2001 TOYOTA PRIUS stop start

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.

THS (TOYOTA HYBRID SYSTEM)
182TH24
ªREADYº LightOutput Control
Warning Light 26
DRIVING CHARACTERISTICS
Because the Prius uses a parallel series hybrid system, some aspects of its operation may differ from those of
existing automobiles, and may require precautions that are unique to this system.
1. Starting the THS
Make sure that the parking brake is engaged and that the shift lever is in the P position.
While depressing the brake pedal, turn the ignition switch to the START position. After this, the ªREADYº
light flashes.
The engine does not start when the shift lever is in the N position; it can only start in the P position. When
the external air temperature is low, the ªREADYº light may flash longer than usual.
As soon as the engine has started, the ªREADYº light illuminates steadily and a beeping sound is heard.
Several seconds after the engine warms up, the engine stops automatically, provided that the air conditioning
compressor does not need to operate and that the HV battery maintains a proper SOC (state of charge).
2. Start-Off
While keeping the brake pedal depressed, release
the parking brake, and move the shift lever to the
D position.
The vehicle has the same creeping movement as
the conventional automatic transmission vehicles.
Gradually release the brake pedal and slowly de-
press the accelerator pedal to start off.
At this time, the vehicle starts off powered only by
the MG2 (Motor Generator No.2)
NOTICE: The vehicle can be started off, provided that the ªREADYº light remains illuminated, even
if the engine remains stopped.
3. Acceleration
Depress the accelerator pedal to accelerate the vehicle.
If the engine remained stopped during start-off, the engine will start automatically during acceleration.
4. Downhill Driving
Move the shift lever to the B position as necessary in order to simultaneously apply the regenerative brake
and the engine friction brake.
5. Deceleration and Stopping
Depress the brake pedal to decelerate and to stop the vehicle.
Depressing the brake pedal causes the regenerative brake to activate automatically in the D or B position. (In
the regenerative brake system, kinetic energy is converted to electrical energy.) If the engine has warmed up,
the air conditioning compressor does not need to operate, and if the HV battery maintains a proper SOC (state
of charge), the engine stops automatically when the vehicle speed drops-even if the vehicle comes to a stop.
6. Parking
Push down the parking brake pedal, move the shift lever to the P position, and pull out the ignition key.
NOTICE: Make sure to pull out the ignition key after parking the vehicle because the vehicle can be
driven as long as the ªREADYº light remains illuminated even if the engine is stopped.
7. Other Characteristics and Precautions

If a drive wheel slips on slippery terrain, causing the front wheels to spin faster than the rear wheels, the
THS effects control to limit the slippage by restraining the drive force. (This also protects the planetary
gear from damage.)

When the HV battery temperature is too high or low, the output control warning light illuminates, alerting
the driver that output power may be limited.
This is not 2 malfunction. This condition may be corrected by avoiding sudden acceleration /decelaration,
after which the light will go out.

When the vehicle is stopped and the shift lever is in the N position, electricity is not generated even if the
engine is running. If the vehicle remains stopped for a long time, make sure to move the shift lever to the
P position. In heavy traffic, keep the shift lever in the D position.

CHASSIS ± P111 HYBRID TRANSAXLE
182CH77 182CH06
Planetary
Gear UnitRing Gear
Carrier
Sun Gear
MG2
Oil PumpMG1
Transaxle
Damper
Engine
Chain
Counter Gear
Final Gear
MG2
Engine Output Shaft
MG1
182CH08
182CH07
HV Battery
Inverter
MG2 MG1
Engine : Flow of
: motive force
: Flow of
: electrical force
Discharge
Reactive
Control: Torque
: MG2
: Torque
Sun GearCarrier Ring Gear
rpm
MG1 Engine MG2
Nomographic Chart of Planetary
Gear Unit
82
5. Power Splitting Device
General
Planetary gear unit is used for a power splitting device.
As part of the planetary gear unit, the sun gear is connected to MG1, the ring gear is connected to MG2,
and the carrier is connected to the engine output shaft. The motive force is transmitted via the chain to the
counter drive gear.
Item
Connection
Sun GearMG1
Ring GearMG2
CarrierEngine Output Shaft
Operation
1) Starting the Engine
Both while the vehicle is stopped and is in motion, the starting of the engine is performed by MG1. Be-
cause the motive force is transmitted at this time to the ring gear in the planetary gear unit, an electrical
current is applied to MG2 to cancel out the motive force (reactive control).
The nomographic chart below gives a visual representation of the planetary gear's rotational direction,
rotational speed, and power balance. In the nomographic chart, the rpm of the 3 gears maintain a relation-
ship in which they are invariably joined by a direct line.

CHASSIS ± P111 HYBRID TRANSAXLE
182CH10
182CH09
: Flow of
: motive force
: Flow of
: electrical force
RechargingInverterHV Battery
Reactive
Control
MG2MG1Generate
EngineSun Gear Carrier Ring Gear
rpm
MG1 Engine MG2
: Torque
: MG2
: Torque
Nomographic Chart of Planetary
Gear Unit
Discharge
182CH12
182CH11
Inverter
HV Battery
Discharge
Drive
MG2
MG1
Engine : Flow of
: motive force
: Flow of
: electrical force
Sun Gear Carrier Ring Gear
rpm
MG1Engine
MG2
Nomographic Chart of Planetary
Gear Unit
: Driving
: Load
: MG2
: Torque
83
2) Generation During Shift Position P
When the shift lever is in the P position, if the SOC (State Of Charge) of the HV batteries exceeds the
specified value, the engine remains stopped. However, if the SOC is below the specified value, the engine
operates to generate electricity through MG1 in order to recharge the HV batteries. At this time, reactive
control is effected to allow the electric current to flow from the HV batteries to MG2, thus receiving the
reactive force of MG2.
3) Starting and Light-Load Driving
When the vehicle is started off or is being driven under light-load conditions, and the SOC of the HV
batteries exceeds the specified value, the vehicle operates powered only by MG2. At this time, the engine
remains stopped, and MG1 is spinning in the opposite direction without generating electricity. If the SOC
is below the specified value, the engine operates to generate electricity through MG1 in order to recharge
the HV batteries.

B04762
IN±14
± INTRODUCTIONFOR ALL OF VEHICLES
14 Author: Date:
2001 PRIUS (RM778U)
(b) Actions to be taken when HV battery is depleted
NOTICE:
Leaving a vehicle alone for 2 ± 3 months may cause electric
discharge from HV battery.
When this happens, replace the HV battery.
4. INSPECTION MODE
HINT:

The PRIUS automatically stops the engine while the ve-
hicle is stopped with the engine warmed up and battery
well charged if the A/C compressor operation is not re-
quired. Therefore, even if the vehicle stops for any reason
such as a check of ignition timing, the inspection mode
should be activated when continuous operation of the en-
gine is required.

The PRIUS has a skid control as traction control function.
When the wheel speed of the front wheels exceeds that
of the rear wheels, this function restrains the wheel speed
of the front wheels. It is necessary to activate the inspec-
tion mode and reset the skid control when turning only the
front wheels using a speedometer tester.
Activation inspection mode (Without using a hand±held tester)
(1) Perform the following (2) through (6) within 60 sec.
(2) Turn the ignition switch ON from OFF.
(3) With the shift lever in P position, fully depress the
accelerator pedal 2 times.
(4) With the shift lever in N position, fully depress the
accelerator pedal 2 times.
(5) With the shift lever in P position, fully depress the
accelerator pedal 2 times.
(6) Activate the inspecting mode and check that the hy-
brid system error warning light on the multi±center
display flashes.
(7) Turning the ignition switch to START starts the en-
gine's continuous operation.
NOTICE:

The idling speed in the inspection mode is approx.
1,000 rpm. The number of revolutions will increase up
to 1,500 rpm if the accelerator pedal is depressed to
a degree of less than 60%, and up to 2,250 rpm in a
case of 60% or more.

If a diagnosis code is recorded when entering the in-
spection mode, the master warning light and the error
warning light on the multi±center display is lit.

± INTRODUCTIONFOR ALL OF VEHICLES
IN±15
15 Author: Date:
2001 PRIUS (RM778U)

When the master warning light is lit during operation
in the inspection mode, deactivate the inspection
mode and inspect the diagnosed area.
HINT:
When continuous operation of the engine is required for such
as an exhaust leakage inspection, it is advisable as an easier
way to turn ON the FULL switch of the air conditioner.
5. SPECIAL NOTES FOR VEHICLE INSPECTION
(a) Vehicle conditions
(1) Before activating the service mode, turn the air con-
ditioner off, start the engine with the shift lever at P
position, and check that the engine stops within
several seconds after starting. (Engine warm up
check)
(2) Activate the service mode and inspect the vehicle.
The shift position for each test is as follows:
Test itemShift lever position
1. Vehicle straight traveling test (side
slip inspection)D
2. Braking force testN
3. Speedometer testD
4. Exhaust gas test (idling)P
5. Headlight testP
(3) Reset the service mode immediately after comple-
tion of inspection.
NOTICE:
Traveling on a road without resetting the service mode may
damage the transaxle.
(b) Special notes for speedometer test
NOTICE:
Rapid starting or quick acceleration/deceleration based on
the speedometer tester without load setting may damage
the transaxle.
(1) Depress the accelerator pedal slowly and gradually
accelerate at the time of measurement.
(2) After the measurement, use the brake to decelerate
gradually and stop.
(c) Special note for using the chassis dynamometer
Always set an appropriate load before starting the test.
NOTICE:
Rapid starting or quick acceleration/deceleration with in-
sufficient load may damage the transaxle.

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±35
2001 PRIUS (RM778U)
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 condition 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 ex-
ternal 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 of course 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 symp-
toms 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 symp-
toms at the same time. Refer to the problem symptoms table for each system to narrow down the possible
causes of the symptom.