1998 TOYOTA LAND CRUISER fuel pressure

+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Case 1
Case 2
Case 3
Case 4
Output voltage of heated oxygen
sensor (sensor 1: front sensor)
Injection volume
Output voltage
Output voltage of heated oxygen
sensor (sensor 2: rear sensor)Mainly suspect
trouble area
OK
+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
Sensor 1: front sensor
(sensor 1, heater, sensor 1
circuit)
+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
+25 %
-12.5 %
Injection volume
Output voltage
NG
+25 %
-12.5 %
Injection volume
Output voltage
NG
+25 %
-12.5 %
Injection volume
Output voltage
NG
+25 %
-12.5 %
Injection volume
Output voltage
NGExtremely rich or lean of the
actual air-fuel ratio
(Injector, fuel pressure, gas
leakage in exhaust system,
etc.) OK
OK
OK
Almost no reaction
'
Sensor 2: rear sensor
(sensor 2, heater, sensor 2
circuit)
Almost no reactionAlmost no reaction
Almost no reaction
DI-142
- DIAGNOSTICSENGINE
335 Author
: Date
:
2004 LAND CRUISER (RM1071U)
INSPECTION PROCEDURE
HINT:
Hand-held tester only:
The narrowing down the trouble area is possible by performing ACTIVE TEST of the following ºA/F CON-
TROLº (Heated oxygen sensor or another can be distinguished).
(a) Perform ACTIVE TEST by hand-held tester (A/F CONTROL).
HINT:
ºA/F CONTROLº is the ACTIVE TEST which changes the injection volume to -12.5 % or +25 %.
(1) Connect the hand-held tester to the DLC3 on the vehicle.
(2) Turn the ignition switch ON.
(3) Warm up the engine with the engine speed at 2,500 rpm for approximately 90 seconds.
(4) Select the item ºDIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROLº.
(5) Perform ºA/F CONTROLº with the engine in an idle condition (press the right or left button).
RESULT:
Heated oxygen sensor reacts in accordance with increase and decrease of injection volume
+25 % " rich output: More than 0.5 V
-12.5 % " lean output: Less than 0.4 V
NOTICE:
However, there is a few seconds delay in the sensor 1 (front sensor) output. And there is about 20
seconds delay in the sensor 2 (rear sensor).

- DIAGNOSTICSENGINE
DI-147
340 Author
: Date
:
2004 LAND CRUISER (RM1071U)
DTC P0171 System too Lean (Bank 1)
DTC P0172 System too Rich (Bank 1)
DTC P0174 System too Lean (Bank 2)
DTC P0175 System too Rich (Bank 2)
CIRCUIT DESCRIPTION
The fuel trim is related to the feedback compensation value, not to the basic injection time. The fuel trim in-
cludes the short-term fuel trim and the long-term fuel trim.
The short-term fuel trim is the short-term fuel compensation used to maintain the air-fuel ratio at stoichio-
metric air-fuel ratio. The signal from the heated oxygen sensor indicates whether the air-fuel ratio is RICH
or LEAN compared to the stoichiometric air-fuel ratio. This variance triggers a reduction in the fuel volume
if the air-fuel ratio is RICH, and an increase in the fuel volume if it is LEAN.
The long-term fuel trim is the overall fuel compensation carried out in long-term to compensate for a continu-
al deviation of the short-term fuel trim from the central value, due to individual engine differences, wear over-
time and changes in the operating environment.
If both the short-term fuel trim and the long-term fuel trim are LEAN or RICH beyond a certain value, it is
detected as a malfunction and the MIL is illuminated and a DTC is set.
DTC No.DTC Detecting ConditionTrouble Area
P0171
P0174When air-fuel ratio feedback is stable after warming up engine,
fuel trim is considerably in error on LEAN side
(2 trip detection logic)
Air induction system
Injector blockage
Mass air flow meter
Engine coolant temperature sensor
Fuel pressure
Gas leakage in exhaust system
Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit
Heated oxygen sensor (bank 1, 2 sensor 1)
Heated oxygen sensor heater (bank 1, 2 sensor 1)
EFI or ECD relay
PCV piping
ECM
P0172
P0175When air-fuel ratio feedback is stable after warming up engine,
fuel trim is considerably in error on RICH side
(2 trip detection logic)
Injector leak, blockage
Mass air flow meter
Engine coolant temperature sensor
Ignition system
Fuel pressure
Gas leakage in exhaust system
Open or short in heated oxygen sensor (bank 1, 2 sensor 1)
circuit
Heated oxygen sensor (bank 1, 2 sensor 1)
ECM
DIC2A-01

+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Case 1
Case 2
Case 3
Case 4
Output voltage of heated oxygen
sensor (sensor 1: front sensor)
Injection volume
Output voltage
Output voltage of heated oxygen
sensor (sensor 2: rear sensor)Mainly suspect
trouble area
OK
+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
Sensor 1: front sensor
(sensor 1, heater, sensor 1
circuit)
+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
+25 %
-12.5 %
Injection volume
Output voltage
NG
+25 %
-12.5 %
Injection volume
Output voltage
NG
+25 %
-12.5 %
Injection volume
Output voltage
NG
+25 %
-12.5 %
Injection volume
Output voltage
NGExtremely rich or lean of the
actual air-fuel ratio
(Injector, fuel pressure, gas
leakage in exhaust system,
etc.) OK
OK
OK
Almost no reaction
'
Sensor 2: rear sensor
(sensor 2, heater, sensor 2
circuit)
Almost no reactionAlmost no reaction
Almost no reaction
DI-150
- DIAGNOSTICSENGINE
343 Author
: Date
:
2004 LAND CRUISER (RM1071U)
INSPECTION PROCEDURE
HINT:
Hand-held tester only:
The narrowing down the trouble area is possible by performing ACTIVE TEST of the following ºA/F CON-
TROLº (Heated oxygen sensor or another can be distinguished).
(a) Perform ACTIVE TEST by hand-held tester (A/F CONTROL).
HINT:
ºA/F CONTROLº is the ACTIVE TEST which changes the injection volume to -12.5 % or +25 %.
(1) Connect the hand-held tester to the DLC3 on the vehicle.
(2) Turn the ignition switch ON.
(3) Warm up the engine with the engine speed at 2,500 rpm for approximately 90 seconds.
(4) Select the item ºDIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROLº.
(5) Perform ºA/F CONTROLº with the engine in an idle condition (press the right or left button).
RESULT:
Heated oxygen sensor reacts in accordance with increase and decrease of injection volume
+25 % " rich output: More than 0.5 V
-12.5 % " lean output: Less than 0.4 V
NOTICE:
However, there is a few seconds delay in the sensor 1 (front sensor) output. And there is about 20
seconds delay in the sensor 2 (rear sensor).

DI-154
- DIAGNOSTICSENGINE
347 Author
: Date
:
2004 LAND CRUISER (RM1071U)
7 Check fuel pressure (See page SF-7).
CHECK:
Check the fuel pressure (high or low pressure).
NG Check and replace fuel pump, pressure regula-
tor, fuel pipe line and filter (See page SF-1).
OK
8 Check exhaust system for gas leakage.
NG Repair or replace exhaust gas leakage point.
OK

A20646
20V
/Division Injector Signal Waveform
20V
/Division
GND
100 msec./Division (Idling)(Magnification)
GND
1 msec./Division (Idling)
Injection duration
DI-168
- DIAGNOSTICSENGINE
361 Author
: Date
:
2004 LAND CRUISER (RM1071U)DTC No.
DTC Detecting ConditionTrouble Area
P0300Misfiring of random cylinders is detected

Open or short in engine wire

Connector connection

Vacuum hose connection
P0301
P0302
P0303
P0304
P0305
P0306
P0307
P0308
Misfiring of each cylinder is detected

Vacuum hose connection

Ignition system

Injector

Fuel pressure

Mass air flow meter

Engine coolant temperature sensor

Compression pressure

Valve clearance

Valve timing

PCV piping

ECM
HINT:
When several codes for a misfiring cylinder are recorded repeatedly but no random misfire code is recorded,
it indicates that the misfires have been detected and recorded at different times.
Reference: Inspection using the oscilloscope.
With the engine idling, check the waveform between terminals #1 to #8 and E01 of the ECM connectors.
HINT:
The correct waveform is as shown.

- DIAGNOSTICSENGINE
DI-183
376 Author
: Date
:
2004 LAND CRUISER (RM1071U)
15 Check valve timing (Check for looseness or a jumped tooth of timing belt)
(See page EM-22).
NG Adjust valve timing (Repair or replace timing
belt).
OK
16 Check fuel pressure (See page SF-7).
NG Check and repair fuel pump, pressure regulator,
fuel pipe line and filter (See page SF-1).
OK

+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Case 1
Case 2
Case 3
Case 4
Output voltage of heated oxygen
sensor (sensor 1: front sensor)
Injection volume
Output voltage
Output voltage of heated oxygen
sensor (sensor 2: rear sensor)Mainly suspect
trouble area
OK
+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
Sensor 1: front sensor
(sensor 1, heater, sensor 1
circuit)
+25 %
-12.5 %
More than 0.5 V
Less than 0.4 V
Injection volume
Output voltage
+25 %
-12.5 %
Injection volume
Output voltage
NG
+25 %
-12.5 %
Injection volume
Output voltage
NG
+25 %
-12.5 %
Injection volume
Output voltage
NG
+25 %
-12.5 %
Injection volume
Output voltage
NGExtremely rich or lean of the
actual air-fuel ratio
(Injector, fuel pressure, gas
leakage in exhaust system,
etc.) OK
OK
OK
Almost no reaction
'
Sensor 2: rear sensor
(sensor 2, heater, sensor 2
circuit)
Almost no reactionAlmost no reaction
Almost no reaction
- DIAGNOSTICSENGINE
DI-221
414 Author
: Date
:
NOTICE:
However, there is a few second delay in the sensor 1 (front sensor) output. And there is about 20 se-
conds delay in the sensor 2 (rear sensor).
The following A/F CONTROL procedure enables the technician to check and graph the voltage output of
the heated oxygen sensors (sensor 1 and 2).
For displaying the graph indication, enter ºACTIVE TEST / A/F CONTROL / USER DATAº then select ºO2S
B1S1 and O2S B1S2º by pressing ºYESº button and push ºENTERº button before pressing ºF4º button.
NOTICE:
If the vehicle is short of fuel, the air-fuel ratio becomes LEAN and DTCs P0133 and/or P0153 will be
recorded, and the MIL then comes on.

If different DTCs related to different systems while terminal E2 as ground terminal are output simulta-
neously, terminal E2 may be open.

Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records
the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determin-
ing whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio
was lean or rich, etc. at the time of the malfunction.

A high heated oxygen sensor (sensor 1) voltage (0.5 V or more) could be caused by a rich air fuel mix-
ture. Check for conditions that would cause the engine to run rich.

A low heated oxygen sensor (sensor 1) voltage (0.4 V or less) could be caused by a lean air fuel mix-
ture. Check for conditions that would cause the engine to run lean.

A19378A20057
ECM
EVAP VSV
Charcoal Canister
Fuel Tank Fig. 1
(2)
(3) (4) (6)
(8)
(9) (1)
(5)
(7)Vapor Pressure
Sensor
CCVPressure
Switching
Valve
DI-222
- DIAGNOSTICSENGINE
415 Author
: Date
:
DTC P0441 Evaporative Emission Control System Incor-
rect Purge Flow
DTC P0446 Evaporative Emission Control System Vent
Control Circuit
DTC P2418 Evaporative Emission System Valve Control
Circuit/Open
CIRCUIT DESCRIPTION
The vapor pressure sensor, canister closed valve (CCV), and pressure switching valve are used to detect
abnormalities in the evaporative emission control system.
The ECM decides whether there is an abnormality in the evaporative emission control system based on the
vapor pressure sensor signal.
DTCs P0441, P0446 and P2418 are recorded by the ECM when evaporative emissions leak from the compo-
nents within the dotted line in Fig. 1 below, or when there is a malfunction in either the EVAP VSV, the pres-
sure switching valve, or in the vapor pressure sensor itself.
DIC2H-01