Page 29 of 4770

3
CAMRY ± NEW FEATURES49
8. Engine Control System
General
An engine control system based on the 5S-FE engine has been adopted. The knock sensor has been discon-
tinued because natural gas has a high octane value and is less susceptible to knocking.
The engine control system of 5S-FNE and 5S-FE engines are compared below.
System
Outline5S-FNE5S-FE
SFI
Se
quential
A D-type SFI system is used, which indirectly detects
intake air volume by manifold absolute pressure sensor.Sequential
Multiport Fuel
InjectionThe fuel injection system is a sequential multiport fuel
injection system.
Ignition timing is determined by the ECM based on
signals from various sensors.
ESA
Electronic Spark
AdvanceThe ECM corrects the ignition timing in response to
engine knocking in accordance with the signals
received from the knock sensor.
Ð
dva ce
Torque control correction during gear shifting had been
used to minimize the shift shock.*1
IAC
(Idle Air Control)A rotary solenoid type IAC valve controls the fast idle
and idle speeds.(1-Coil Type
Built-in Driver)(2-Coil Type)
Fuel Pump ControlFuel pump operation is controlled by signal from the
ECM.Ð
Fuel Cut-Off
Control
The fuel shutoff valves for the fuel tank, fuel pressure
regulator, and delivery pipe are shut off to stop the
supply of fuel when the ignition switch is turned OFF or
during abnormal conditions (such as engine stalling,
SRS airbag deployed, etc.).
Ð
Injector ControlPrevents the frozen stuck of the injector to ensure the
startability of the engine at low temperature.Ð
Oxygen Sensor
and Air Fuel Ratio
Sensor
Heater ControlMaintains the temperature of the oxygen sensor and air
fuel ratio sensor at an appropriate level to increase
accuracy of detection of the oxygen concentration in the
exhaust gas.
*2
EGR Cut-Off
ControlCuts off EGR according to the engine condition to
maintain drivability of the vehicle and durability of the
EGR components.
Evaporative
Emission ControlThe ECM controls the purge flow of evaporative
emissions (HC) in the charcoal canister in accordance
with engine conditions.
Ð
Air Conditioning
Cut-Off ControlBy turning the air conditioning compressor ON or OFF
in accordance with the engine condition, drivability is
maintained.
*3*3
Diagnosis
When the ECM detects a malfunction, the ECM
diagnoses and memorized the failed section.
DiagnosisThe diagnosis system includes a function that detects a
malfunction in the evaporative emission control system.Ð
Fail-Safe
When the ECM detects a malfunction, the ECM stops or
controls the engine according to the data already stored
in memory.
*1: Only for Automatic Transaxle Model
*
2: Air fuel ratio sensor only for California specification model
*
3: The air conditioning magnet clutch controled by the ECM
Page 30 of 4770

CAMRY ± NEW FEATURES
No.4 INJECTOR
SPARK PLUGSIGNITERS and
IGNITION COILS
No.2 INJECTOR
No.1 INJECTOR
No.3 INJECTOR
SENSORS ACTUATORS
MANIFOLD ABSOLUTE
PRESSURE SENSORSFI PIM#10+
CRANKSHAFT POSITION
SENSORNE
CAMSHAFT POSITION
SENSORG
ENGINE COOLANT TEMP.
SENSORTHW
INTAKE AIR TEMP. SENSORTHA
THROTTLE POSITION SENSORVTA
COMBINATION METER
SPD
Vehicle Speed Signal
AIR FUEL RATIO SENSOR
(Bank 1, Sensor 1)AF
HEATED OXYGEN SENSOR
(Bank 1, Sensor 2)OX2
POWER STEERING OIL
PRESSER SWITCHPSW
TAILLIGHT & REAR WINDOW
DEFOGGER SYSTEMELS
IGNITION SWITCHSTA
PARK / NEUTRAL POSITION
SWITCHNSW
STOP LIGHT SWITCHSTP
AIRBAG SENSOR ASSEMBLY
F/PS
Fuel Cut-Off Signal
#10
#20+
#20
#30+
#30
#40+
#40
ESA
IGT1,
IGT2
IGF
CONTROL VALVEIACRSD
VSV EGREGR
AIR FUEL RATIO SENSOR
HEATER AIR FUEL RATIO SENSOR
HEATER CONTROLHTAF
HEATED OXYGEN SENSOR
HEATER OXYGEN SENSOR HEATER
CONTROLHT2
MAGNET CLUTCH RERAYAIRE CONDITIONING
CUT-OFF CONTROLMGC
FUEL GAGE
LOW FUEL LEVEL WARNING
LIGHT
ECM
AIR CONDITIONING SWITCHA/C SW
R, 2, L
FUEL
FUEL W
50
Construction
The configuration of the engine control system in the 5S-FNE engine is as shown in the following chart.
(Continued)
Page 31 of 4770
3
CAMRY ± NEW FEATURES
FUEL SHUTOFF VALVE for
FUEL TANK CIRCUIT OPENING RELAY
FUEL TEMP. SENSOR for
FUEL TANKTHCNG 1
FUEL TEMP. SENSOR for
DELIVERY PIPETHCNG 2
FUEL PRESSURE SENSOR for
FUEL PIPEPCNG 1
FUEL PRESSURE SENSOR for
DELIVERY PIPEPCNG 2
DATA LINK CONNECTOR 1TE1FUEL CUT-OFF CONTROL
FC
ECM
FUEL SHUTOFF VALVE
for FUEL PRESSURE
REGULATOR
FUEL SHUTOFF VALVE for
DELIVERY PIPE
DATA LINK CONNECTOR 3
EFI MAIN RELAY BATTERY+B
VCNG 2
VCNG 3
SIL
+B1
BATT
51
Page 32 of 4770
CAMRY ± NEW FEATURES
167CN11
Intake Air
Temp. SensorSpeedometerFuel Gage & Warning
MIL
DLC3
Airbag Sensor Assembly
ECM
VSV
(for EGR)
EGR Vacuum
ModulatorIAC Valve
Throttle
Position
Sensor
Fuel Temp.
Sensor
Fuel Shutoff
ValveFuel
Pressure
Regulator
Oil
SeparatorFuel
Shutoff
Valve
Fuel
Pressure
Sensor
EGR Valve
Crankshaft Position
Sensor Manifold
Absolute
Pressure
SensorFuel Pressure
Sensor
Engine Coolant
Temp. Sensor
Camshaft
Position
Sensor
Air Fuel
Ratio Sensor
WU-TWC
Heated Oxygen Sensor
TWCManual Fuel
Shutoff
ValveFuel Filter
Fuel TankFuel Temp. Sensor
Fuel Shutoff Valve
Coupler 52
Engine Control System Diagram
Page 33 of 4770

3
CAMRY ± NEW FEATURES
172CM18
172CM19
ON
OFF1 sec 1 sec
1 sec 1 sec
ON
OFF1 sec 1 sec
2 sec 2 sec 2 sec53
Injector Control
1) General
Fuel clearing control and injector unsticking control have been added to the injector control.
2) Fuel Clearing Control
While the vehicle is being driven at speeds higher than 60 km / h (37.5 mph), and the ignition switch is
turned OFF after the ECM has detected a low temperature condition of less than 25C (77F) of intake
air temperature, the ECM closes the fuel shutoff valve for the delivery pipe. However, instead of immedi-
ately stopping the engine, the fuel clearing control allows the engine to stop on its own after the fuel in
the delivery pipe has been used up. If the engine is running even after 2 seconds or more have elapsed
after the ignition switch has been turned OFF, the EFI relay is turned OFF to stop the engine.
3) Injector Unsticking Control
When the ignition switch is turned ON after executing the fuel clearing control, the injector unsticking
control activates two cylinders at a time to unstick the valve that is frozen stuck onto the valve seat. At
low temperature conditions. At this time, the shutoff valve remains closed so that the injectors will not
inject fuel.
Gas Leak Judgment
If the ECM has detected a gas leak through the signals received from the pressure sensors, the ECM closes
the shutoff valves and flashes the low fuel level warning light.
These functions are canceled by resetting the ECM (by disconnecting the negative [-] terminal of the bat-
tery), which enables the engine to start.
(The ECM should be reset only after performing a gas leak check and making sure that the leak has been
eliminated.)
NOTE: The low fuel level warning light also flashes when the fuel level is extremely low. The flashing
patterns shown below differentiates a gas leak from a low fuel level.
Flashing Pattern
Gas Leak
Fuel Low Level
Page 39 of 4770

3
CAMRY ± NEW FEATURES
159BE05 172CM10
LCD
CE and LE Grade Model XLE Grade Model
167CN19
Front Airbag
Sensors
Airbag
Sensor
Assembly
Airbags
Seat Belt
Preten-
sioners
Fuel Cutoff
Signal
ECM Fuel Shutoff Valves59
AIR CONDITIONING
The air inlet mode selector of heater control panel has been changed from the lever type to the push button
type on the CE and LE grade models.
When the air outlet mode is set to the DEF or FOOT/DEF mode, the air inlet mode also changes to the
FRESH mode, has been also added on the CE and LE grade model.
A fully automatic controlled type air conditioning is used on the XLE grade model.
The basic construction and operation are the same as in the CAMRY SOLARA.
A defroster-linked air conditioning start up control has been continuing to use since the previous models
with air conditioning.
Heater Control Panel
SRS AIRBAG
When the SRS airbag is deployed, a signal to shut off the supply of fuel is output by the airbag sensor assembly
to the ECM for the 5S-FNE engine model.
System Diagram
Page 55 of 4770
(09248±05011) Valve Lifter Press
(09248±05021) Valve Lifter Stopper
09226±10010 Crankshaft Front & Rear Bearing
Replacer
09616±30011 Steering Worm Bearing Adjusting
Screw Wrench09224±74010 Engine Balancer Backlash
Adjusting Tool
09330±00021 Companion Flange Holding Tool09248±55020 Valve Clearance Adjust Tool Set
RECOMMENDED TOOLS
09816±30010 Oil Pressure Switch Socket09278±54012 Drive Shaft Holding Tool09249±63010 Torque Wrench Adaptor
09843±18020 Diagnosis Check Wire
09090±04010 Engine Sling Device
09200±00010 Engine Adjust KitCamshaft timing pulley
For suspension engineCrankshaft pulley
Oil pump pulley
Knock sensor
± 5S±FE ENGINEENGINE MECHANICALEG1±5
Page 72 of 4770

Troubleshooting
If the CO/HC concentration does not comply with
regulations, perform troubleshooting in the order
given below.
(a) Check oxygen sensor operation.
(See page EG1±231)
(b) See the table below for possible causes, then inspect
and correct the applicable causes if necessary.
1. Faulty ignitions:
wIncorrect timing
wFouled, shorted or improperly gapped plugs
wOpen or crossed high±tension cords
wCracked distributor cap
2. Incorrect valve clearance
3. Leaky EGR valve
4. Leaky intake and exhaust valves
5. Leaky cylinder
1. Restricted air filter
2. Faulty MFI/SFI systems
wFaulty pressure regulator
wClogged fuel return line
wDefective engine coolant temp. sensor
wDefective intake air temp. sensor
wFaulty ECM
wFaulty injector
wFaulty throttle position sensor
wMAP sensor 1. Vacuum leaks:
wPCV hose
wEGR valve
wIntake manifold
wThrottle body
w!AC valve
wBrake booster line
2. Lean mixture causing misfire
Rough idle
(Black smoke from exhaust) Rough idle
(Fluctuating HC reading) Rough idleProblems
Causes
Normal
High High High
HighLow
± 5S±FE ENGINEENGINE MECHANICALEG1±22