mph) or
more
10 times
–
Engine coolant temperature
35
C (95
F)
60
C (140
F)
Intake air temperature
–6.7
C (20
F)
–
Case 2 (When temperature is fixed at 60
C (140
F) or more):
Engine coolant temperature at engine
start
60
C (140
F)
–
Intake air temperature
–6.7
C (20
F)
–
Stop and go
Once or more (Stop for 20 sec. or more and accelerate to more than 70 km/h (43.5 mph)
with in 40 sec.)
Steady driving and stop *
Once or more
*: Vehicle is driven by 65 km/h (40.4 mph) or more for 30 sec. or more and the vehicle speed reaches 70
km/h (43.5 mph). The vehicle is decelerated from 65 km/h (40.4 mph) to 3 km/h (1.86 mph) or less within
35 sec. and stopped for 10 sec.
TYPICAL MALFUNCTION THRESHOLDS
Detection Criteria
Threshold
Case1 (When temperature is fixed between 35
C (95
F) and 60
C (140
F)):
Change of engine coolant temperature value
Less than 3
C (5.4
F)
Case2 (When temperature is fixed at 60
C (140
F) or more):
Change of engine coolant temperature value
1
C (1.8
F) or less
COMPONENT OPERATING RANGE
Standard Value
Engine coolant temperature changes with the actual engine coolant temperature.
INSPECTION PROCEDURE
HINT:
If DTC P0115, P0116, P0117, P0118 and P0125 are output simultaneously, ECT sensor circuit may
be open or shorted. Perform the troubleshooting of DTC P0115, P0117 or P0118 first.
Read freeze frame data using
the hand−held tester
. Freeze frame data records the engine conditions
when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the
vehicle was running or stopped, if the engine was warmed up or not, if the air–fuel ratio was lean or
rich, as well as other data from the time when a malfunction occurred.
Replace engine coolant temperature sensor.
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