Page 13 of 2000
ENGINE - 2AZ-FE ENGINE
01NEG35Y
Throttle Body
To H e a t e r C o r e
To R a d i a t o r
Thermostat
From Radiator Wa t e r P u m pBypass Passage
01NEG59Y
Bypass PassageCylinder Head
Wa t e r P u m p
Cylinder Block
Thermostat
Reservoir
Ta n k
RadiatorThrottle
BodyHeater Core EG-16
COOLING SYSTEM
The cooling system uses a pressurized forced-circulation system with pressurized reservoir tank.
A thermostat with a bypass valve is located on the water inlet housing to maintain suitable temperature
distribution in the cooling system.
An aluminum radiator core is used for weight reduction.
The flow of the engine coolant makes a U-turn in the cylinder block to ensure a smooth flow of the engine
coolant. In addition, a bypass passage is enclosed in the cylinder head and the cylinder block.
Warm water from the engine is sent to the throttle body to prevent freeze-up.
The TOYOTA genuine Super Long Life Coolant (SLLC) is used.
System Diagram
Page 23 of 2000
ENGINE - 2AZ-FE ENGINE
01NEG45Y
RegulatorB
M
IG
RLO
L
Ignition Switch
To Discharge
Wa r n i n g L i g h t
Generator
ECM
281EG13
281EG12
Coil SpringPulley
Helical Coil Type One-way Clutch EG-26
Wiring Diagram
2. Generator Pulley
A helical coil type one-way clutch is used on the generator pulley in order to reduce the load that acts on
the auxiliary equipment belt.
The pulley mounting nut and the generator pulley have been integrated to achieve a compact construction.
Page 31 of 2000
ENGINE - 2AZ-FE ENGINE
01MEG09Y
Accelerator Pedal
Position Sensor
Generator
MIL
DLC3Park / Neutral
Position Switch
Ignition
Switch
Circuit Opening RelayECM
Battery
Throttle
Position
Sensor
Throttle
Control
Motor
Purge VSVMass Air Flow Meter
Intake Air Temperature
Sensor
Camshaft Position
Sensor
Camshaft
Timing
Oil Control
Va l v e
Ignition Coil
with Igniter
Injector
Knock Sensor
Engine
Coolant
Temperature
Sensor
Crankshaft Position
Sensor
Canister
Filter
Fuel Pump
Canister Pump Module
Ve n t Va l v e
Leak Detection Pump
Canister Pressure SensorTWCs
Heated Oxygen Sensor
(Bank 1, Sensor 2)
Air-fuel Ratio Sensor
(Bank 1, Sensor 1) EG-34
3. Engine Control System Diagram
Page 40 of 2000

ENGINE - 2AZ-FE ENGINE
00REG17Y
Accelerator Pedal
Position SensorThrottle Valve
Throttle Position SensorThrottle
Control
Motor
Mass Air
Flow MeterECMSkid
Control
ECU
Ignition
CoilFuel
Injector
: CANEG-43
6. ETCS-i (Electronic Throttle Control System-intelligent)
General
The ETCS-i is used, providing excellent throttle control in all the operating ranges. In the 2AZ-FE
engine, the accelerator cable has been discontinued, and an accelerator pedal position sensor has been
provided on the accelerator pedal.
In the conventional throttle body, the throttle valve opening is determined by the amount of the
accelerator pedal effort. In contrast, the ETCS-i uses the ECM to calculate the optimal throttle valve
opening that is appropriate for the respective driving condition and uses a throttle control motor to control
the opening.
The ETCS-i controls the IAC (Idle Air Control) system, the TRAC (Traction Control), VSC (Vehicle
Stability Control) system and curise control system.
In case of an abnormal condition, this system switches to the limp mode.
System Diagram
Page 49 of 2000

ENGINE - 2AZ-FE ENGINE
01NEG09Y
01NEG10Y
Air
Conditioning
ECU
Engine Coolant
Temperature SensorFANL
ECM
FA N HCooling Fan
Relay No.3
Cooling Fan
Motor No.2
Cooling Fan
Relay No.1
Cooling Fan
Motor No.1
Low Speed (Series Connection)
High Speed (Parallel Connection) Air
Conditioning
ECU
Engine Coolant
Temperature SensorFA N L
ECM
FA N HCooling Fan
Relay No.3
Cooling Fan
Motor No.2
Cooling Fan
Relay No.1
Cooling Fan
Relay No.2
Cooling Fan
Motor No.1 : CAN
Cooling Fan
Relay No.2
EG-52
8. Cooling Fan Control
On the models with air conditioning, the ECM controls the operation of the cooling fan in two speeds (Low
and High) based on the engine coolant temperature sensor signal and the air conditioning ECU signal. This
control is accomplished by operating the 2 fan motors in 2 stages through low speed (series connection) and
high speed (parallel connection).
Wiring Diagram
Cooling Fan Operation
Air Conditioning ConditionEngine Coolant Temperature C (F)
A / C CompressorRefrigerant Pressure94 (201.2) or lower95.5 (203.9) or higher
OFF1.2 MPa (12.5 kgf / cm2, 178 psi) or lowerOFFHigh
ON1.2 MPa (12.5 kgf / cm2, 178 psi) or lowerLowHighON1.2 MPa (12.5 kgf / cm2, 178 psi) or higherHighHigh
Page 52 of 2000

ENGINE - 2AZ-FE ENGINE
00REG22Y
To Intake Manifold
Purge VSV
Purge Air
Line
ECMFuel Tank
Canister Filter
Fresh Air LineRefueling Valve
Canister Pump Module
Ve n t
Va l v e
Leak Detection Pump
& Pump Motor
Canister
Pressure SensorCanisterP M
EG-55
System Diagram
Function of Main Components
ComponentFunction
CanisterContains activated charcoal to absorb the vapor gas that is created in the
fuel tank.
Refueling
Controls the flow rate of the vapor gas from the fuel tank to the canister
when the system is purging or during refueling.
Refueling
Va l v eRestrictor PassagePrevents a large amount of vacuum during purge operation or system
monitoring operation from affecting the pressure in the fuel tank.
Fresh Air LineFresh air goes into the canister and the cleaned drain air goes out into
the atmosphere.
Vent ValveOpens and closes the fresh air line in accordance with the signals from
the ECM.
Canister
Pump ModuleLeak Detection
PumpApplies vacuum pressure to the EVAP control system in accordance
with the signals from the ECM.
p
Canister
Pressure SensorDetects the pressure in the EVAP control system and sends the signals
to the ECM.
Purge VSV
Opens in accordance with the signals from the ECM when the system
is purging, in order to send the vapor gas that was absorbed by the
canister into the intake manifold. In system monitoring mode, this valve
controls the introduction of the vacuum into the fuel tank.
Canister FilterPrevents dust and debris in the fresh air from entering the system.
ECM
Controls the canister pump module and purge VSV in accordance with
the signals from various sensors, in order to achieve a purge volume that
suits the driving conditions. In addition, the ECM monitors the system
for any leakage and outputs a DTC if a malfunction is found.
Page 54 of 2000
ENGINE - 2AZ-FE ENGINE
279EG26
D13N17 279EG25
Fresh Air
Canister
Pressure SensorLeak Detection Pump
Pump Motor
Vane PumpCanister
Pressure SensorVe n t Va l v e
Fresh Air
Canister
Canister Pump Module
Fresh AirVent Valve
Filter Filter
M
Leak Detection Pump
& Pump Motor
Canister
Pressure SensorP
Reference Orifice
[0.5 mm (0.02 in.) Diameter]Filter
To Canister
EG-57
3) Canister Pump Module
Canister pump module consists of the vent valve, leak detection pump, and canister pressure sensor.
The vent valve switches the passages in accordance with the signals received from the ECM.
A DC type brushless motor is used for the pump motor.
A vane type vacuum pump is used.
Simple Diagram
Page 62 of 2000

ENGINE - 2AZ-FE ENGINE
01NEG13Y
Generator
RegulatorB
DF
RLOECM
Various Electrical
Loads
Battery Current Sensor
Battery Temperature Sensor
Battery Voltage
Battery
Various Sensors and Switches
Throttle Position Sensor
Crankshaft Position Sensor
Accelerator Pedal Position
SensorEG-65
11. Charging Control
General
This system lowers the generated voltage when the vehicle is idling or is being driven at a constant speed,
and raises the generated voltage when the vehicle is decelerating. This reduces the load on the engine as
a result of the electric generation of the generator, thus contributing to the fuel economy of the engine.
During acceleration, this system regulates the generated voltage in order to place the amperage estimation
value close to the target value.
This control consists of the ECM, battery current sensor with a built-in battery temperature sensor,
generator, and various sensors and switches.
The ECM detects driving condition based on signals from various sensors and switches, and detects
charging condition based on signals from the generator, battery current sensor and battery temperature
sensor. Then the ECM outputs signals to the IC regulator to control the genetated voltage of the generator.
The ECM stops the charging control and the generator switches to normal power generation mode under
the following conditions:
Low battery capacity
Low or high battery temparature
Wipers operating or blower motor operating with tail lamp relay ON
System Diagram