1999 TOYOTA CAMRY light

DI±272
± DIAGNOSTICSENGINE (1MZ±FE)
507 Author: Date:
DTC P0171 System too Lean (Fuel Trim)
(Except California Spec.)
DTC P0172 System too Rich (Fuel Trim)
(Except California Spec.)
CIRCUIT DESCRIPTION
Fuel trim refers to the feedback compensation value compared against the basic injection time. Fuel trim
includes short±term fuel trim and long±term fuel trim.
Short±term fuel trim is the short±term fuel compensation used to maintain the air±fuel ratio at its ideal
theoretical value. The signal from the heated oxygen sensor indicates whether the air±fuel ratio is RICH or
LEAN compared to the ideal theoretical value, triggering a reduction in fuel volume if the air±fuel ratio is rich,
and an increase in fuel volume if it is lean.
Long±term fuel trim is overall fuel compensation carried out long±term to compensate for continual deviation
of the short±term fuel trim from the central value due to individual engine differences, wear over time and
changes in the usage environment.
If both the short±term fuel trim and long±term fuel trim are LEAN or RICH beyond a certain value, it is
detected as a malfunction and the MIL lights up.
DTC No.DTC Detecting ConditionTrouble Area
P0171
When air fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on RICH side
(2 trip detection logic)

Air intake (hose loose)

Fuel line pressure

Injector blockage

Heated oxygen sensors (bank 1, 2 sensor 1) malfunction

Mass air flow meter

Engine coolant temp. sensor

Gas leakage on exhaust system
P0172
When air fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on LEAN side
(2 trip detection logic)

Fuel line pressure

Injector leak, blockage

Heated oxygen sensors (bank 1, 2 sensor 1) malfunction

Mass air flow meter

Engine coolant temp. sensor

Gas leakage on exhaust system
HINT:

When DTC P0171 is recorded, the actual air±fuel ratio is on the LEAN side. When DTC P0172 is re-
corded, the actual air±fuel ratio is on the RICH side.

If the vehicle runs out of fuel, the air±fuel ratio is LEAN and DTC P0171 is recorded. The MIL then
comes on.

If the total of the short±term fuel trim value and long±term fuel trim value is within + 35 % (80°C (176°F)
or more), the system is functioning normally.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
DI4DR±01

DI±276
± DIAGNOSTICSENGINE (1MZ±FE)
511 Author: Date:
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
DTC P0305 Cylinder 5 Misfire Detected
DTC P0306 Cylinder 6 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.
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
P0300Misfiring of random cylinders is detected during any
particular 200 or 1,000 revolutions
Ignition system

Injector

Fuel line pressure
P0301
P0302
P0303For any particular 200 revolutions for engine, misfiring is de-
tected which can cause catalyst overheating
(This causes MIL to blink)

EGR

Compression pressure

Valve clearance not to specification

Valve timing

Mass air flow meterP0303
P0304
P0305
P0306For any particular 1,000 revolutions of engine, misfiring is de-
tected which causes a deterioration in emission
(2 trip detection logic)

Mass air flow meter

Engine coolant temp. sensor

Open or short in engine wire

Connector connection

ECM
DI07S±07

A00199
ECM
Mass Air Flow MeterVSV
for
EGR
EGR Valve
Position
Sensor
EGR Valve EGR Gas
Temp. Sensor
Crankshaft Position Sensor Engine Coolant
Temp. SensorIntake Air
Chamber Throttle ValveVacuum
Control
Valve
DI±292
± DIAGNOSTICSENGINE (1MZ±FE)
527 Author: Date:
DTC P0401 Exhaust Gas Recirculation Flow
Insufficient Detected (Ex CA Spec.)
CIRCUIT DESCRIPTION
The EGR system recirculates exhaust gas, which is controlled to the proper quantity to suit the driving condi-
tions, into the intake air mixture to slow down combustion, reduce the combustion temperature and reduce
NOx emissions.
The lift amount of EGR valve is controlled by the vacuum which is regulated by the Duty±VSV operated by
the ECM. The lift amount of EGR valve is detected by the EGR valve position sensor which is mounted on
the EGR valve and it provides feedback to the ECM to control the lift amount of EGR valve in response to
engine operating conditions.
Under the following conditions, EGR is cut to maintain driveability.

Before the engine is warmed up

During deceleration (throttle valve closed)

Light engine load (amount of intake air very small)

Engine speed over 4,000 rpm

Engine idling
DTC No.DTC Detecting ConditionTrouble Area
P0401
After engine is warmed up and run at 80 km/h (50 mph) for 3 to
5 min. EGR gas temperature sensor valve does not exceed
35°C (95°F) above ambient air temperature
(2 trip detection logic)

EGR valve (stuck closed)

Open or short in EGR gas temp. sensor circuit

EGR gas temp. sensor

Open in VSV circuit for EGR

VSV for EGR

Vacuum control valve

Vacuum hose disconnected or blocked

ECM
DI4DS±01

DI±294
± DIAGNOSTICSENGINE (1MZ±FE)
529 Author: Date:
(1) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(2) Start and warm up the engine with all accessories switched OFF.
(3) Run the vehicle at 70 ~ 90 km/h (43 ~ 56 mph) for 3 min. or more.
(4) Idle the engine for about 2 min.
(5) Do steps (3) and (4) again.
(6) Stop at safe place and turn the ignition switch OFF.
(7) Do step (2) to (5) again.
(8) Check the READINESS TESTS mode on the OBD II scan tool or TOYOTA hand±held tester.
If COMPL is displayed and the MIL does not light up, the system is normal.
If INCMPL is displayed and the MIL does not light up, run the vehicle steps (2) to (6) from some times and
check it.
HINT:
INCMPL is displayed when either condition (a) or (b) exists.
(a) The system check is incomplete.
(b) There is a malfunction in the system.
If there is a malfunction in the system, the MIL light up after step (7) above is done.
(2trip detection logic)
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
TOYOTA hand±held tester
1 Connect TOYOTA hand±held tester, and read value of EGR gas temperature.
PREPARATION:
(a) Connect the TOYOTA hand±held tester to the DLC3.
(b) Warm up the engine.
CHECK:
Read EGR gas temperature on TOYOTA hand±held tester during idling.
OK:
EGR gas temperature : 55C (415F) ~ 1505C (3025F) (Not immediately after driving)
HINT:
If there is an open circuit, TOYOTA hand±held tester indicates 3.15C (37.65F).
If there is an short circuit, TOYOTA hand±held tester indicates 159.35C (318.75F).
OK Go to step 4.
NG

FI6514
OX Signal Waveform (Oscilloscope)
1 V
0 V
200 m sec./Division
DI±306
± DIAGNOSTICSENGINE (1MZ±FE)
541 Author: Date:
(a) Connect the TOYOTA hand±held tester to the DLC3, or connect the probe of the oscilloscope between
terminals OXR1, OXL1, OXS and E1 of the ECM connector.
(b) Start engine and warm it up with all accessories switched OFF until water temp. is stable.
(c) Race the engine at 2,500 ~ 3,000 rpm for about 3 min.
(d) After confirming that the waveform of the heated oxygen sensor, bank 1, 2 sensor 1 (OXR1, OXL1),
oscillate around 0.5 V during feedback to the ECM, check the waveform of the heated oxygen sensor,
bank 1 sensor 2 (OXS).
HINT:
If there is a malfunction in the system, the waveform of the
heated oxygen sensor, bank 1 sensor 2 (OXS), is almost the
same as that of the heated oxygen sensor, bank 1, 2 sensor 1
(OXR1, OXL1), on the left.
There are some cases where, even though a malfunction
exists, the MIL may either light up or not light up.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held theater or OBD II scan tool. Because freeze frame re-
cords the engine conditions when the malfunction is detected, when troubleshooting it is useful for determin-
ing whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich,
etc. at the time of the malfunction.
1 Are there any other codes (besides DTC P0420) being output?
YES Go to relevant DTC chart.
NO
2 Check gas leakage on exhaust system.
NG Repair or replace.
OK

A00364
Vehicle Speed
60 ~ 120 km/h
(38 ~ 75 mph)
Idling
IG SW OFF
3 ~ 5 min.
Time
(1) (2)(3)(4)
± DIAGNOSTICSENGINE (1MZ±FE)
DI±341
576 Author: Date:
CONFIRMATION DRIVING PATTERN
(a) Connect the TOYOTA hand±held tester to the DLC3.
(b) Switch the TOYOTA hand±held tester from normal mode to check mode (See page DI±197).
(c) Start the engine and warm it up with all accessory switches OFF.
(d) Drive the vehicle at 60 ~ 120 km/h (38 ~ 75 mph) and engine speed at 1,600 ~ 3,200 rpm for 3 ~ 5 min.
HINT:
If a malfunction exists, the MIL will light up during step (4).
NOTICE:
If the conditions in this test are not strictly followed, detection of the malfunction will not be possible.
If you do not have a TOYOTA hand±held tester, turn the ignition switch OFF after performing steps
(3) and (4), then perform steps (3) and (4) again.
INSPECTION PROCEDURE
HINT:

If DTC P1130 is displayed, check Bank 1 Sensor 1 circuit.

If DTC P1150 is displayed, check Bank 2 Sensor 1 circuit.

Read frame freeze data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame
records the engine conditions when the malfunction is detected, when troubleshooting it is useful for
determining whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel
ratio lean or rich, etc. at the time of the malfunction.
1 Are there any other codes (besides DTC P1130, P1150) being output?
YES Go to relevant DTC chart.
NO

A07449
Fusible
Link
Block
FL
MAINStop Light Switch
B±G1B 1CSTOP
WG±WLight
Failure
Sensor 7
2
To Stop Light Instrument Panel J/B
Instrument Panel J/B
E7 15
G±W
1S 1R
1R1
2
F9
F4
BatteryECM
STP
E1 B±R
ALT
G±WA
C
J27Junction
Connector
J2845
2
G±W7 4
1
1
± DIAGNOSTICSENGINE (1MZ±FE)
DI±363
598 Author: Date:
DTC P1520 Stop Light Switch Signal Malfunction
(Only for A/T)
CIRCUIT DESCRIPTION
This signal is used to detect when the brakes have been applied. The STP signal voltage is the same as
the voltage supplied to the stop lights.
The STP signal is used mainly to control the fuel cut±off engine speed (The fuel cut±off engine speed is re-
duced slightly when the vehicle is braking.).
DTC No.DTC Detecting ConditionTrouble Area
P1520
Stop light switch does not turn off when repeating the driving at
30 km or more 10 times or more after depressing brake
(2 trip detection logic)
Short in stop light switch signal circuit

Stop light switch

ECM
WIRING DIAGRAM
DI088±06

A02037
ON
ON
Brake Pedal
DepressedBrake Pedal
Released
STP (+)
DI±364
± DIAGNOSTICSENGINE (1MZ±FE)
599 Author: Date:
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
1 Check operation of stop light.
CHECK:
Check if the stop lights go on and off normally when the brake pedal is operated and released.
NG Check and repair stop light circuit.
OK
2 Check STP signal.
When using TOYOTA hand±held tester:
PREPARATION:
(a) Connect the TOYOTA hand±held tester to the DLC3.
(b) Turn the ignition switch ON and push the TOYOTA hand±
held tester main switch ON.
CHECK:
Read the STP signal on the TOYOTA hand±held tester.
OK:
Brake pedal is depressed: STP ...... ON
Brake pedal is released: STP ...... OFF
When not using TOYOTA hand±held tester:
PREPARATION:
Turn the ignition switch ON.
CHECK:
Check voltage between terminal STP of the ECM connector
and body ground.
OK:
Brake pedalVoltage
Depressed7.5 ~ 14 V
ReleasedBelow 1.5 V
OK Check for intermittent problems
(See page DI±197).
NG