2001 TOYOTA PRIUS light

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 ± METER
182BE04
182BE16
U.S.A. Model
Canada Model Master Warning LightOutput Control
Warning Light
ªREADYº Light 146
METER
COMBINATION METER
1. General

The combination meter is available as a digital display type. It is located at the upper center of the instru-
ment panel to improve its visibility.

For this combination meter, a meter ECU that effects multiplex communication through the use of BEAN
(Body Electronics Area Network) has been adopted.

The display of the speedometer can be switched between km / h and MPH readings by operating the km / h-
MPH selector switch located in the middle of the center cluster. Furthermore, the odo / trip meter can be
switched between odometer and tripmeter readings by operating the odo / trip selector / reset switch located
in the middle of the center cluster.

A ªREADYº light that informs the driver that the vehicle is ready to be driven has been adopted.

A master warning light that informs the driver if an abnormality occurs in either the EMPS (Electric Motor-
assisted Power Steering), HV batteries, or the THS (TOYOTA Hybrid System) has been adopted.

An output control warning light has been adopted to show the drop of power function due to the output
drop of HV batteries.

For the purpose of making corrections in the calculation of the fuel level by the meter ECU, two inclination
sensors that detect the vehicle's longitudinal and latitudinal inclinations have been provided in the meter
ECU. In addition, an outer ambient temperature sensor has been provided in the fuel tank to detect the
temperature in the fuel tank.

BODY ELECTRICAL ± METER
182BE08
Flashes when the
ignition switch is
turned to START
Illuminates when
the vehicle is ready
to be driven
Service Tip

Inverter unit cover is left open.

HV ECU has detected a collision.149
ªREADYº Light
When the shift position is P, turning the ignition
switch to START causes the ªREADYº light to
flash and enables the vehicle to be driven. Then,
this indicator illuminates and the buzzer sounds
simultaneously.
If the indicator does not illuminate, the vehicle cannot be driven because one of the driving prohibition
conditions listed below applies.

Service plug disconnected.

Hybrid system abnormality.

Driving prohibition condition due to overload
on MG1, MG2 or inverter.
Master Warning Light
A master warning light that informs the driver if an abnormality occurs in either the EMPS, HV batteries,
or the THS has been adopted.
If an abnormality occurs in the system, the master warning light illuminates and the multi-information dis-
play shows the warning items. For details, see page 178.
Output Control Warning Light
An output control warning light has been adopted to show the drop of power function due to the output drop
of HV batteries.
This warning light comes on when the temperature of HV batteries is higher or lower than that of specified
range, or when SOC (State of Charge) is lower than the specified value with the shift position in R range.
When this warning light comes on, avoid sudden acceleration and drive carefully.

BODY ELECTRICAL ± AIR CONDITIONING 152
AIR CONDITIONING
DESCRIPTION
The air conditioning system in the Prius has the following features:
Both heating and demisting performances are realized by adopting performances are realized by adopting
the 2-way flow heater type air conditioning unit.
A multi-tank, super-slim structure evaporator has been adopted.
An automatic air conditioning system which provides enhanced air conditioning comfort according to the
occupant's senses has been adopted.
A semi-center location air conditioning unit, in which the evaporator and heater core are placed in the ve-
hicle's longitudinal direction, has been adopted.
A compact, high-performance scroll compressor with oil separator has been adopted.
The heat exchange efficiency has been improved through the adoption of the sub-cool condenser.
This condenser is integrated with the radiator to minimize the space they occupy in the engine compart-
ment.
A compact, lightweight, and highly efficient straight flow (full-path flow) aluminium heater core has been
adopted.
This heater core is integrated with a PTC (Positive Temperature Coefficient) heater, which excels in heat-
ing performance.
PTC heaters have been provided in the air duct at the footwell outlet in front of the air conditioning unit.
However, air conditioning without the PTC heaters is offered as an option on the U.S.A. models.
An electrical water pump with a bypass valve that provides a stable heater performance even if the engine
is stopped due to a function of the THS (TOYOTA Hybrid System) has been adopted.
A clean air filter that excels in removing pollen and dust is standard equipment.

BODY ELECTRICAL ± AIR CONDITIONING
152BE22152BE21New (Straight Flow)
Previous (U-turn Flow)
165BE18
PTC Heaters
Insulation Film
PTC Element
Electrode155
3) 2-Way Flow (Fresh-air / Recirculation) Mode
When all the conditions listed below are met, the external air door, internal air door, which are controlled
by the air conditioning ECU, are switched to the 2-way flow mode.
External air mode in the selected state
Blower switch in the ON state (except OFF)
Tentative air mix damper opening angle is above the specified value. (MAX HOT)
Mode select switch in either FOOT or FOOT / DEF state
Heater Core and PTC Heater
1) General
A compact, lightweight, and highly efficient straight flow (full-path flow) aluminum heater core has
been adopted.
The 2 PTC (Positive Temperature Coefficient) heaters have been built into the heater core.

BODY ELECTRICAL ± AIR CONDITIONING
165BE26165BE25
Discharge Port
Discharge Service Port
Pipe
Oil Discharge Hole
Shutter
Oil Storage Chamber
Discharge ValveRefrigerant and
Compressor OilRefrigerant
Compressor
Oil
182BE20182BE19
Flow of Coolant
Bypass Valve
Water Pump OFF
(Engine ON)Bypass Valve
Water Pump ON
(Engine OFF)Flow of Coolant163
2) Construction and Operation
The refrigerant gas that is discharged from the discharge port flows by rotating around the cylindrical
pipe in the oil separator. At this time, the centrifugal force that is created during the rotation separates
the refrigerant gas and the compressor oil due to the difference in their specific gravity. The refrigerant
gas with the lighter specific gravity passes through the inside of the pipe and travels from the discharge
service port to the outside of the compressor. The compressor oil with the heavier specific gravity is dis-
charged through the oil discharge hole in the shutter and is stored in the oil storage chamber. Then, the
compressor oil is fed again into the compressor and circulates inside the compressor.
4. Water Pump (For Air Conditioning)
An electrical water pump with a bypass valve that provides a stable heater performance even if the engine
is stopped due to a function of the THS has been adopted.
When the engine is running, this water pump ceases its operation and opens the bypass valve to minimize
the flow resistance of the coolant that is pumped by the engine water pump.