2001 TOYOTA SEQUOIA engine starting

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

DI±554
± DIAGNOSTICSAUTOMATIC TRANSMISSION
748 Author: Date:
2005 SEQUOIA (RM1146U) Shift point too high or too low
1. Shift solenoid valve (SLT) circuit *1
2. Speed sensor NT circuit *1
3. Speed sensor SP2 circuit *1
4. Throttle position sensor circuit *1
5. ATF temperature sensor circuit *1
6. ECM
DI±662
DI±591
DI±596
DI±58
DI±582
IN±35
Up±shift to 5th from 4th while shift lever is in 4 position1. O/D main switch circuit
2. ECMDI±688
IN±35
Up±shift to 5th from 4th while engine is cold1. Engine coolant temp. sensor circuit *1
2. ECM
DI±58
IN±35
Up±shift to 4th from 3rd while shift lever is in 3 position1. Park/neutral position switch circuit *1
2. ECM
DI±576
IN±35
Up±shift to 3rd from 2nd while shift lever is in 2 position1. Park/neutral position switch circuit *1
2. ECM
DI±576
IN±35
Up±shift to 2nd from 1st while shift lever is in L position1. Shift position L switch circuit
2. ECMDI±691
IN±35
Harsh engagement (N " D)
1. Speed sensor NT circuit *1
2. Shift solenoid valve (SL1) circuit *1
3. Shift solenoid valve (SLT) circuit *1
4. ECM
DI±591
DI±603
DI±662
IN±35
Harsh engagement (Lock±up)
1. Speed sensor NT circuit *1
2. Speed sensor SP2 circuit *1
3. Shift solenoid valve (SLU) circuit *1
4. ECM
DI±591
DI±596
DI±680
IN±35
Harsh engagement (Any driving position)ECMIN±35
Poor acceleration
1. ATF temperature sensor No.2 circuit *1
2. Engine coolant temp. sensor circuit *1
3. Shift solenoid valve (SLT) circuit *1
4. ECM
DI±666
DI±58
DI±662
IN±35
No engine brakingECMIN±35
No kick±downECMIN±35
Engine stalls when starting off or stopping1. Shift solenoid valve (SLU) circuit *1
2. ECM
DI±680
IN±35
AT Oil Temp. warning light remains on1. ATF temperature sensor No.2 circuit*1DI±666
Lock±up at 3rd gear
1. AT F temperature sensor No.2 circuit 1
2. Engine coolant temp. sensor circuit *1DI±666
DI±58
Shift point too high
2. Engine coolant tem . sensor circuit
3. ECMDI 58
IN±35
Malfunction in shifting1. Park/neutral position switch circuit *1
2. ECM
DI±576
IN±35

DI±556
± DIAGNOSTICSAUTOMATIC TRANSMISSION
750 Author: Date:
2005 SEQUOIA (RM1146U) Harsh engagement (4th " 5th)
1. Shift solenoid valve (SL1)
2. Shift solenoid valve (SL2)
3. Valve body assy
4. Off±vehicle repair matrix chartDI±620
DI±625
AT±10
±
Harsh engagement (5th " 4th)
1. Shift solenoid valve (SL1)
2. Shift solenoid valve (SL2)
3. Valve body assy
4. Off±vehicle repair matrix chartDI±620
DI±625
AT±10
±
Slip or shudder (Forward and reverse)
1. Transmission control cable
2. Valve body assy
3. Oil strainer
4. Off±vehicle repair matrix chartDI±524
AT±10
AT±10
±
No engine braking (1st: L position)1. Valve body assy
2. Off±vehicle repair matrix chartAT±10
±
No engine braking (2nd: 2 position)1. Valve body assy
2. Off±vehicle repair matrix chartAT±10
±
No kick±downValve body assyAT±10
Shift point too high or too low
1. Shift solenoid valve (SLT)
2. Shift solenoid valve (SL1)
3. Valve body assyDI±656
DI±620
AT±10
Poor acceleration1. Shift solenoid valve (SLT)
2. Valve body assyDI±656
AT±10
Engine stalls when starting off or stopping1. Shift solenoid valve (SLU)
2. Valve body assyDI±672
AT±10

DI±558
± DIAGNOSTICSAUTOMATIC TRANSMISSION
752 Author: Date:
2005 SEQUOIA (RM1146U) No engine braking (1st: L position)
Brake No. 4 (B4)

No engine braking (2nd: 2 position)Brake No. 2 (B2)

No engine braking (3rd: 3 position)Brake No. 1 (B1)

Poor acceleration (All positions)Torque converter clutchAT±30
Poor acceleration (5th)
1. Clutch No. 1 (C1)
2. Clutch No. 3 (C
3)
3. Brake No. 1 (B
1)
4. Front planetary gear unit








Engine stalls when starting off or stoppingTorque converter clutchAT±30

DIDJ2±01
± DIAGNOSTICSAUTOMATIC TRANSMISSION
DI±567
761 Author: Date:
2005 SEQUOIA (RM1146U)
FAIL±SAFE CHART
1. FAIL±SAFE
This function minimizes the loss of the ECT functions when any malfunction occurs in a sensor or solenoid.
Malfunction PartFunction
Output Speed Sensor (SP2)During an output speed sensor malfunction, shift control is effected through the
input speed sensor signal (NT).
ATF Temp. Sensor No. 1During an ATF temperature sensor No. 1 malfunction, up±shift to the 5th and flex
lock±up clutch control are prohibited.
Shift Solenoid Valve S1, S2 and SR
The current to the failed solenoid valve is cut off and control is effected by operating
the other solenoid valves with normal operation.
Shift control is effected depending on the failed solenoid as described in the table
on the next page.
Shift Solenoid Valve SL1 and SL2During a solenoid valve SL1 or SL2 malfunction, up±shift to the 5th is prohibited.
Shift Solenoid Valve SLU
During a solenoid valve SLU malfunction, the current to the solenoid valve is
stopped. This stops lock±up control and flex lock±up control, fuel economy de-
creases.
Shift Solenoid Valve SLT
During a solenoid valve SLT malfunction, the current to the solenoid valve is
stopped. This stops line pressure optimal control, the shift shock increases. How-
ever, shifting is effected through normal clutch pressure control.
Fail Safe Function:
If either of the shift solenoid valve circuits has an open or short failure, the ECM turns the other shift solenoid
ºONº and ºOFFº in order to shift into the gear positions shown in the table below.
In case of a short circuit, the ECM stops sending current to the short circuited solenoid.
Even if starting the engine again in the fail±safe mode, the gear position remains in the same position.

DI±592
± DIAGNOSTICSAUTOMATIC TRANSMISSION
786 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR DESCRIPTION
This DTC indicates that pulse is not output from the speed sensor NT (Turbine (input) speed sensor ) or is
output only little. The NT terminal of the ECM detects the revolving signal from the speed sensor (NT) (input
RPM). The ECM outputs a gearshift signal comparing the
input speed sensor (NT) with the output speed
sensor (SP2).
While the vehicle is operating in the 4th or 5th gear position in the shift position of D, if the input shaft revolu-
tion is less than 300 rpm
*1 although the output shaft revolution is more than 1000 rpm or more*2, the ECM
detects the trouble, illuminates the MIL and stores the DTC.
*1: Pulse is not output or is irregularly output.
*2: The vehicle speed is approx. 50 km/h (31 mph) or more.
MONITOR STRATEGY
Related DTCsP0717Speed sensor (NT)/Verify pulse input
Rid /C tMainSpeed sensor (NT)Required sensors/ComponentsSubSpeed sensor (NO)
Frequency of operationContinuous
Duration5 sec.
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not present.See page DI±545
Shift changeShift change is completed and before starting next shift change operation
ECM selected gear4th or 5th
Output shaft rpm1,000 rpm or more±
NSW switchOFF
R switchOFF
L switchOFF
EngineRunning
Ignition switchON
StarterOFF
TYPICAL MALFUNCTION THRESHOLDS
Detection criteriaThreshold
Sensor signal rpmLess than 300 rpm
COMPONENT OPERATING RANGE
ParameterStandard value
Speed sensor (NT)Input speed is equal to engine speed when lock±up ON.

± DIAGNOSTICSAUTOMATIC TRANSMISSION
DI±609
803 Author: Date:
2005 SEQUOIA (RM1146U) Shift solenoid valve SL2 circuit
Not circuit malfunction
ECT (Engine coolant temperature) sensor
circuitNot circuit malfunction
KCS sensor circuitNot circuit malfunction
ETCS (Electric throttle control system)Not system down
Transmission rangeºDº
ECT40°C (104°F) or more±
Spark advance from Max. retard timing by
KCS control0° CA or more±
EngineStarting
Transfer rangeºHIGHº*1
Transfer range ºHIGHº *1 (This condition is applied only 4WD)
*1 Following conditions met
Vehicle speed sensor circuitNot circuit malfunction
Output shaft speed sensor circuitNot circuit malfunction
Transfer output speed143 rpm or more±
NO/NOtf (Transfer input speed/Transfer
output speed)0.9 to 1.1
OFF malfunction (A)
ECM selected gear1st
Vehicle speed2 to 40 km/h (1.2 to 24.9 mph)
Throttle valve opening angle
8% or more
and 7.0% or more at 2,000 rpm
(Conditions vary with engine speed)
±
OFF malfunction (B)
Current ECM selected gear5th
Last ECM selected gear4th
Continuous time for ECM selecting 4th
gear2 sec. or more±
Actual gear when ECM selected 4th gear4th
OFF malfunction (C)
Current ECM selected gear5th
Last ECM selected gear4th
ON malfunction (A)
ECM selected gear1st
Vehicle speed2 to 40 km/h (1.2 to 24.9 mph)
Throttle valve opening angle7.0% or more at 2,000 rpm
(Conditions vary with engine speed)±
ON malfunction (B)
ECM selected gear4th
Vehicle speed2 km/h (1.2 mph) or more±
Throttle valve opening angle7.0% or more at 2,000 rpm
(Conditions vary with engine speed)±
ON malfunction (C)
ECM selected gear3rd
Vehicle speed2 km/h (1.2 mph) or more±