engine starting TOYOTA SEQUOIA 2001 Service Repair Manual

Important Points in the Customer Problem Analysis
 What ±±±±± Vehicle model, system name
 When ±±±±± Date, time, occurrence frequency
 Where ±±±±± Road conditions
 Under what conditions? ±±±±± Running conditions, driving conditions, weather conditions
 How did it happen? ±±±±± Problem symptoms
(Sample) Engine control system check sheet.
ENGINE CONTROL SYSTEM Check Sheet
Customer's Name
Driver's Name
Data Vehicle
Brought in
License No.
Model and Model
Year
Frame No.
Engine Model
Odometer Reading
km
miles
Problem Symptoms
Engine does
not Start
Difficult to
Start
Poor Idling
Poor
Drive ability
Engine Stall
Others
Engine does not crankNo initial combustionNo complete combustion
Engine cranks slowly
Other
Incorrect first idleIdling rpm is abnormalHigh ( rpm)Low ( rpm)
Rough idling
Other
HesitationBack fireMuffler explosion (after±fire)Surging
Knocking
Other
Soon after startingAfter accelerator pedal depressed
After accelerator pedal released
During A/C operation
Shifting from N to D
Other
Data Problem
ConstantSometimes ( times per day/month)
Inspector's
Name
CUSTOMER PROBLEM ANALYSIS CHECK
± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN±25
25 Author: Date:
2005 SEQUOIA (RM1146U)
1. CUSTOMER PROBLEM ANALYSIS
In troubleshooting, the problem symptoms must be confirmed accurately and all preconceptions must be
cleared away in order to give an accurate judgment. To ascertain just what the problem symptoms are, it is
extremely important to ask the customer about the problem and the conditions at the time it occurred.
Important Point in the Problem Analysis:
The following 5 items are important points in the problem analysis. Past problems which are thought to be
unrelated and the repair history, etc. may also help in some cases, so as much information as possible should
be gathered and its relationship with the problem symptoms should be correctly ascertained for reference
in troubleshooting. A customer problem analysis table is provided in Diagnostics section for each system
for your use.

V07268
VIBRATION METHOD: When vibration seems to be the major cause.
CONNECTORS
WIRE HARNESS
PARTS AND SENSOR1
Slightly shake the connector vertically and horizontally.
Slightly shake the wire harness vertically and horizontally.
The connector joint, fulcrum of the vibration, and body
through portion are the major areas to be checked thorough-
ly.
Apply slight vibration with a finger to the part of the sensor
considered to be the problem cause and check that the mal-
function occurs.Shake Slightly
Swing Slightly
Vibrate Slightly
HINT:
Applying strong vibration to relays may result in open relays.
± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN±29
29 Author: Date:
2005 SEQUOIA (RM1146U)
3. SYMPTOM SIMULATION
The most difficult case in troubleshooting is when there are no problem symptoms occurring. In such cases,
a thorough customer problem analysis must be carried out, then simulate the same or similar conditions and
environment in which the problem occurred in the customer's vehicle. No matter how much experience a
technician has, or how skilled he may be, if he proceeds to troubleshoot without confirming the problem
symptoms he will tend to overlook something important in the repair operation and make a wrong guess
somewhere, which will only lead to a standstill. For example, for a problem which only occurs when the en-
gine is cold, or for a problem which occurs due to vibration caused by the road during driving, etc., the prob-
lem can never be determined so long as the symptoms are confirmed with the engine hot or the vehicle at
a standstill. Since vibration, heat or water penetration (moisture) is likely cause for problem which is difficult
to reproduce, the symptom simulation tests introduced here are effective measures in that the external
causes are applied to the vehicle in a stopped condition.
Important Points in the Symptom Simulation Test:
In the symptom simulation test, the problem symptoms should be confirmed, but the problem area or parts
must also be found out. To do this, narrow down the possible problem circuits according to the symptoms
before starting this test and connect a tester beforehand. After that, carry out the symptom simulation test,
judging whether the circuit being tested is defective or normal and also confirming the problem symptoms
at the same time. Refer to the problem symptoms table for each system to narrow down the possible causes
of the symptom.

DI3H9±07
ENGINE CONTROL SYSTEM Check Sheet
Customer's Name
Driver's Name
Data Vehicle
Brought in
Engine model
VIN
Production Date
Licence Plate No.
Odometer Reading
Problem Symptoms
Engine does
not Start
Difficult to
Start
Poor Idling
Poor
Driveability
Engine Stall
Others
Engine does not crankNo initial combustionNo complete combustion
Engine cranks slowly
Other
Incorrect first idleIdling rpm is abnormalHigh ( rpm)Low ( rpm)
Rough idling
Other
HesitationBack fireMuffler explosion (after±fire)Surging
Knocking
Other
Soon after startingAfter accelerator pedal depressed
After accelerator pedal released
During A/C operation
Shifting from N to D
Other
Dates Problem
Occurred
Problem Frequency
Condition When
Problem Occurs
Weather
Engine Operation
Engine Temp. Place Outdoor
TemperatureConstant
Sometimes ( times per day/month)Once only
Other
Fine
CloudyRainySnowyVarious/Other
Hot
Warm CoolCold (approx. °C/ °F)
Highway
SuburbsInner cityUphillDownhill
Rough road
Other
Cold
Warming upAfter warming upAny temp.Other
Starting
Just after starting ( min.)IdlingRacing
Driving
Constant speedAccelerationDeceleration
A/C switch ON/OFF
Other
Condition of malfunction indicator lightRemains on Sometimes lights up Does not light up
NormalMalfunction code(s) (code )
Freeze frame data ( )
NormalMalfunction code(s) (code )
Freeze frame data ( )
Normal Mode
(Pre±check)
Check Mode DTC InspectionInspector's
Name
km
miles
(MIL)
DI±10
± DIAGNOSTICSENGINE
204 Author: Date:
2005 SEQUOIA (RM1146U)
CUSTOMER PROBLEM ANALYSIS CHECK

DI±30
± DIAGNOSTICSENGINE
224 Author: Date:
2005 SEQUOIA (RM1146U)
(a) Preconditions
The monitor will not run unless:

MIL is OFF

Fuel level is approximately 1/2 to 3/4

Altitude is 7,800 feet (2,400 m) or less

Engine Coolant Temperature (ECT) is between 4.4°C and 35°C (40°F and 95°F)

Intake Air Temperature (IAT) is between 4.4°C and 35°C (40°F and 95°F)

Cold Soak Procedure has been completed

Before starting the engine, the difference between ECT and IAT must be less than 7°C (13°F)
HINT:
Examples:

Scenario 1
ECT = 24°C (75°F)
IAT = 16°C (60°F)
Difference between ECT and IAT is 8°C (15°F)
" The monitor will not run because difference between ECT and IAT is higher than 7°C (13°F)

Scenario 2
ECT = 21°C (70°F)
IAT = 20°C (68°F)
Difference between ECT and IAT is 1°C (2°F)
" The monitor will run because difference between ECT and IAT is less than 7°C (13°F)
The readiness test can be completed in cold ambient conditions (less than 40°F / 4.4°C) and/or at
high altitudes (more than 7,800 feet / 2,400 m) if the drive pattern is repeated a second time after cycl-
ing the ignition off.
(b) Drive Pattern
(1) Connect the OBD II scan tool to DLC3 to check monitor status and preconditions (refer to (a)).
(2) Release pressure in fuel tank by removing the fuel tank cap and then reinstall it.
(3) Start the engine and allow it to idle until ECT becomes 75°C (167°F) or higher.
(4) Run the engine at 3,000 rpm for approximately 10 seconds.
(5) Allow the engine to idle with the A/C ON (to create slight load) for 15 to 50 minutes.
NOTICE:
If the vehicle is not equipped with A/C, put a slight load on the engine by doing the following :

Securely set the parking brake.

Block the drive wheels with wheel chocks.

Allow the vehicle to idle in drive for 15 to 50 minutes.

DI3HJ±10
± DIAGNOSTICSENGINE
DI±33
227 Author: Date:
2005 SEQUOIA (RM1146U)
PROBLEM SYMPTOMS TABLE
SymptomSuspect AreaSee page
Engine does not crank (Does not start)
22.Starter
23.Starter relay
24.Park/neutral position switchST±15
ST±17
DI±576
No initial combustion (Does not start)
1. ECM power source circuit
2. Fuel pump control circuit
3. Engine control module (ECM)DI±493
DI±509
IN±35
No complete combustion (Does not start)1. Fuel pump control circuitDI±509
Engine cranks normally but difficult to start
1. Starter signal circuit
2. Fuel pump control circuit
3. CompressionDI±298
DI±509
EM±3
Difficult to start with cold engine1. Starter signal circuit
2. Fuel pump control circuitDI±298
DI±509
Difficult to start with hot engine1. Starter signal circuit
2. Fuel pump control circuitDI±298
DI±509
High engine idle speed (Poor idling)1. A/C switch circuit
2. ECM power source circuit±
DI±493
Low engine idle speed (Poor idling)1. A/C switch circuit
2. Fuel pump control circuit±
DI±509
Rough idling (Poor idling)1. Compression
2. Fuel pump control circuitEM±3
DI±509
Hunting (Poor idling)1. ECM power source circuit
2. Fuel pump control circuitDI±493
DI±509
Hesitation/Poor acceleration (Poor driveability)1. Fuel pump control circuit
2. A/T faultyDI±509
±
Surging (Poor driveability)1. Fuel pump control circuitDI±509
Engine stalls soon after starting1. Fuel pump control circuitDI±509
Engine stalls during A/C operation1. A/C switch circuit
2. Engine control module (ECM)±
IN±35
Unable to refuel/Difficult to refuel1. ORVR system±

± 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

± 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

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

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 (RM1146U)
DTC P0128 Coolant Thermostat (Coolant Temperature
Below Thermostat Regulating Temperature)
HINT:
This is the purpose of ºthermostatº malfunction detection.
CIRCUIT DESCRIPTION
If the engine coolant temperature does not reach 75°C (167°F) despite sufficient warm±up time has
elapsed.
DTC No.DTC Detection conditionTrouble Area
P0128
Condition (a), (b) and (c) are met:
(a) Cold start
(b) After sufficient warm±up time has elapsed
(c) Engine coolant temperature greater than 75°C (167°F)
Thermostat

Cooling system

Engine coolant temperature sensor

ECM
MONITOR DESCRIPTION
The ECM estimates the coolant temperature based on starting temperature, engine loads, and engine
speeds. The ECM then compares the estimated temperature with the actual ECT (Engine Coolant Tempera-
ture). When the estimated coolant temperature reaches 75C (167F), the ECM checks the actual ECT. If
the actual ECT is less than 75C (167F), the ECM will interpret this as a fault in the thermostat or engine
cooling system and set a DTC.
DICEQ±02

A21043
Starter Relay EFI Relay
Circuit Opening
Relay
Fuel Pump RelayMREL
FPRTr2
Tr1 EFI No.1
IGNECM
FC
NE Fuel Pump
Battery
StarterFuel Pump Resistor
AM2Ignition Switch
STA
Crankshaft Position
Sensor (NE Signal)
± DIAGNOSTICSENGINE
DI±179
373 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P0230 Fuel Pump Primary Circuit
CIRCUIT DESCRIPTION
In the diagram below, when the engine is cranked, current flows from terminal STAR of the ECM to the starter
relay coil and also current flows to terminal STA of the ECM (STA signal).
When the STA signal and NE signal are input to the ECM, the Tr1 is turned ON, current flows to the coil of
the circuit opening relay, the relay switches on, power is supplied to the fuel pump, and the fuel pump oper-
ates.
While the NE signal is generated (engine running), the ECM keeps the Tr1 ON (circuit opening relay ON)
and the fuel pump also keeps operating.
The fuel pump speed is controlled at two levels (high speed or low speed) by the condition of the engine
(starting, light load, heavy load). When the engine starts (STA ON), the Tr2 in the ECM is OFF, so the fuel
pump relay closes and battery positive voltage is applied directly to the fuel pump. The fuel pump operates
at high speed.
After the engine starts while idling or light loads, since the Tr2 goes ON, power is supplied to the fuel pump
via the fuel pump resistor. The fuel pump operates at low speed.
DICEW±02