2001 TOYOTA PRIUS open gas tank

ENGINE ± 1NZ-FXE ENGINE62
ENGINE CONTROL SYSTEM
1. General
The engine control system for the 1NZ-FXE engine has following system.
System
Outline
SFI
Sequential Multiport
Fuel InjectionAn L-type SFI system directly detects the intake air volume with a hot-wire
type mass air flow meter.
ESA
Electronic Spark
AdvanceIgnition timing is determined by the ECM based on signals from various
sensors. The ECM corrects ignition timing in response to engine knocking.
VVT-i
Variable Valve
Timing-intelligentControls the intake camshaft to an optimal valve timing in accordance with
the engine condition.
ETCS-i
Electronic
Throttle Control
System-intelligentOptimally controls the throttle valve opening in accordance with the ECM,
and the conditions of the engine and the vehicle, and comprehensively
controls the ISC and cruise control system.
Fuel Pump Control
Fuel pump operation is controlled by signal from the ECM.

To stop the fuel pump during operation of the SRS airbag.
Oxygen Sensor Heater
ControlMaintains the temperature of the oxygen sensors at an appropriate level to
increase accuracy of detection of the oxygen concentration in the exhaust gas.
Evaporative Emission
Control

The ECM controls the purge flow of evaporative emissions (HC) in the
charcoal canister in accordance with engine conditions.

Using 3 VSVs and a vapor pressure sensor, the ECM detects any
evaporative emission leakage occurring between the fuel tank and the
charcoal canister, and vapor reducing fuel tank through the changes in the
tank pressure. For details, see page 79.
Toyota HCAC System
The ECM controls the VSV (for Toyota HCAC System) to improve the clean
emission performance of the exhaust gas when the temperature of the TWC
is low. For details, see page 58.
Air Conditioning
Cut-Off ControlBy turning the air conditioning compressor OFF in accordance with the
engine condition, drivability is maintained.
Cooling Fan ControlRadiator cooling fan operation is controlled by signals from ECM based on
the engine coolant temperature sensor signal (THW).
HV Immobiliser
Prohibits fuel delivery, ignition, and starting the HV system if an attempt is
made to start the HV system with an invalid ignition key. For details, see page
80.
DiagnosisWhen the ECM detects a malfunction, the ECM diagnoses and memorizes
the failed section.
Fail-SafeWhen the ECM detects a malfunction, the ECM stops or controls the engine
according to the data already stored in memory.

ENGINE ± 1NZ-FXE ENGINE 78
Operation
Initially, the VSV (for canister closed valve) is closed, and the VSV (for EVAP) is open, enabling the VSV
(for purge flow switching valve) to keep the passage between the charcoal canister and the purge line open.
This causes a vacuum to be applied to the purge line, evaporator line, recirculation line, and the line from
the charcoal canister to the fuel tank.
Next, the VSV (for EVAP) is closed in order to maintain a vacuum from the VSV (for EVAP) to the inside
of the fuel tank. Then, any subsequent changes in the pressure are monitored by the vapor pressure sensor
in order to check for evaporative emission leaks.
Next, the VSV (for canister closed valve) and the VSV (for EVAP) open, enabling the VSV (for purge flow
switching valve) to keep the passage between the fuel tank and the purge line open. Then, the air in the fuel
tank is drawn in by the vacuum of the intake chamber, and the density of HC in the exhaust gases is measured
by the oxygen sensor to detect any leaks.
If a leak is detected, the malfunction indicator lamp (MIL) illuminates to inform the driver. Also, the diag-
nostic trouble code (DTC) can be accessed through the use of a hand-held tester.
For details on the DTCs, refer to the 2001 Prius Repair Manual (Pub. No.RM778U).
10. HV Immobiliser System
The HV immobiliser system has been designed to prevent the vehicle from being stolen. This system uses
a HV ECU that stores the ID code of the authorized ignition key. If an attempt is made to start the HV system
using an unauthorized key, the HV ECU prohibit fuel delivery, ignition, and starting the HD system effective-
ly disabling the engine.
For details see page 184 in the HV Immobiliser System section.
11. Diagnosis System
The diagnostic trouble codes can be output via DLC3 to an OBD-II scan tool or a hand-held tester. For details,
refer to the 2001 Prius Repair Manual (Pub. No.RM778U).

DI±16
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)P0340
(DI±76)
Camshaft Position Sensor Cir-
cuit Malfunction
Open or short in camshaft position sensor circuit
Camshaft position sensor
Camshaft timing pulley
ECM

P0420
(DI±78)Catalyst System Efficiency Be-
low Threshold (Bank 1)
Gas leakage on exhaust system
Open or short in heated oxygen sensor circuit
Heated oxygen sensor
Three±way catalytic converter

P0440
(DI±81)Evaporative Emission Control
System Malfunction
Hose or tube cracked, hole, damaged or loose seal
Fuel tank cap incorrectly installed
Fuel tank cap cracked or damaged
Vacuum hose cracked, hole, blocked,damaged or discon-
nected
Fuel tank cracked, hole or damaged
Charcoal canister cracked, hole or damaged
Open or short in vapor pressure sensor circuit
Vapor pressure sensor
Fuel tank over fill check valve cracked or damaged
ECM

P0441
(DI±87)Evaporative Emission Control
System Incorrect Purge Flow
Vacuum hose cracked, hole, blocked damaged or discon-
nected
Open or short in vapor pressure sensor circuit
Vapor pressure sensor
Open or short in VSV circuit for EVAP
VSV for EVAP
P0446
(DI±87)Evaporative Emission Control
System Vent Control Malfunction
VSV for EVAP
Open or short in VSV circuit for vapor pressure sensor
VSV for vapor pressure sensor
Charcoal canister cracked, hole or damaged
Fuel tank over fill check valve cracked or damaged
ECM
P0450
(DI±103)Evaporative Emission Control
System Pressure Sensor Mal-
function
Open or short in vapor pressure sensor circuit
V
P0451
(DI±103)Evaporative Emission Control
System Pressure Sensor Range/
PerformanceVapor pressure sensor
ECM
P0500
(DI±105)Vehicle Speed Sensor Malfunc-
tion
Combination meter
Open or short in vehicle speed sensor circuit
Vehicle speed sensor
ECM

P0505
(DI±107)Idle Control System MalfunctionErectric throttle control system
Air induction system
*1: 


MIL lights up

B00417
SST
B11832
Fuel Pump
Connector
B00679
Vinyl Bag
SF±2
± SFISFI SYSTEM
1216 Author: Date:
2001 PRIUS (RM778U)
(b) When installing the battery, be especially careful not to in-
correctly connect the positive (+) and negative (±) cables.
(c) Do not permit parts to receive a severe impact during re-
moval or installation. Handle all SFI parts carefully, espe-
cially the ECM.
(d) Be careful during troubleshooting as there are numerous
transistor circuit, and even slight terminal contact can
cause further troubles.
(e) Do not open the ECM cover.
(f) When inspecting during rainy weather, take care to pre-
vent entry of water. Also, when washing the engine
compartment, prevent water from getting on the SFI parts
and wiring connectors.
(g) Parts should be replaced as an assembly.
(h) Care should be taken when pulling out and inserting wir-
ing connectors.
(1) Release the lock and pull out the connector, pulling
on the connectors.
(2) Fully insert the connector and check that it is locked.
(i) Use SST for inspection or test of the injector or its wiring
connector.
SST 09842±30080
7. FUEL SYSTEM
(a) When disconnecting the high fuel pressure line, a large
amount of gasoline will spill out, so observe these proce-
dures.
(1) Disconnect the fuel pump connector.
(2) Start the engine. After the engine has stopped on
its own, turn the ignition switch to LOCK.
(3) Disconnect the fuel tube from the fuel tank.
(4) Drain the fuel remained inside the fuel tube.
(5) Prevent the disconnected fuel tube from damaging
and mixing foreign objects by covering them with a
vinyl bag.