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
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
GENERAL 2000 FEATURES
172GN01
172GN02New
Previous ECMODLP
ODMSO / D OFF
Indicator
Light
O / D Switch
(Momentry
Type)O / D OFF
Indicator
LightON
OFF
O/D
SwitchON
OFF
Ignition
SwitchON
OFF
ECM
OD2O / D OFF
Indicator
Light
O / D Switch
(Lock Type)O / D OFF
Indicator
LightON
OFF
O/D
Switch
ConditionON
OFF
Real
Switch
ConditionON
OFF
Ignition
SwitchON
OFF 2
AUTOMATIC TRANSMISSION
OVERDRIVE SWITCH
The overdrive switch has been changed from the previous ON / OFF lock type to the momentary type switch.
Pressing the momentary switch closes (turns ON) the contact points, and releasing the switch opens (turns
OFF) the contact points. Accordingly, pressing the switch causes the signal to be input into the ECM.
Pressing the switch in overdrive turns OFF the overdrive. Pressing it again turns the overdrive back ON.
When the overdrive is OFF, turning the ignition switch from OFF to ON turns the overdrive back ON.
Fuel pumped up by the fuel pump, flows through the fuel filter and is distributed to each injector
at a set pressure maintained by the pressure regulator.
The fuel pressure regulator adjusts the pressure of the fuel from the fuel line (high pressure side)
to a pressure 284 kPa (2.9 kgf/cm, 41 psi) higher than the pressure inside the cylinder head, and
excess fuel is returned to the fuel tank through the return pipe.
The pulsation damper absorbs the slight fluctuations in fuel pressure caused by fuel injector from
the injector.
The injectors operate on input of injection signals from the ECM and inject fuel into the cylinder
head.
OPERATION
FUEL SYSTEM
± 5S±FE ENGINEMFI/SFI SYSTEMEG1±167
HOW TO PROCEED WITH TROUBLESHOOTING
The Engine Control System broadly consists of the sensors, Engine Control Module (ECM) and actuators.
The ECM receives signals from various sensors, judges the operating conditions and determines the
optimum injection duration, timing, ignition timing and idle speed.
In general, the Engine Control System is considered to be a very intricate system to troubleshoot. But, the
fact is that if you proceed to inspect the circuit one by one following the procedures directed in this manu-
al, troubleshooting of this system is not complex.
This section explains the most ideal method of troubleshooting and tells how to carry out the necessary
repairs.
1. CUSTOMER PROBLEM ANALYSIS
Using the customer problem analysis check sheet for reference, ask the customer in as much details
as possible about the problem.
2. CHECK AND CLEAR DIAGNOSTIC TROUBLE CODE (PRECHECK)
Before confirming the problem symptom, first check the diagnostic trouble code and make a note of
any malfunction code which is output, then clear the code.
HINT: Output of the malfunction code indicates that there is a malfunction in the circuit indicated.
However, it does not indicate whether the malfunction is still occurring or occurred in the past and
returned to normal. In order to determine this, the problem sym toms should be confirmed in step 4
first and the diagnostic trouble code be rechecked in step [6].
Accordingly, if troubleshooting is begun based on the malfunction code only in diagnostic trouble
code check in step [2], it could result in a misdiagnosis, leading to troubleshooting of circuits which
are normal and making it more difficult to locate the cause of the problem.
3. SETTING THE TEST MODE DIAGNOSIS, [4] PROBLEM SYMPTOM CONFIRMATION,
[5] SYMPTOM SIMULATION
In order to find out the trouble more quickly, set the diagnosis check in test mode and with higher
sensing ability of the ECM, confirm the problem symptoms. If the trouble does not reappear, use the
symptom simulation method to make sure the trouble is reproduced.
6. DIAGNOSTIC TROUBLE CODE CHECK IN TEST MODE
Check the diagnostic trouble code in test mode. If the malfunction code is output, proceed to step. If the
normal code is output, proceed to step [7].
7. BASIC INSPECTION
Carry out basic inspection such as the spark check and fuel pressure check, etc.
8. DIAGNOSTIC TROUBLE CODE CHART
If the malfunction code is displayed, proceed to inspect the circuit indicated by the chart for each
code.
9. MATRIX CHART OF PROBLEM SYMPTOMS
If the normal code is displayed in the diagnosis in test mode, perform troubleshooting according to
the inspection order in the Matrix Chart of Problem Symptoms.
10. PARTS INSPECTION
When the Matrix Chart of Problem Symptoms instructs to check the parts, proceed to parts inspection
section included in this manual.
11. CIRCUIT INSPECTION
Determine if the malfunction is the sensor, actuator, wire harness, connector or the ECM.
± 5S±FE ENGINEHOW TO PROCEED WITH TROUBLESHOOTINGEG1±292
Diagnosis Inspection (Test Mode)
Compared to the normal mode, the test mode has high sens±
ing ability to detect malfunctions.
It can also detect malfunctions in the starter signal circuit, the
IDL contact signal of the throttle position sensor, air condi±
tioning signal and Park/Neutral Position switch signal.
Furthermore, the same diagnostic items which are detected in
the normal mode can also be detected in the test mode.
DIAGNOSTIC TROUBLE CODE CHECK
1. Initial conditions.
(a) Battery voltage 11 V or more.
(b) Throttle valve fully closed.
(c) Transmission in neutral position.
(d) Air conditioning switched off.
2. Turn ignition switch off.
3. Using SST, connect terminals TE2 and E1 of data link
connector 1 or 2.
SST 09843±18020
4. Turn ignition switch on.
HINT:
wTo confirm that the test mode is operating, check that
the malfunction indicator lamp flashes when the igni±
tion switch is turned to ON.
wIf the malfunction indicator lamp does not flash, pro±
ceed to troubleshooting of the TE2 terminal circuit on
page EG1±430.
5. Start the engine.
6. Simulate the conditions of the malfunction described by
the customer.
7. After the road test, using SST, connect terminals TE1 and
E1 of data link connector 1 or 2.
SST 09843±18020
8. Read the diagnostic trouble code on malfunction indica±
tor lamp on the combination meter (See page EG1±297).
9. After completing the check, disconnect terminals TE1,
TE2 and E1, and turn off the display.
HINT:
wThe test mode will not start if terminals TE2 and E1 are
connected after the ignition switch is turned on.
wWhen vehicle speed is 3 mph (5 km/h) or below,
diagnostic trouble code ª42º (Vehicle speed signal) is
output, but this is not abnormal.
wWhen the engine is not cranked, diagnostic trouble
code ª43º (Starter signal) output, but this is not ab±
normal.
wWhen the automatic transmission shift lever is in the
ªDº, ª2º, ªLº or ªRº shift position, or when the air
conditioning is on or when the accelerator pedal is
depressed, code ª51º (Switch condition signal) is
output, but this is not abnormal.
± 5S±FE ENGINE DIAGNOSIS SYSTEMEG1±298
*5: This indicates items for which ª2 trip detection logicº is used. With this logic, when a logic malfunction is first detected, the
malfunction is temporarily stored in the ECM memory. If the same case is detected again during the second drive test, this
second detection causes the Malfunction Indicator Lamp to light up.
The 2 trip repeats the same mode a 2nd time. (However, the IG switch must be turned OFF between the 1st trip and 2nd
trip),
In the Test Mode, the Malfunction Indicator Lamp lights up the 1st trip a malfunction is detected.wopen in EGR gas temp. sensor circuit
wShort in VSV circuit for EGR
wEGR hose disconnected, valve stuck
wClogged EGR gas passage
wECM
wThrottle position sensor IDL circuit
wAccelerator pedal and cable
wPark/Neutral Position switch circuit
wA/C switch circuit
wECM wOpen or short in starter signal circuit
wOpen or short in ignition switch or starter relay circuit ECM
wOpen or short in knock sensor circuit
wKnock sensor (looseness).
wECMMalfunction
Indicator
Lamp*
Normal
Mode Trouble AreaMemory*
Test
ModeSee page
EG1±390EG1±385
EG1±396EG1±383
N.A.N.A.
N.A.
OFFOFF
± 5S±FE ENGINEDIAGNOSTIC TROUBLE CODE CHARTEG1±307
*: Only for California specification vehicles.
Back±Up Function
If there is trouble with the program in the ECM and the ignition signals (IGT) are not output from
microcomputer the ECM controls fuel injection and ignition timing at predetermined levels as a back±up
function to make it possible to continue to operate the vehicle.
Furthermore, the injection duration is calculated from the starting signal (STA) and the throttle position
signal (IDL). Also, the ignition timing is fixed at the initial ignition timing, 5 BTDC, without relation to
the engine speed.
HINT: If the engine is controlled by the back±up function, the malfunction indicator lamp lights up to
warn the driver of the malfunction but the diagnostic trouble code is not output.
FAIL±SAFE CHART
If any of the following codes is recorded, the ECM enters fail±safe mode.
wIgnition timing fixed at 5 BTDC.
wInjection time fixed
Starting ..... 12.1 m sec.
I D L 0 N ..... 3.3 m sec.
IDL OFF .... 6.1 m sec.
wIntake manifold vacuum is fixed at 46.7 kPa.
(350 mmHg, 13.8 inHg)
The following must each be repeated at least 2 time
consecutively.
w0.1 V VTA 0.95 V
wIDL : ON 1 IGF detected in consecutive 2 (4*) ignitions.Fail±Safe Deactivation Conditions
THW is fixed at 80C (176F).
THA is fixed at 20C (68F). Returned to normal condition.Returned to normal condition.
Returned to normal condition. Returned to normal condition. Torque control prohibited.
Max. timing retardation.Fail±Safe Operation
VTA1 is fixed at 0
.
IG switch OFF. DTC No.
Fuel cut
± 5S±FE ENGINEFAIL±SAFE CHARTEG1±308