2001 TOYOTA PRIUS Service Repair Manual

ENGINE ± 1NZ-FXE ENGINE
TDC
EX IN
To
advance
side
BDC
EX IN
To
retard side
Latest timing
EX IN
EX INLatest timing 72
Operation State
RangeValve TimingObjectiveEffect
In Low to
Medium
Speed Range
with Heavy
Load
4
182EG29
Advancing the intake
valve close timing for
volumetric efficiency
improvement
Improved
torque in
low to
medium
speed
range
In High Speed
Range with
Heavy Load
5
182EG30
Retarding the intake
valve close timing for
volumetric efficiency
improvement
Improved
output
At Low
TemperaturesÐ
182EG26
Eliminating overlap to
prevent blow back to the
intake side for reduction
of fuel increase at low
temperatures, and
stabilizing the idling rpm
for decreasing fast idle
rotation
Stabilized
fast idle
rpm Better
fuel
economy
Upon
Starting /
Stopping the
Engine
Ð
182EG26
Eliminating overlap to
eliminate blow back to
the intake sideImproved
startability

ENGINE ± 1NZ-FXE ENGINE
182EG39
Front Airbag
Sensors
(RH and LH)Airbag
Sensor
AssemblyHV
ECUCircuit
Opening
Relay
Fuel Pump
Motor ECM73
7. Fuel Pump Control
A fuel cut control is adopted to stop the fuel pump when the SRS airbag is deployed, thus helping reduce fuel
leakage.
In this system, the airbag deployment signal from the airbag sensor assembly is detected by the HV ECU,
send the signal to ECM, which turns OFF the circuit opening relay.
After the fuel cut control has been activated, turning the ignition switch from OFF to ON cancels the fuel cut
control, thus engine can be restarted.

ENGINE ± 1NZ-FXE ENGINE
182EG31
Accelerator Pedal
Position SensorThrottle Valve
Throttle Position Sensor
Throttle Control
Motor
HV
ECUECM
182EG33 182EG32
Accelerator Pedal
Position Sensor(V)
5.0
4.0
3.0
2.0
1.0
0 10 2030 405060 70 80
125Output Voltage
Accelerator Pedal Depressed AngleVPA2
VPA1 74
8. ETCS-i (Electronic Throttle Control System-intelligent)
General
The ETCS-i, which realizes excellent throttle control in all the operating ranges, has been adopted.
In the conventional throttle body, the throttle valve opening is determined invariably by the amount of
the accelerator pedal effort. In contrast, the ETCS-i used 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 ISC (Idle Speed Control) system and the cruise control system.

System Diagram 
Construction
1) Accelerator Pedal Position Sensor
The accelerator pedal position sensor is mounted on the accelerator pedal. To detect the pedal opening
angle, 2 separate systems consisting of main and sub sensors are used, and 2 separate return springs are
used to improve reliability. In the detecting portions, Hall elements have been adopted. Due to the charac-
teristics of the Hall elements, different signals are output depending on whether the pedal is pressed all
the way or is released. To correct these signals, a mechanical device has been provided to detect the cor-
rect pedal opening angle. The sensors of the 2 systems output the same signals.

ENGINE ± 1NZ-FXE ENGINE
150EG39150EG40
Close
Open
VC VTA1 VTA2 E2V
5
0 Close
Output Voltage
Open VTA1 VTA2
Accelerator Pedal Depressed Angle75
2) Throttle Position Sensor
The throttle position sensor is mounted on the throttle body.
The throttle position sensor converts the amount of accelerator pedal effort into two types of electrical
signals with distinct output characteristics. The signals are then input into the ECM.
3) Throttle Control Motor
A DC motor with excellent response and minimal power consumption is used for the throttle control mo-
tor. The ECM performs the duty ratio control of the direction and the amperage of the current that flows
to the throttle control motor in order to regulate the opening angle of the throttle valve.
Operation
The ECM drives the throttle control motor by determining the target throttle valve opening in accordance
with the respective operating condition.
1) Idle Speed Control
The idle speed control is effected entirely by the ETCS-i. The following are the contents of the control:
idle-up control during cold engine operation, intake air volume control to improve the startability of the
engine, and control for when the electrical load changes such as when the air conditioning switch is turned
ON or OFF.
2) Cruise Control
Through the adoption of the ETCS-i, the vehicle speed is now controlled by the throttle control motor,
which controls the throttle valve.