2001 TOYOTA PRIUS light

BODY ELECTRICAL ± ACCESSORIES
182BE46
Cruise Control Switch Signal
Brake Cancel Signal
(Stoplight Switch)
Accelerator Opening Angle Signal
(Accelerator Pedal Position Sensor)
Shift Position Signal
(Sift Position Sensor)
Brake ECUHV ECU
Cruise Control Area

Switch Input Value

Processing

Required Vehicle Speed

Calculation
Hybrid Control Area

Required Torque

Calculation

Drive Force Distribution

between Engine and
Electric Motor
Indicator Light
ECM
Inverter189
CRUISE CONTROL SYSTEM
1. General
The Prius has adopted a cruise control system that uses the hybrid system, and it is offered as an option. This
system, which is controlled by the HV ECU that is integrated with the cruise control ECU, operates the ve-
hicle through an optimal combination of the drive forces of the electric motor and the engine in accordance
with the setting on the cruise control switch.
2. Construction
The cruise control system mainly consists of an HV ECU, cruise control switches, indicator, stoplight switch,
accelerator pedal position sensor, and the shift position sensor.
The table below shows each of the functions.
Item
Function
HV ECUControls all the functions of the cruise control system in accordance with the
signals from the sensors.
Cruise Control Main
SwitchCruise control system's ON / OFF signal requirement.
Cruise Control Switch
A three-directional switch that provides the SET / COAST, RESUME /
ACCEL, and CANCEL functions. It requires the functions and settings in
accordance with its operations.
Indicator LightIt is provided in the combination meter to display whether the system is ON
or OFF.
Stop Light SwitchDetects that the driver has stepped on the brake pedal.
Accelerator Pedal
Position SensorDetects the accelerator pedal opening angle.
Shift Position SensorDetects the shift position.

BODY ELECTRICAL ± ACCESSORIES
182BE47 Warning
Buzzer
(Driver)
Seat Belt
Warning
Light
(Driver)Seat Belt
Warning Light
(Front Passenger Side)
Combination Meter
Seat Belt
Buckle
SwitchOccupant Detection
Sensor
Seat Belt Buckle
Switch
Driver
SideFront Passenger
Side
159BE19 159BE18
182BE53
Occupant Detection Sensor
Front Passenger Seat
Upside ViewSpacerElectrode Sheet
Electrode Sheet
Sensor OFF
Occupant
Sensor ON 190

SEAT BELT WARNING SYSTEM
1. General
A seat belt warning system has been adopted. If the driver's seat belt is not buckled, the warning light flashes
and the buzzer sounds. If the front passenger seat belt is not buckled, it flashes the warning light. When the
ignition switch is turned ON, this system determines whether or not the seat belt is buckled by the ON or OFF
condition of the switch that is provided in the seat belt buckle. The occupant detection sensor provided in
the seat cushion of the front passenger seat determines whether or not an occupant is seated in the front pas-
senger seat.
2. Occupant Detection Sensor
The occupant detection sensor, which is enclosed in the seat cushion of the front passenger seat, is used to
detect whether or not the front passenger seat is occupied.
This sensor, which is shaped as illustrated below, consists of a construction in which two sheets of electrodes
sandwich a spacer. When the occupant is seated, the electrode sheets come in contact with each other through
the hole that is provided in the spacer portion, thus enabling the current to flow.
Thus, the sensor detects whether or not an occupant is seated in the front passenger seat.

B04748
B04749
1. +Terminal
2. +Terminal3. ±Terminal
4. ±Terminal
B04750
± INTRODUCTIONFOR ALL OF VEHICLES
IN±13
13 Author: Date:
2001 PRIUS (RM778U)
2. PRECAUTIONS TO BE OBSERVED WHEN INSPECT-
ING OR SERVICING ENGINE COMPARTMENT
The PRIUS, automatically turns the engine ON and OFF when
the ignition switch is set to the ON position provided that the
READY light on the instrument panel is it.
Before inspecting or servicing the engine compartment, there-
fore, remove the ignition switch key.
3. ACTIONS TO BE TAKEN WHEN BATTERIES ARE DE-
PLETED
(a) Actions to be taken when the auxiliary battery is depleted
HINT:
The following phenomena indicate that the auxiliary battery is
depleted:

No display appears on the instrument panel when you
turn the ignition switch to the ON position.

The hybrid system does not start.

The headlights are dark.

The sound from the horn is weak.
NOTICE:
Never use a quick charger.
(1) Move the shift lever to the P position, and engage
the parking brake.
(2) Remove the ignition key plate from the ignition
switch.
(3) Using a booster cable, connect the 12 V battery of
the rescue vehicle and auxiliary battery of the
stalled vehicle, as shown in the illustration.
(4) Start the engine of the rescue vehicle and run the
engine at a speed slightly higher than the idling
speed for 5 minutes to charge the auxiliary battery
of the stalled vehicle.
(5) Turn the ignition switch of the stalled vehicle to the
START position to start the hybrid system.
If the hybrid system fails to start and the master and HV battery
warning lights come on, the HV battery may have been dis-
charged.
(6) Disconnect the booster cable in the reverse way of
the connection procedure.
NOTICE:
If the auxiliary battery needs to be replaced, replace it only
with a 12 V battery specially designed for the use of the
PRIUS.

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.

B04757
B04752
HV Fuse
IGCT Relay Engine Room J/B
Engine Room R/B No. 2
B04760
IN±18
± INTRODUCTIONFOR ALL OF VEHICLES
18 Author: Date:
2001 PRIUS (RM778U)

Remove the service plug with the insulated
gloves on.
If the service plug cannot be removed due to damage to the rear
portion of the vehicle, remove the HV fuse or IGCT relay
instead.
(c) Moving the damaged vehicle
HINT:
If any of the following applies, tow the vehicle away using a tow
truck lorry.

One or more of the high±voltage components and cables
is damaged.

The driving, traction, or fuel system is damaged.

The READY light is not lit when you turn ignition key to the
ON position.
NOTICE:

Before towing the vehicle away using a break down
lorry, disconnect the cable from the negative (±) ter-
minal of the auxiliary battery and remove the service
plug.
Only if none of the above applies and you see no prob-
lems that might affect the driving operation, you are
allowed to drive the vehicle away from the place of ac-
cident.

Preform the procedure below if the READY light goes
off or you detect an abnormal noise, abnormal smell,
or strong vibration while traveling:
(1) Park the vehicle in a safe place.
(2) Move the shift lever to the P position and engage
the parking brake.
(3) Disconnect the cable from the negative (±) terminal
of the auxiliary battery.
(4) Remove the service plug with insulated gloves on.

F08459
Marks
IN±22
± INTRODUCTIONFOR ALL OF VEHICLES
22 Author: Date:
2001 PRIUS (RM778U)
(3) Even in cases of a minor collision where the SRS
does not deploy, the steering wheel pad, front pas-
senger airbag assembly, side airbag assembly and
seat belt pretensioner should be inspected (See
page RS±14, RS±28, RS±63 and BO±92).
(4) Never use SRS parts from another vehicle. When
replacing parts, replace them with new parts.
(5) Before repairs, remove the airbag sensor if shocks
are likely to be applied to the sensor during repairs.
(6) Never disassemble and repair the airbag sensor as-
sembly, steering wheel pad, front passenger airbag
assembly, side airbag assembly or seat belt preten-
sioner.
(7) If the airbag sensor assembly, steering wheel pad,
front passenger airbag assembly, side airbag as-
sembly or seat belt pretensioner has been dropped,
or if there are cracks, dents or other defects in the
case, bracket or connector, replace them with new
ones.
(8) Do not directly expose the airbag sensor assembly,
steering wheel pad, front passenger airbag assem-
bly or seat belt pretensioner to hot air or flames.
(9) Use a volt/ohmmeter with high impedance (10 kW/V
minimum) for troubleshooting of the electrical cir-
cuit.
(10) Information labels are attached to the periphery of
the SRS components. Follow the instructions on the
notices.
(11) After work on the supplemental restraint system is
completed, check the SRS warning light (See page
DI±497).
(c) SPIRAL CABLE (in Combination Switch)
The steering wheel must be fitted correctly to the steering
column with the spiral cable at the neutral position, other-
wise cable disconnection and other troubles may result.
Refer to SR±14 of this manual concerning correct steer-
ing wheel installation.

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.