TOYOTA SEQUOIA 2001 Service Repair Manual

A19549
THA
E2ECM
2
1
Mass Air
Flow Meter Mass Air
Flow Meter
45
M1
THA E2
M1
B17441THA
E2
THA
E2ECM Mass Air Flow Meter
M1
E8
± DIAGNOSTICSENGINE
DI±117
311 Author: Date:
2005 SEQUOIA (RM1146U)
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the M1 mass air flow meter connector.
(b) Connect terminals 4 and 5 of the mass air flow meter 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 / IN-
TAKE AIR.
CHECK:
Read the temperature value on the hand±held tester.
OK:
Standard: Temperature value: 1405C (2845F) or more
OK Confirm good connection at sensor. If OK, re-
place mass air flow meter.
NG
3 Check for open in harness or ECM.
PREPARATION:
(a) Connect terminals THA and E2 of the E8 ECM connector.
HINT:
Before checking, do a visual and contact pressure check for the
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 / IN-
TAKE AIR.
CHECK:
Read the temperature value on the hand±held tester.
OK:
Standard: Temperature value: 1405C (2845F) or more
OK Repair or replace harness or connector.
NG
Confirm good connection at ECM. If OK, re-
place ECM (See page SF±80).

A19550
THA
E2ECM Mass Air Flow
Meter
M1
B17442
ECM Mass Air Flow Meter
THA
E2 M1
E8
DI±118
± DIAGNOSTICSENGINE
312 Author: Date:
2005 SEQUOIA (RM1146U)
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the M1 mass air flow meter connector.
(b) Turn the ignition switch ON.
(c) When using hand±held tester, enter the following menu:
DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / IN-
TAKE AIR.
CHECK:
Read the temperature value on the hand±held tester.
OK:
Standard: Temperature value: ±405C (±405F)
OK Replace mass air flow meter.
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 / IN-
TAKE AIR.
CHECK:
Read the temperature value on the hand±held tester.
OK:
Standard: Temperature value: ±405C (±405F)
OK Repair or replace harness or connector.
NG
Replace ECM (See page SF±80).

± DIAGNOSTICSENGINE
DI±119
313 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0115 Engine Coolant Temperature Circuit
DTC P0117 Engine Coolant Temperature Circuit Low
Input
DTC P0118 Engine Coolant Temperature Circuit High
Input
CIRCUIT DESCRIPTION
A thermistor is built in the Engine Coolant Temperature (ECT) sensor and changes the resistance value ac-
cording to the engine coolant temperature.
The structure of the sensor and connection to the ECM is the same as the Intake Air Temperature (IAT) sen-
sor.
HINT:
If the ECM detects the DTC ºP0115, P0117 or P0118º, it operates the fail±safe function in which the ECT
is assumed to be 80C (176F).
DTC No.Proceed toDTC Detection ConditionTrouble Area
P0115Step 1
Open or short in engine cool-
ant temperature sensor circuit
for 0.5 sec.
P0117Step 4
Short in engine coolant tem-
perature sensor circuit for 0.5
sec.
Open or short in engine coolant temperature sensor circuit

Engine coolant temperature sensor

ECM
P0118Step 2
Open in engine coolant tem-
perature sensor circuit for 0.5
sec.
HINT:
After confirming DTC ºP0115, P0117 or P0118º, use the OBD II scan tool or the hand±held tester to confirm
the engine coolant temperature from the DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL.
Displayed TemperatureMalfunction
±40°C (±40°F)Open circuit
140°C (284°F) or moreShort circuit
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 resistance varies as output voltage from the sensor changes.
The ECM monitors the sensor voltage and uses this value to calculate the engine coolant temperature.
When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault
in the ECT sensor and sets a DTC.
DI3HO±13

DI±120
± DIAGNOSTICSENGINE
314 Author: Date:
2005 SEQUOIA (RM1146U)
Example:
When the ECM calculates that the ECT is less than ±40C (±40F), or more than 140C (284F), and if either
the condition continues for 0.5 sec. or more, the ECM will set a DTC.
MONITOR STRATEGY
P0115Engine coolant temperature sensor range check
(Fluttering)
Related DTCsP0117Engine coolant temperature sensor range check
(Low resistance)
P0118Engine coolant temperature sensor range check
(High resistance)
Required sensors/componentsEngine coolant temperature sensor
Frequency of operationContinuous
Duration0.5 sec.
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
The monitor will run whenever these
DTCs are not presentSee page DI±18
The typical enabling condition is not avail-
able±
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
P0115:
Engine coolant temperature sensor resistance
(Coolant temperature)Less than 79 W, or more than 156 kW
(More than 140C (284F), or less than ±40C (±40F))
P0117:
Engine coolant temperature sensor resistance
(Coolant temperature)Less than 79 W
(More than 140C (284F))
P0118:
Engine coolant temperature sensor resistance
(Coolant temperature)More than 156 kW
(Less than ±40C (±40F))
COMPONENT OPERATING RANGE
ParameterStandard Value
Engine coolant temperature sensor resistance79 W (140C (284F)) to 156 kW (±40C (±40F))

FI6448
ECM
5 V
THW E2
Engine Coolant Temp. Sensor
2
1G±Y
G±W
E1 E2
E8
E8
2821
± DIAGNOSTICSENGINE
DI±121
315 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

If DTCs related to different system that have terminal E2 as the ground terminal are output simulta-
neously, terminal E2 may have an open circuit.

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.

DI±122
± DIAGNOSTICSENGINE
316 Author: Date:
2005 SEQUOIA (RM1146U)
1 Connect hand±held tester, and read value of engine coolant temperature.
PREPARATION:
(a) Connect the hand±held tester to the DLC3.
(b) Turn the ignition switch ON and push the hand±held tester main 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 the hand±held tester.
OK:
Same value as actual engine coolant temperature.
RESULT:
Displayed TemperatureProceed to
±40°C (±40°F)A
140°C (284°F) or moreB
OK (Same as present temperature)C
HINT:

If there is an open circuit, hand±held tester indicates ±40°C (±40°F).

If there is a short circuit, hand±held tester indicates 140°C (284°F) or more.
B Go to step 4.
C Check for intermittent problems
(See page DI±11).
A

A19552
Engine Coolant
Temp. Sensor
2
1THW
E2ECM
E2
B17441
Engine Coolant
Temp. Sensor
ECM
E2 THW
E2
THW
E2
E8ECM Connector
± DIAGNOSTICSENGINE
DI±123
317 Author: Date:
2005 SEQUOIA (RM1146U)
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: 1405C (2845F) 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: 1405C (2845F) 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
± DIAGNOSTICSENGINE
318 Author: Date:
2005 SEQUOIA (RM1146U)
Confirm good connection at ECM. If OK, re-
place ECM (See page SF±80).
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: ±405C (±405F)
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: ±405C (±405F)
OK Repair or replace harness or connector.
NG
Replace ECM (See page SF±80).

± DIAGNOSTICSENGINE
DI±125
319 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0116 Engine Coolant Temperature Circuit Range/
Performance Problem
CIRCUIT DESCRIPTION
Refer to DTC P0115 on page DI-119.
DTC No.DTC Detecting ConditionTrouble 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)
P0116If 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 DTCsP0116Engine coolant temperature sensor range check
(Stuck)
Main sensors/componentsEngine coolant temperature sensor
Required sensors/componentsRelated sensors/componentsIntake air temperature sensor, Crankshaft
position sensor, Mass air flow meter
Frequency of operationContinuous
Duration250 sec.
MIL operation2 driving cycles (When temperature is fixed between 35C (95F) and 60C (140F))
6 driving cycles (When temperature is fixed at 60C (140F) or more)
Sequence of operationNone
DI3HP±11

DI±126
± DIAGNOSTICSENGINE
320 Author: Date:
2005 SEQUOIA (RM1146U)
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
Case 1 (When temperature is fixed between 35C (95F) and 60C (140F)):
Cumulative idle off period250 sec.±
Speed increase 30 km/h (18.6 mph) or
more10 times±
Engine coolant temperature35C (95F)60C (140F)
Intake air temperature±6.7C (20F)±
Case 2 (When temperature is fixed at 60C (140F) or more):
Engine coolant temperature at engine
start60C (140F)±
Intake air temperature±6.7C (20F)±
Stop and goOnce 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 CriteriaThreshold
Case1 (When temperature is fixed between 35C (95F) and 60C (140F)):
Change of engine coolant temperature valueLess than 3C (5.4F)
Case2 (When temperature is fixed at 60C (140F) or more):
Change of engine coolant temperature value1C (1.8F) 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.