lights TOYOTA PRIUS 2001 Service User Guide

CHASSIS ± BRAKES105
4. Function of Main Components
ComponentsFunction
ABS Warning
LightLights up to alert the driver when the brake ECU detects the
malfunction in the ABS.
Combination
Meter
Brake System

Lights up together with the ABS warning light to alert the driver
when the brake ECU detects the malfunction not only in the ABS
but also in the EBD controlBrake System
Warning Lightbut also in the EBD control.

Lights up to alert the driver when the malfunction occurs in the
brake system.
Stop Light SwitchDetects the brake depressing signal.
Brake Warning BuzzerEmits a continuous sound to inform the driver that the ABS ECU
detects the malfunction in the hydraulic brake booster.
Speed SensorsDetect the wheel speed of each of the four wheels.
Brake ECU

Processes various sensor signals, regenerative brake signals, to
execute control of the ABS control, EBD control, regenerative
coordination control and hydraulic brake booster.

Communicates control data with the HV ECU.
HV ECUMaintains serial communication with the brake ECU to exchange
regenerative coordination control signals.
Hydraulic Brake Booster
Assists with the pedal effort applied to the brake pedal.

Supplies hydraulic pressure.
Brake ActuatorControls the brake fluid pressure to each brake wheel cylinder by
signals from the brake ECU.
Solenoid RelaySupplies power to the ABS's solenoid valve's in the brake actuator.
Pump Motor RelaysControl the pump motor operation in the hydraulic brake booster.

CHASSIS ± STEERING
182CH95
182CH76
Twist Angle
Basic Position
Cornering
Torque
[V]
Voltage
Voltage difference between
outputs 1 and 2 during
straight line driving (0)
Torque Sensor 2
Torque Sensor 1
0 ±+
Right Turn Left Turn127
ii) Steering to the right
When the driver turns the steering to the
right, the steering torque is transmitted to
the pinion shaft's input shaft, causing the
input shaft to rotate. Because the reaction
force of the ground surface acts on the rack
bar, the torsion bar that links the input shaft
and the pinion twists until a torque that
equalizes with the reaction force is gener-
ated. Thus, a relative displacement is
created between the resistor that is secured
onto the input shaft and the contact that is
secured onto the pinion shaft's output shaft.
As a result, the resistance changes, causing
the torque sensor's outputs 1 and 2 to
change as shown in the right diagram. The
EMPS ECU uses this voltage difference to
calculate the power assist torque to drive
the DC motor, thus generating a power as-
sist force in the pinion shaft via the reduc-
tion mechanism.
iii) Steering Hold Condition
The torsion bar shift to a position in which the sum of the driver's steering torque and the motor's assist
torque equalizes with the reaction force of the ground surface in order to maintain the steering holding
condition.
EMPS ECU
1) EMPS Control
The EMPS ECU receives signals from various sensors, judges the current vehicle condition, and deter-
mines the assist ampere to be applied to the DC motor accordingly.
2) Self-Diagnosis
If the EMPS ECU detects a malfunction in the EMPS system, the warning light that corresponds to the
function in which the malfunction has been detected lights up to alert the driver of the malfunction.
The EMPS ECU will also store the codes of the malfunctions. The DTCs (Diagnostic Trouble Codes)
can be accessed through the use of a hand-held tester. For details, see the 2001 Prius Repair Manual (Pub.
No. RM778U).
3) Fail-Safe
If the EMPS ECU detects a malfunction in the EMPS system, the system basically turns OFF the power
to prohibit power assist. As a result, the EMPS system operates the same way as manual steering.
However, depending on the location in which the malfunction occurred, power assist may be provided
by reducing the power assist amperage or by fixing the amount of power assist without relying on the
vehicle speed.

BODY ELECTRICAL ± MULTIPLEX COMMUNICATION SYSTEM 142
SYSTEM OPERATION
1. General
The ECUs that pertain to the body electrical system perform the functions and system controls described be-
low.
Gateway ECU
Conversion of data between AVC-LAN and BEAN
Transmission of vehicle information to the display ECU, in order for it to be displayed on multi-informa-
tion display
Body ECU
Power window system control (Front, Rear passenger only)
Door lock control system control
Wireless door lock remote control system control
Theft deferrent system control
Daytime running light system control
Illuminated entry system control
Light auto turn-off system control
Seat belt warning system control
Key reminder system control
Diagnosis
Meter ECU
Meter control
Illumination and flashing control of indicator and warning lights
Sounding control of warning buzzer
Air Conditioning ECU
Air Conditioning control
ECM
Engine control
Diagnosis
Display ECU
Transmission and reception associated with audio and visual functions

BODY ELECTRICAL ± LIGHTING
151LBE68151LBE67
Multi-Reflector Type HeadlightConventional Headlight Reflector
(Multiple Parabolic Shape)
Headlight Bulb
Headlight Bulb
Lens
Light DistributionReflector
(Rotating Parabolic Shape)
Headlight Bulb
Lens Cut
Lens
Light Distribution
182BE03
From
BatteryDimmer Relay
Headlight
Relay
Parking
Brake Switch
H-LP DIM
PKBDaytime
Running
Light Relay
DRL
From
BatteryEH
HILO HI
LO
No.4
Daytime
Running
Light Relay
144
LIGHTING
HEADLIGHTS
The prius has newly adopted the multi-reflector headlights. Conventional headlights accomplish the dispersion
and distribution of the light that is emitted by the bulbs through the lens cut pattern. However, with the multi-reflec-
tor type headlights, the light from the bulbs is dispersed and distributed through multiple parabolic shaped reflec-
tors. As a result, the lens cut pattern is no longer provided in the center of the lens, thus realizing a clear look.

Light Distribution Diagram 
DAYTIME RUNNING LIGHT SYSTEM
The daytime running light system is adopted for Canada model as standard and U.S.A. model as optional
equipment. This system is designed to automatically activate the headlights (dimmed low beams) during the
daytime to keep the car highly visible to other vehicles.
This system is controlled by a semi-conductor relay circuit (daytime running light relay).

BODY ELECTRICAL ± LIGHTING145
ILLUMINATED ENTRY SYSTEM
When a door is unlocked through a key operation or transmitter operation, or if a door is opened or closed,
the illuminated entry system turns ON the dome light. If the ignition switch is turned to the ACC or ON
position or if all doors are locked during the 15 seconds in which this light are ON, they will immediately
turn OFF.
This system is controlled by the body ECU.
LIGHT AUTO TURN-OFF SYSTEM
When the ignition key is turned from ON or ACC to LOCK position and the driver's door is opened with
the taillights and headlights on, this system automatically turns them off.
This system is controlled by the body ECU.

BODY ELECTRICAL ± ACCESSORIES 176
1) Map Screen
The map screen is a function that is provided in the GPS voice navigation system.
Based on the map data on the DVD, signals from the GPS satellites, signals from the built-in gyro sensor,
and signals from the vehicle's speed sensor, the vehicle's present position, direction of travel, and driven
distance are calculated and displayed on this screen. This screen has the display functions listed below.
Item
Outline
Heading Up / North UpChanges the orientation of the map.
Front WideDisplays a map in the direction of travel of the vehicle in
an enlarged form.
Stepless Scale DisplayChanges the scale of the map from the basic 11 steps to
an even finer display.
Direct Scale ChangeDirectly select and display the map scale.
Multi-step Scale DisplayChange and display the map scale in 11 stages.
Map DisplayScroll DisplayScrolls the screen to display the desired point on the map.Map Display
Split-view DisplayDisplays different modes on a screen that is split into two
views.
Points-of-Interest
DisplayDisplays selected types of marks on the map.
Taillight-interlocked
Map Color ChangeChanges the displayed color on the map screen when the
taillights are turned ON.
Road Number Sign
Board DisplayDisplays the road numbers on the map.
Hybrid Points-of-interest
SearchNarrows the search by names of the points-of-interest,
category, and areas.
Points-of-interest
Pinpoint DisplayPinpoints and displays the position of the point-of-
interest.
House Number SearchSearches for a house number.
Special Memory PointSets a pre-registered point as a destination point while
driving.
Destination
SearchNearest Points-of-
Interest Search List
Display
Searches nearest points-of-interest and displays a list.
Intersection SearchBy specifying two streets, the point at which they
intersect is set as the destination point.
Emergency SearchPerforms a specific search for hospitals, police stations,
and dealers.
Freeway Entrance / Exit
SearchSearches for the destination by the name of the street that
connects to a freeway entrance / exit.
Route SearchSearches for multiple routes.
Search
Search Condition
DesignationSearches for the recommended, shortest, and other
routes.
SearchRegulated Road
ConsiderationPerforms search while considering regulated roads.
Avoidance AreaAvoids a designated area and searches a route.
(Continued)

BODY ELECTRICAL ± ACCESSORIES
182BE41
RRP DBody
ECUUARTPower
Window
Master
SwitchDoor Control
Switch (Manual)
Door Control
Switch (Key-linked)
169BE10
Key Unlock
Warning SwitchDoor Courtesy
Switch
Door Lock
MotorsBody
ECU
Serial Data Link
Wireless Door
Control Receiver
Horn
RelayHeadlight
RelayTaillight
RelayTransmitter183
DOOR LOCK CONTROL SYSTEM
The door lock control system has the following features:
This system has a ªkey-linked lock and unlockº, ªkey-confine preventionº and ªmanual unlock prohibi-
tionº functions.
A 2-step unlock function is provided to unlock the driver's door by turning the key cylinder first and to
unlock passenger's door by turning it the second time.
The control of this system is effected by the body ECU. The door lock control signal from the driver's door
is transmitted from the power window master switch to the body ECU through the UART (Universal
Asynchronous Receiver Transmitter).
If you unlock using the ignition key from the conditions in which all the doors are locked, the dome light
will be lighted.

System Diagram 
WIRELESS DOOR LOCK REMOTE CONTROL SYSTEM
The wireless door lock remote control system has the following features:
In this system, the wireless door control receiver performs the code identification process and the body
ECU effects the door lock control. Serial data link is provided for communication between the wireless
door control receiver and the body ECU.
A key-holder type transmitter has been adopted, and it contains the following three switches: the door lock
switch, door unlock switch, and panic switch.
A rolling code system, in which the signal configuration changes each time when a signal is transmitted
by the transmitter, has been adopted.
Panic alarm operation has been adopted.
The verification light function has been adopted. When the transmitter is used to lock or unlock the doors,
this function flashes the taillights to inform that the operation has been completed. However, at the time
of unlocking, the dome light will be lighted.

BODY ELECTRICAL ± ACCESSORIES
182BE43
DKUL
DKL
LSWD
Power
Window
Master
Switch
Ignition Key SW
From
BatteryIG
LSWP
LSR
KSW
DCTY
PCTY
RCTY
LCTY
HCTY
LUG
Courtesy
Switches
PKL
PKUL
Door Lock Motors
RRP D
Body
ECU
From Battery
Headlight
RelayTaillight
RelayHorn
Relay
HRLY
TRLYTo
HeadlightTo
Taillight
To
Vehicles
Horn
HR
From Battery
Interior
Light
Interior
Light
Relay
Security
Horn
Wireless
Door Control
Receiver
MPX
INDECM
Security
Indicator
185
THEFT DETERRENT SYSTEM
1. General
The theft deterrent system uses the door lock control system components and some other parts. When
somebody attempts to forcibly enter the vehicle or open the engine hood or luggage compartment door
without a key, or when the battery terminals are removed and reconnected, the theft deterrent system
sounds the vehicle's horn, security horn and flashes the headlights, taillights, hazard lights and interior
light for about one minute to alert. At the same time, it locks all the doors.
The control of this system is effected by the body ECU.

Wiring Diagram 

BODY ELECTRICAL ± ACCESSORIES187
Condition (2)
When the doors, engine hood, and luggage compartment door are all closed and locked, and 30 seconds
have elapsed.
Condition (3)
When one of the doors, engine hood, or luggage compartment door is changed from ªcloseº to ªopenº.
When one of the doors, engine hood, or luggage compartment door is changed from ªlockº to ªunlockº.
When the ignition key is inserted in the ignition key cylinder.
When a terminal is disconnected from the battery and re-connected.
Alert State: a state in which attempted theft can be detected
The system transfers to the alarm state if any one of the conditions (4) listed below is met, or to the non-alert
state if any one of the conditions (5) is met.
Condition (4)
Any door, engine hood, or luggage compartment door is opened.
The ignition key or the wireless door lock remote control system other than the transmitter is used for
unlocking.
The luggage compartment door is opened with something other than the ignition key.
The engine hood is opened.
A terminal is disconnected from the battery and re-connected.
The wiring harness is directly connected as if to turn the ignition switch ON.
Condition (5)
The ignition key is used to unlock the doors or the luggage compartment door.
The transmitter of the wireless door lock remote control system is used to unlock the doors.
The ignition key is inserted in the ignition key cylinder and turned until the ignition switch is ON.
Alarm State: a state in which attempted theft can be detected
When an attempted theft is detected, the system sounds the vehicle's horn and the security horn, flashes
the headlights, taillights, and hazard lights, and illuminates the interior light to alert the people in the area.
If any one of the doors is unlocked, and the ignition key is not inserted in the ignition key cylinder, the
system forcefully locks the doors once.
The system transfers to the alert state if the condition (6) described below is met, or, when the system is
in the alarm state, it transfers to the non-alert state if any one of the conditions (5) described above is met.
At this time, the taillights are illuminated for 2 seconds to inform the driver that an attempted theft has been
detected.
Condition (6)
After approximately 60 seconds of the alarm time have elapsed.

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.