engine overheat TOYOTA PRIUS 2001 Service Repair Manual

THS (TOYOTA HYBRID SYSTEM)27
THS CONTROL SYSTEM
1. General
The THS control system contains the following components:
HV (Hybrid Vehicle
Control) ECU
Controls the MG1, 2 and the engine according to the demand torque,
regenerative brake control and the SOC (state of charge) of HV battery. These
factors are determined by the shift position, the degree which the accelerator
is depressed, and vehicle speed.
ECM
ControlThe HV ECU receives engine status data (rpm, torque) from the ECM and
determines the engine demand torque.
Moreover, engine stop and fuel cut signals are sent according to the driving
conditions.
In addition, the vehicle speed signal received from the combination meter is
also sent.
BRAKE
ECU
ControlThe HV ECU receives data corresponding to the total braking force needed.
The HV ECU transmits the regeneration brake demand torque valve, as well
as the regeneration brake execution torque valve.
Inverter
(for MG1,
MG2)
ControlThe HV ECU sends the signal to the power transistor in the inverter for
switching the U, V, W, phase of the MG1, 2 in order to drive the MG1 and 2.
Moreover, if an overheating, overcurrent or fault voltage signal is received
from the inverter, it is shut down.
ConverterWhen a malfunction is in the Hybrid vehicle control system, the HV ECU
sends a signal to the converter, and the converter is stopped.
MG1, MG2Detects the position of the rotor of the MG1, 2 and controls the current flowing
to the MG1, 2.
In addition, the temperature is detected and the maximum load is controlled.
Battery ECUReceives the SOC of the HV battery and the current value.
Airbag Sensor
AssemblyReceives the airbag deployment signal.
A / C ECUReceives the engine power rise demand (when air-conditioning is turned ON)
and the engine running demand for water-temperature maintenance.
Accelerator Pedal
Position SensorReceives the value corresponding to degree at which the accelerator pedal is
depressed.
Shift Position SensorReceives the shift position signal (P, R, N, D, B).
Cruise Control SwitchReceives the cruise control switch signal.
Stop Light SwitchReceives the brake signal.
Interlock Switch
(for Inverter Cover and
Service Plug)Verifies that the cover of both the inverter and the service plug have been
installed.
Circuit Breaker SensorThe high-voltage circuit is intercepted if a vehicle collision has been detected.
DiagnosisWhen the HV ECU detects a malfunction, the HV ECU diagnosis and
memorizes the values corresponding to the failure.
Fail-SafeWhen the HV ECU detects a malfunction, the HV ECU stops or controls the
actuators and ECUs according to the data already stored in memory.

IN±28
± INTRODUCTIONFOR ALL OF VEHICLES
28 Author: Date:
2001 PRIUS (RM778U)
8. FOR VEHICLES EQUIPPED WITH A CATALYTIC CONVERTER
CAUTION:
If large amount of unburned gasoline flows into the converter, it may overheat and create a fire haz-
ard. To prevent this, observe the following precautions and explain them to your customer.
(a) Use only unleaded gasoline.
(b) Avoid prolonged idling.
Avoid running the engine at idle speed for more than 20 minutes.
(c) Avoid spark jump test.
(1) Perform spark jump test only when absolutely necessary. Perform this test as rapidly as possible.
(2) While testing, never race the engine.
(d) Avoid prolonged engine compression measurement.
Engine compression tests must be done as rapidly as possible.
(e) Do not run engine when fuel tank is nearly empty.
This may cause the engine to misfire and create an extra load on the converter.
(f) Avoid coasting with ignition turned off.
(g) Do not dispose of used catalyst along with parts contaminated with gasoline or oil.
9. IF VEHICLE IS EQUIPPED WITH MOBILE COMMUNICATION SYSTEM
For vehicles with mobile communication systems such as two±way radios and cellular telephones, observe
the following precautions.
(1) Install the antenna as far as possible away from the ECU and sensors of the vehicle's electronic
system.
(2) Install the antenna feeder at least 20 cm (7.87 in.) away from the ECU and sensors of the ve-
hicle's electronic systems. For details about ECU and sensors locations, refer to the section on
the applicable component.
(3) Avoid winding the antenna feeder together with other wiring as much as possible, and also avoid
running the antenna feeder parallel with other wire harnesses.
(4) Check that the antenna and feeder are correctly adjusted.
(5) Do not install powerful mobile communications system.
10. FOR USING OBD II SCAN TOOL OR TOYOTA HAND±HELD TESTER
CAUTION:
Observe the following items for safety reasons:

Before using the OBD II scan tool or TOYOTA hand±held tester, the OBD II scan tool's instruc-
tion book or TOYOTA hand±held tester's operator manual should be read thoroughly.

Be sure to route all cables securely when driving with the OBD II scan tool or TOYOTA hand±
held tester connected to the vehicle. (i.e. Keep cables away from feet, pedals, steering wheel
and shift lever.)

Two persons are required when test driving with the OBD II scan tool or TOYOTA hand±held
tester, one person to drive the vehicle and the other person to operate the OBD II scan tool or
TOYOTA hand±held tester.

± DIAGNOSTICSENGINE
DI±65
2001 PRIUS (RM778U)
DTC P0300 Random/Multiple Cylinder Misfire Detected
DTC P0301 Cylinder 1 Misfire Detected
DTC P0302 Cylinder 2 Misfire Detected
DTC P0303 Cylinder 3 Misfire Detected
DTC P0304 Cylinder 4 Misfire Detected
CIRCUIT DESCRIPTION
Misfire: The ECM uses the crankshaft position sensor and camshaft position sensor to monitor changes in
the crankshaft rotation for each cylinder.
The ECM counts the number of times the engine speed change rate indicates that misfire has occurred. And
when the misfire rate equals or exceeds the count indicating that the engine condition has deteriorated, the
MIL lights up.
If the misfire rate is high enough and the driving conditions will cause catalyst overheating, the MIL blinks
when misfiring occurs.
DTC No.DTC Detecting ConditionTrouble Area
P0300Mi fi i f d li d i d t t d d i ti l

Open or short in engine wire

Connector connection

Vacuum hose connection

I
gnition systemP0300
P0301
P0302
P0303
P0304
Misfiring of random cylinders is detected during any particular
200 or 1,000 revolutions
For any particular 200 revolutions for the engine, misfiring is
detected which can cause catalyst overheating
(This causes MIL to blink)

Ignition system

Injector

Fuel pressure

Manifold absolute pressure sensor

En
gine coolant temp. sensorP0304(This causes MIL to blink)
Engine coolant tem. sensor

Compression pressure

Valve clearance

Valve timing

ECM
HINT:

When the 2 or more codes for a misfiring cylinder are recorded repeatedly but no random misfire code
is recorded, it indicates that the misfires were detected and recorded at different times.

There is a case where the cylinder other than memorized has an accidental fire (the cylinder which is
one ahead of fired cylinder), so. at the time of checking all the checking items and if there is no ab-
normality, check the cylinder which is different from the recorded cylinder as fired.
DI6V8±03

AC2810
AC0Y9±05
AC2811
N11084
Wrong Okay
HI LO HILO
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
AC±1
1889 Author: Date:
2001 PRIUS (RM778U)
AIR CONDITIONING SYSTEM
PRECAUTION
1. DO NOT HANDLE REFRIGERANT IN AN ENCLOSED
AREA OR WEAR A NAKED FLAME
2. ALWAYS WEAR EYE PROTECTION
3. BE CAREFUL NOT TO GET LIQUID REFRIGERANT IN
YOUR EYES OR ON YOUR SKIN
If liquid refrigerant gets in your eyes or on your skin.
(a) Wash the area with lots of cool water.
CAUTION:
Do not rub your eyes or skin.
(b) Apply clean petroleum jelly to the skin.
(c) Go immediately to a physician or hospital for professional
treatment.
4. NEVER HEAT CONTAINER OR EXPOSE IT TO NAKED
FLAME
5. BE CAREFUL NOT TO DROP CONTAINER AND NOT
TO APPLY PHYSICAL SHOCKS TO IT
6. DO NOT OPERATE COMPRESSOR WITHOUT
ENOUGH REFRIGERANT IN REFRIGERATION SYS-
TEM
If there is not enough refrigerant in the refrigerant system oil lu-
brication will be insufficient and compressor burnout may occur,
so that care to avoid this, necessary care should be taken.
7. DO NOT OPEN PRESSURE MANIFOLD VALVE WHILE
COMPRESSOR IS OPERATE
If the high pressure valve is opened, refrigerant flows in the re-
verse direction and could cause the charging cylinder to rup-
ture, so open and close the only low pressure valve.
8. BE CAREFUL NOT TO OVERCHARGE SYSTEM WITH
REFRIGERANT
If refrigerant is overcharged, it causes problems such as insuffi-
cient cooling, poor fuel economy, engine overheating etc.