2001 TOYOTA SEQUOIA Service Repair Manual

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Page 329 of 4323

TOYOTA SEQUOIA 2001 Service Repair Manual B17411
E2 VC
E8ECM Connector
± DIAGNOSTICSENGINE
DI±135
329 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check voltage between terminals VC and E2 of ECM connector.
PREPARATION:
(a) Disconnect the T1

Page 330 of 4323

TOYOTA SEQUOIA 2001 Service Repair Manual DI±136
± DIAGNOSTICSENGINE
330 Author: Date:
2005 SEQUOIA (RM1146U)
Replace ECM (See page SF±80).

Page 331 of 4323

TOYOTA SEQUOIA 2001 Service Repair Manual ± DIAGNOSTICSENGINE
DI±137
331 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0121 Throttle/Pedal Position Sensor/Switch ºAº
Circuit Range/Performance Problem
HINT:
This is the purpose of the ºthr

± DIAGNOSTICSENGINE
DI±137
331 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0121 Throttle/Pedal Position Sensor/Switch ºAº
Circuit Range/Performance Problem
HINT:
This is the purpose of the ºthrottle position sensorº.
CIRCUIT DESCRIPTION
Refer to DTC P0120 on page DI±127.
DTC No.DTC Detecting ConditionTrouble Area
P0121
Condition (a) continues for 2.0 sec.:
(a) Difference between VTA1 and VTA2 deviates from the
threshold
Throttle control motor and sensor
MONITOR DESCRIPTION
The ECM uses throttle position sensor to monitor the throttle valve opening angle.
This sensor includes two signals, VTA1 and VTA2. VTA1 is used to detect the throttle opening angle and
VTA2 is used to detect malfunctions in VTA1. There are several checks that the ECM performs confirm prop-
er operation of the throttle position sensor and VTA1.
There is a specific voltage difference expected between VTA1 and VTA2 for each throttle opening angle.
If the voltage output difference of the VTA1 and VTA2 deviates from the normal operating range, the ECM
interprets this as a malfunction of the throttle position sensor. The ECM will turn on the MIL and a DTC is
set.
FAIL SAFE
If the ETCS (Electronic Throttle Control System) has a malfunction, the ECM cuts off current to the throttle
control motor. The throttle control valve returns to a predetermined opening angle (approximately 16°) by
the force of the return spring. The ECM then adjusts the engine output by controlling the fuel infection (inter-
mittent fuel±cut) and ignition timing in accordance with the accelerator pedal opening angle to enable the
vehicle to continue at a minimum speed.
If the accelerator pedal is depressed firmly and slowly, the vehicle can be driven slowly.
If a ºpassº condition is detected and then the ignition switch is turned OFF, the fail±safe operation will stop
and the system will return to normal condition.
MONITOR STRATEGY
Related DTCsP0121Throttle position sensor rationality
Required sensors/componentsThrottle position sensor
Frequency of operationContinuous
Duration2 sec.
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
VTA2 voltage±4.6 V
DI3HR±14

Page 332 of 4323

TOYOTA SEQUOIA 2001 Service Repair Manual DI±138
± DIAGNOSTICSENGINE
332 Author: Date:
2005 SEQUOIA (RM1146U)
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Different between VTA1 and VTA2
|VTA1 ± (VTA2 y 0.8 to 1.2)|*
* C

Page 333 of 4323

TOYOTA SEQUOIA 2001 Service Repair Manual ± DIAGNOSTICSENGINE
DI±139
333 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0125 Insufficient Coolant Temperature
for Closed Loop Fuel Control
CIRCUIT DESCRIPTION
Refer to DTC P0115 on page DI±11

± DIAGNOSTICSENGINE
DI±139
333 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0125 Insufficient Coolant Temperature
for Closed Loop Fuel Control
CIRCUIT DESCRIPTION
Refer to DTC P0115 on page DI±119.
DTC No.DTC Detection ConditionTrouble Area
If THW or THA is less than ±19.45°C (±3°F) at engine start
and 20 min. or more after starting engine, engine coolant
temp. sensor value is 20°C (68°F) or less (2 trip detection
logic)
P0125
If THW and THA is between ±19.45°C (±3°F) and ±8.34°C
(17°F) at engine start, 5 min. or more after starting engine
and engine coolant temp. sensor value is 20°C (68°F) or
less (2 trip detection logic)Cooling system
Engine coolant temperature sensor
Thermostat
If THW and THA greater than ±8.34°C (17°F) at engine
start and 2 min. or more after starting engine, engine cool-
ant temp. sensor value is 20°C (68°F) or less (2 trip detec-
tion logic)
MONITOR DESCRIPTION
The ECT (Engine Coolant Temperature) sensor is used to monitor the temperature of the engine coolant.
The resistance of the sensor varies with the actual coolant temperature. The ECM applies a voltage to the
sensor and the varying resistance of the sensor cause the signal voltage to vary. The ECM monitors the ECT
signal voltage after engine start±up.
If, after sufficient time has passed, the sensor still reports that the engine
is not warmed up enough for closed±loop fuel control after sufficient time has passed, the ECM interprets
this as a fault in the sensor or cooling system and sets a DTC.
Example:
The engine coolant temperature was 0C (32F) at engine start. After 5 min. running time, the ECT sensor
still indicates that the engine is not warmed up enough to begin air fuel ratio feedback control of the air±fuel
ratio. The ECM interprets this as a fault in the sensor or cooling system and will set a DTC.
MONITOR STRATEGY
Related DTCsP0125Insufficient coolant temperature for closed loop
fuel control
Required sensors/componentsMain sensors/componentsEngine coolant temperature sensor, Cooling sys-
tem, Thermostat
Required sensors/com onents
Related sensors/componentsMass air flow meter
Frequency of operationContinuous
2 min. (at engine start, engine coolant or intake air temperature of ±8.34°C (17°F) or more)
Duration
2 min. (at engine start, engine coolant or intake air tem erature of ±8.34C (17F) or more)
5 min. (at engine start, engine coolant or intake air temperature of ±19.45 to ±8.34°C (±3 to 17°F))Duration5 min. (at engine start, engine coolant or intake air tem erature of 19.45 to 8.34C (3 to 17F))
20 min. (at engine start, engine coolant or intake air temperature of less than ±19.45°C (±3°F))
MIL operation2 driving cycles
Sequence of operationNone
DICEP±02

Page 334 of 4323

TOYOTA SEQUOIA 2001 Service Repair Manual DI±140
± DIAGNOSTICSENGINE
334 Author: Date:
2005 SEQUOIA (RM1146U)
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI

DI±140
± DIAGNOSTICSENGINE
334 Author: Date:
2005 SEQUOIA (RM1146U)
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
Fuel cutOFF
EngineRunning
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
Time until ºengine coolant temperatureº detection temperature reaches feedback start temperature
When the temperature at the time of engine starting is
±8.34°C (17°F) or moreEngine coolant temperature is less than ºclosed±loop enable temperatureº
when 2 min. or more after engine start
When the temperature at the time of engine starting is
±19.45 to ±8.34°C (±3 to 17°F)Engine coolant temperature is less than ºclosed±loop enable temperatureº
when 5 min. or more after engine start
When the temperature at the time of engine starting is
±19.45°C (±3°F) or lessEngine coolant temperature is less than ºclosed±loop enable temperatureº
when 20 min. or more after engine start
INSPECTION PROCEDURE
HINT:
If DTC P0115, P0116, P0117, P0118 and P0125 are output simultaneously, engine coolant tempera-
ture sensor circuit may be open or short. 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.
1 Are there any other codes (besides DTC P0125) being output?
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 / DTC
INFO / CURRENT CODES.
CHECK:
Read the DTCs using the hand±held tester.
RESULT:
Display (DTC output)Proceed to
P0125A
ºP0125º and other DTCsB
HINT:
If any other codes besides ºP0125º are output, perform the troubleshooting for those DTCs first.
B Go to relevant DTC chart (See page DI±58).
A

Page 335 of 4323

TOYOTA SEQUOIA 2001 Service Repair Manual ± DIAGNOSTICSENGINE
DI±141
335 Author: Date:
2005 SEQUOIA (RM1146U)
2 Inspect thermostat (See page CO±12).
CHECK:
Check the valve opening temperature of the thermostat.
OK:
Valve opening temper

Page 336 of 4323

TOYOTA SEQUOIA 2001 Service Repair Manual A20488A21045
Threshold
(75C (167F))Estimated ECT
5 sec.
Indicated coolant temp. reading
DTC set (after 2 driving cycle) ECT
Time DI±142
± DIAGNOSTICSENGINE
336 Author: Date:
2005 SEQUOIA (RM1

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