2001 TOYOTA PRIUS air conditioning

BODY ELECTRICAL ± AIR CONDITIONING
174BE08
Ex-HI
Blower
Air
Volume
LO
0
Time (a) (b) (c)
Sec.
174BE09
Ex-HI
Blower
Air
Volume
LO
0
Time(a) (b) Sec.169
c. Time-Lagged Air Flow Control
2 types of time-lagged air flow control (in accordance with the temperature detected by the evaporator
temperature sensor) help prevent hot air from being emitted from FACE or BI-LEVEL vent.
i) Evaporator temperature sensor at specified temperature or more
As shown in the diagram on the right, this
control turns OFF the blower motor for
approximately specified time (a) and turns
ON the compressor to cool the air condi-
tioning unit.
After approximately specified time (a)
have elapsed, the blower motor rotates in
the manual LO mode, allowing the cooled
air to be discharged from the vents. Thus,
the discomfort that is associated with the
discharge of warm air is prevented.
Between approximately specified time (b)
to (c), the airflow volume according to the
timelagged airflow control and the airflow
volume of the blower control according to
the calculation of the required outlet air
temperature are compared. The airflow
volume is then regulated at the smaller vol-
ume of the two.
After specified time (c) have elapsed, con-
trol is effected by the blower control ac-
cording to the calculation of the required
outlet air temperature.
ii) Evaporator temperature sensor at specified temperature or less
As shown in the diagram on the right, for
approximately specified time (a), the blow-
er motor rotates in the manual LO mode.
Thereafter, up to approximately specified
time (b), the airflow volume according to
the time-lagged airflow control and the air-
flow volume according to the blower con-
trol of the calculation of the required outlet
air temperature are compared. The airflow
volume is then regulated at the smaller vol-
ume of the two.
After specified time (b) have elapsed, con-
trol is effected based on the blower control
according to the calculation of the required
outlet air temperature.

BODY ELECTRICAL ± AIR CONDITIONING
182BE51
Hi
Lo Blower
Air
Volume
Small Large
Amount of Sunligt
182BE28182BE29
1
0
Small Large
Vehicle Speed Fresh Air
Recirculation
182BE52
Outlet Air
Half
Inlet Air
Low High
TAO (Temperature Air Outlet) 170
d. Sunlight Air Flow Control
Controls the blower speed in accordance
with the intensity of the sunlight when the air
outlet mode is at FACE or BI-LEVEL. The
blower low speed can be adjusted up to 4
steps, in response to the sunlight signal re-
ceived from the solar sensor.
2-Way Flow Mode Control
At the time of selecting FRESH mode, air conditioning ECU will judge it as 2-way flow mode when the
blower outlet is selected to FOOT or FOOT / DEF, the tentative air mix damper opening angle is above the
specified valve (MAX HOT), and either the blower volume is more than the specified volume or the vehicle
speed is less than the specified speed.
Half Inlet Air Mode Control
At the time of selecting FRESH mode, air condi-
tioning ECU will judge it as half inlet air mode
when the blower outlet mode is selected to FACE
or BI-LEVEL and TAO (Temperature Air Out-
let) is more than the specified temperature, and
operates both outlet air introduction and inlet air
circulation at the same time.

BODY ELECTRICAL ± AIR CONDITIONING
182BE31
Tentative Damper Opening Angle
(During 2-Way Flow Mode)
Damper
Opening
Recirculation /
Fresh Air
SwitchingFresh
Air
2-Way
Flow
MAX HOT
182BE33
A / C SwitchMAX
Switch171
Air Inlet Control System
1) Manual Control
Drives the air inlet servomotor according to
the operation of the air inlet control switch and
fixes the dampers in the FRESH or RECIRC
position.
The 2-way flow mode control switches the re-
circulation / fresh-air function in accordance
with the opening of the air mix damper, calcu-
lates the target opening of the damper, and ro-
tates the servomotor.
2) Battery ECU Forced Fresh Air Mode
When the air conditioning ECU receives the forced fresh air mode signal from the battery ECU via the
HV ECU and the ECM, the damper forcefully switches to the FRESH mode.
3) DEF, FOOT / DEF Mode Control
When the mode switching switch is switched to FOOT / DEF mode from DEF mode or other than
FOOT / DEF mode, air conditioning ECU switches to FRESH mode forcibly.
Also, when the mode switching switch is switched to DEF mode from other than DEF mode, air condi-
tioning ECU turns MAX mode ON and switched to FRESH mode forcibly.
Compressor Control System
1) OFF Control
Turns OFF the magnetic clutch of the compressor when the conditions for turning the blower motor OFF
during warm-up control have been met.
2) Compressor Lock Judgment
When the magnetic clutch is ON, if the air
conditioning ECU judges that the compressor
has been locked, it turns OFF the magnetic
clutch relay and flashes the indicator lamp in
the A / C or MAX switch. The conditions in
which the ECU judges the compressor to have
locked are when a slippage rate of 80% or
more has been continued for 3 seconds or
more.

BODY ELECTRICAL ± AIR CONDITIONING 172
3) Refrigerant Pressure Malfunction Detection
By monitoring the pressure switch signal, this system can judge the refrigerant pressure to be abnormal,
and turns off the compressor magnetic clutch relay, if the pressure switch remains off.
4) MAX Switch ON Control
a. General
In case of usual air conditioning operation, the air conditioning system shows superior control on cool-
ing performance and fuel efficiency by combining the engine ON / OFF control by the hybrid control
and the air conditioning ON / OFF control.
In this MAX switch ON control, it controls by attaching greater importance to cooling performance of
the air conditioning.

IN05Y±22
± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN±29
29 Author: Date:
2001 PRIUS (RM778U)
HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
GENERAL INFORMATION
A large number of ECU controlled systems are used in the PRIUS. In general, the ECU controlled system
is considered to be a very intricate system requiring a high level of technical knowledge and expert skill to
troubleshoot. However, the fact is that if you proceed to inspect the circuits one by one, troubleshooting of
these systems is not complex. If you have adequate understanding of the system and a basic knowledge
of electricity, accurate diagnosis and necessary repair can be performed to locate and fix the problem. This
manual is designed through emphasis of the above standpoint to help service technicians perform accurate
and effective troubleshooting, and is compiled for the following major ECU controlled systems:
The troubleshooting procedure and how to make use of it are described on the following pages.
SystemPage
6. EngineDI±1
7. Hybrid Vehicle Control SystemDI±174
8. HV Battery Control SystemDI±312
9. Anti±Lock Brake System With EBD & RBSDI±351
10.Electric Motor Power SteeringDI±452
11. Supplemental Restraint SystemDI±495
12.Cruise Control SystemDI±640
13.Combination Meter SystemDI±662
14.Body Control SystemDI±678
15.Driver Door Control SystemDI±730
16.Multiplex Communication SystemDI±750
17.Navigation SystemDI±789
18.Air Conditioning SystemDI±864
FOR USING OBD II SCAN TOOL OR TOYOTA HAND±HELD TESTER

Before using the scan tool or tester, the scan tool's instruction book or tester's operator manual should
be read thoroughly.

If the scan tool or tester cannot communicate with ECU controlled systems when you have connected
the cable of the scan tool or tester to DLC3, turned the ignition switch ON and operated the scan tool,
there is a problem on the vehicle side or tool side.
(1) If communication is normal when the tool is connected to another vehicle, inspect the diagnosis
data link line (Bus
line) or ECU power circuit of the vehicle.
(2) If communication is still not possible when the tool is connected to another vehicle, the problem
is probably in the tool itself, so perform the Self Test procedures outline in the Tester Operator's
Manual.

IN±32± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
2001 PRIUS (RM778U)
2. SYMPTOM CONFIRMATION AND DIAGNOSTIC TROUBLE CODE CHECK
The diagnostic system in the PRIUS fulfills various functions. The first function is the Diagnostic Trouble
Code Check in which a malfunction in the signal circuits to the ECU is stored in code in the ECU memory
at the time of occurrence, to be output by the technician during troubleshooting. Another function is the Input
Signal Check which checks if the signals from various switches are sent to the ECU correctly.
By using these check functions, the problem areas can be narrowed down quickly and troubleshooting can
be performed effectively. Diagnostic functions are incorporated in the following systems in the PRIUS.
SystemDiagnostic Trouble
Code CheckInput Signal Check
(Sensor Check)Diagnostic Test
Mode (Active Test)
Engine (with Check
Mode)
Hybrid Vehicle Control System
HV Battery Control System (with Check
Mode)
Anti±Lock Brake System With EBD & RBS
Electric Motor Power Steering
Supplemental Restraint System
Cruise Control System
Multiplex Communication System
Navigation System
Air Conditioning System

IN0CI±02
± INTRODUCTIONTERMS
IN±51
2001 PRIUS (RM778U)
GLOSSARY OF SAE AND TOYOTA TERMS
This glossary lists all SAE±J1930 terms and abbreviations used in this manual in compliance with SAE rec-
ommendations, as well as their TOYOTA equivalents.
SAE
ABBREVIATIONSSAE TERMSTOYOTA TERMS
( )±±ABBREVIATIONS
A/CAir ConditioningAir Conditioner
ACLAir CleanerAir Cleaner, A/CL
AIRSecondary Air InjectionAir Injection (AI)
APAccelerator Pedal±
B+Battery Positive Voltage+B, Battery Voltage
BAROBarometric PressureHAC
CACCharge Air CoolerIntercooler
CARBCarburetorCarburetor
CFIContinuous Fuel Injection±
CKPCrankshaft PositionCrank Angle
CLClosed LoopClosed Loop
CMPCamshaft PositionCam Angle
CPPClutch Pedal Position±
CTOXContinuous Trap Oxidizer±
CTPClosed Throttle PositionLL ON, Idle ON
DFIDirect Fuel Injection (Diesel)Direct Injection (DI)
DIDistributor Ignition±
DLC1
DLC2
DLC3Data Link Connector 1
Data Link Connector 2
Data Link Connector 31: Check Connector
2: Total Diagnosis Comunication Link (TDCL)
3: OBD II Diagnostic Connector
DTCDiagnostic Trouble CodeDiagnostic Code
DTMDiagnostic Test Mode±
ECLEngine Control Level±
ECMEngine Control ModuleEngine ECU (Electronic Control Unit)
ECTEngine Coolant TemperatureCoolant Temperature, Water Temperature (THW)
EEPROMElectrically Erasable Programmable Read Only Memory
Electrically Erasable Programmable Read Only Memory
(EEPROM),
Erasable Programmable Read Only Memory (EPROM)
EFEEarly Fuel EvaporationCold Mixture Heater (CMH), Heat Control Valve (HCV)
EGRExhaust Gas RecirculationExhaust Gas Recirculation (EGR)
EIElectronic IgnitionTOYOTA Distributorless Ignition (TDI)
EMEngine ModificationEngine Modification (EM)
EPROMErasable Programmable Read Only MemoryProgrammable Read Only Memory (PROM)
EVAPEvaporative EmissionEvaporative Emission Control (EVAP)
FCFan Control±
FEEPROMFlash Electrically Erasable Programmable
Read Only Memory±
FEPROMFlash Erasable Programmable Read Only Memory±
FFFlexible Fuel±
FPFuel PumpFuel Pump
GENGeneratorAlternator
GNDGroundGround (GND)

PP3AD±01
± PREPARATIONAIR CONDITIONING
PP±57
11 8 Author: Date:
2001 PRIUS (RM778U)
AIR CONDITIONING
SST (Special Service Tools)
07110±58060Air Conditioner Service Tool Set
(07117±78050)Refrigerant Charging Gauge
(07117±88060)Refrigerant Charging HoseDischarge (Red)
(07117±88070)Refrigerant Charging HoseSuction (Blue)
(07117±88080)Refrigerant Charging HoseUtility (Green)
(07117±58060)Refrigerant Drain Service Valve
(07117±58080)Quick Disconnect AdapterDischarge (diam. 16 mm)
(07117±58090)Quick Disconnect AdapterSuction (diam. 13 mm)
(07117±58070)T±Joint
07116±38360Gas Leak Detector Assembly
07112±76050Magnetic Clutch Stopper
07112±66040Magnetic Clutch Remover