1996 TOYOTA LAND CRUISER air condition

−
DIAGNOSTICS ENGINE
DI−49
1996 LAND CRUISER (RM451U)
DTC P0136 Heated Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page DI−40.
DTC No.DTC Detecting ConditionTrouble Area
P0136
Voltage output of the heated oxygen sensor (bank 1 sensor 2)
remains at 0.4 V or more or 0.5 V or less when the vehicle is
driven at 40 km/h (25 mph) or more after the engine is warmed
up. (2 trip detection logic).
Heated oxygen sensor (bank 1 sensor 2)
HINT:
Sensor 2 refers to the sensor farther away from the engine body.
WIRING DIAGRAM
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page DI−40 for WIRING
DIAGRAM.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0136) being output?
YES Go to relevant DTC chart.
NO
2 Check for open and short in harness and connector between ECM and heated\
oxygen sensor (bank 1 sensor 2) (See page IN−28 ).
NG Repair or replace harness or connector.
OK
DI5PD−02
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−
DIAGNOSTICS ENGINE
DI−51
1996 LAND CRUISER (RM451U)
DTC P0171 System too Lean (Fuel Trim)
DTC P0172 System too Rich (Fuel Trim)
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 a\
ir −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 devi-
ation of the short−term fuel trim form 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 de-
tected as a malfunction and the MIL lights up.
DTC No.DTC Detecting ConditionTrouble Area
P0171
When the air fuel ratio feedback is stable after engine warming
up, the fuel trim is considerably in error on the RICH side.
(2 trip detection logic)
 Air intake (hose loose)
 Fuel line pressure
 Injector blockage, leak
 Heated oxygen sensor (bank 1 sensor 1) malfunction
 Mass air flow meter
 Engine coolant temp. sensor
P0172
When the air fuel ratio feedback is stable after engine warming
up, the fuel trim is considerably in error on the LEAN side.
(2 trip detection logic)
Fuel line pressure
 Injector blockage, leak
 Heated oxygen sensor (bank 1 sensor 1) malfunction
 Mass air flow meter
 Engine coolant temp. sensor
HINT:
When the DTC P0171 is recorded, the actual air− fuel ratio is on the LEAN side. When DTC P0172 is
recorded, the actual air−fuel ratio is on the RICH side.
If the total of the short −term fuel trim value and long −term fuel trim value is within + 30 − − 35 %, the
system is functioning normally.
If the vehicle runs out of fuel, the air −fuel ratio is LEAN and DTC P0171 is recorded. The MIL then come
on.
INSPECTION PROCEDURE
1 Check air induction system (See page SF−1 ).
NG Repair or replace
OK
DI5PE−02
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DI−52
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
2 Check for heated oxygen sensor (bank 1 sensor 1) data.
PREPARATION:
(a) Remove the fuse cover on the instrument panel.
(b) Connect the OBD II scan tool or TOYOTA hand−held tester to the DLC3.
(c) Warm up engine to normal operating temperature.
CHECK:
Read the heated oxygen sensor (bank 1 sensor 1) output voltage and sho\
rt −term fuel trim.
RESULT:
PatternHeated o xygen sensor (bank 1 sensor 1) output voltageShort−term fuel trim
1Lean condition (Changes at 0.55 V or less)Changes at about +20 %
2Rich condition (Changes at 0.4 V or more)Changes at about −20 %
3Except 1 and 2
3 Check for heated oxygen sensor
(bank 1 sensor 1) (See page SF−64 ).
1, 2
3 Check fuel pressure (See page SF−6 ).
NG Check and repair fuel pump, pressure
regulator, fuel pipe line and filter
(See page SF−1 ).
OK
4 Check injector injection (See page SF−29).
NG Replace injector.
OK
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DI−54
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
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 senso\
r 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 deteriorat\
ed, 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 the any partic-
ular 200 or 1,000 revolutions Ignition system
 Injector
 Fuel line pressure
 EGR
 Compression pressure
 Valve clearance not to specification
 Valve timing
 Mass air flow meter
 Engine coolant temp. sensor
P0301
P0302
P0303
P0304
P0305
P0306For any particular 200 revolutions of the engine, misfiring is
detected which can cause catalyst overheating
(This causes MIL to blink)
For any particular 1,000 revolutions of the engine, misfiring is
detected which causes a deterioration in emission
(2 trip detection logic)
HINT:
When the 2 or more codes for a misfiring cylinder are recorded repeatedly bu\
t no random misfire code is
recorded, it indicates that the misfires were detected and recorded at d\
ifferent times.
DI5PF−02
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S06273
E1
1
G−
2
BR
L
L G1
NE2
NE2−
12
E6
3
2
Distributor
Crankshaft Position Sensor G2
ECM
NE
4
1 L
L
G W
R
E6
E6
E6
E6
E6 11
10 4
56
DI−62
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
DTC P0335 Crankshaft Position Sensor ”A” Circuit Malfunction
CIRCUIT DESCRIPTION
The crankshaft position sensor (NE signal) consists of a signal plate and pick up coil. The NE\
signal plate
has 24 teeth and is built into the distributor. When the camshaft rotates, the protrusion on the signal plate
and the air gap on the pick up coil change, causing fluctuations in the magnetic field and generating an elec-
tromotive force in the pick up coil. The NE signal sensor generates 24 signals fo\
r every engine revolution.
The ECM detects the standard crankshaft angle based on the G1, G2 signals, \
detects the actual crankshaft
angle and the engine speed by the NE signals, and detects misfire by NE2 sign\
als.
DTC No.DTC Detecting ConditionTrouble Area
P0335
No crankshaft position sensor signal (NE signal) to ECM dur-
ing cranking.
(2 trip detection logic) Open or short in crankshaft position sensor circuit for NE
signal.
 Crankshaft position sensor for NE signal
 Starter
 ECM
No crankshaft position sensor signal (NE signal) to ECM with
engine speed 550 rpm or more (2 trip detection logic)
WIRING DIAGRAM
DI5PH−02
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P24663
2(−)
3
4 1
(+)
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DIAGNOSTICS ENGINE
DI−65
1996 LAND CRUISER (RM451U)
DTC P0340 Camshaft Position Sensor Circuit
Malfunction
CIRCUIT DESCRIPTION
The camshaft position sensors (G1 and G2 signals) consist of a signal pla\
te and a pick up coil. The G1, G2,
signal plates each have one tooth on the outer circumference and are built int\
o the distributor. When the
camshaft rotates, the protrusion on the signal plate and the air gap on the pick \
up coil change, causing fluc-
tuations in the magnetic field and generating an electromotive force in the pick \
up coil. The ECM detects the
standard crankshaft angle based on the G1, G2 signals, detects the actual cranks\
haft angle and engine
speed by the NE signals, and detects misfire by NE2 signals.
DTC No.DTC Detecting ConditionTrouble Area
P0340No camshaft position sensor signal (G signal) to ECM with
engine speed 550 rpm or more. Open or short in camshaft position sensor circuit
 Camshaft position sensor
 ECM
WIRING DIAGRAM
Refer to DTC P0335 (Crankshaft Position Sensor ”A” Circuit Malfunction) o\
n page DI−62 for the WIRING
DIAGRAM.
INSPECTION PROCEDURE
1 Check resistance of camshaft position sensor.
PREPARATION:
Disconnect camshaft position sensor connector.
CHECK:
Measure resistance between terminals 2, 3 and 4 of distributor
connector.
OK:
Resistance
Cold185 − 275 Ω
Hot240 − 325 Ω
”Cold” is from − 10°C (14°F) to 50°C (122°F) of engine coolant
temperature and "Hot" is from 50°C (122°F) to 100°C (212°\
F).
Reference: INSPECTION USING OSCILLOSCOPE
Refer to page DI−62 for Reference INSPECTION USING OS-
CILLOSCOPE.
NG Replace distributor housing assembly.
OK
DI5PI−02
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A00167P22894
P24664
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DIAGNOSTICS ENGINE
DI−67
1996 LAND CRUISER (RM451U)
DTC P0385 Crankshaft Position Sensor ”B” Circuit
Malfunction
CIRCUIT DESCRIPTION
The crankshaft position sensor (NE2 signal) consists of a signal plate and a pick up coil. The NE2 signal plate
has 34 teeth and is mounted on the crankshaft. When the crankshaft rotates, the protrusion on the signal
plate and the air gap on the pick up coil change, causing fluctuations i\
n the magnetic field and generating
an electromotive force in the pick up coil. The NE2 signal sensor generate\
s 34 signals for every engine revo-
lution. The ECM detects the standard crankshaft angle based on G1, G2 signals d\
etects the actual crank-
shaft angle and the engine speed by NE signals, and detects misfire by NE2 si\
gnals.
DTC No.DTC Detecting ConditionTrouble Area
P0385
No crankshaft position sensor signal (NE 2 signal) to ECM
during cranking. (2 trip detection logic) Open or short in crankshaft position sensor for NE2 signals.
 Crankshaft position sensor for NE2 signal.
 ECM
No crankshaft position sensor signal (NE 2 signal) to ECM with
engine speed 550 rpm or more. (2trip detection logic)
WIRING DIAGRAM
Refer to DTC 0335 (Crankshaft Position Sensor ”A” Circuit Malfunction)\
on page DI−62 for WIRING DIA-
GRAM.
INSPECTION PROCEDURE
1 Check resistance of crankshaft position sensor for NE2 signal.
PREPARATION:
Disconnect crankshaft position sensor connector.
CHECK:
Measure resistance between terminals 1 and 2 of crankshaft
position sensor connector.
OK:
Resistance
Cold1630 − 2740 Ω
Hot2065 − 3225 Ω
”Cold” is from − 10°C (14°F) to 50°C (122°F) of engine coolant
temperature and "Hot" is from 50°C (122°F) to 100°C (212°F).
Reference: INSPECTION USING OSCILLOSCOPE
Refer to page DI−62 for Reference INSPECTION USING OS-
CILLOSCOPE.
NG Replace crankshaft position sensor.
OK
DI5PJ−02
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P22417
Exhaust
Gas
Intake Air
Chamber EGR
Valve
VSV
EGR
Vacuum
Modulator
ECM
Throttle
valve
P22426
BR
From Battery R/B No.2
R−Y
2
222
2
2
Y−R
EFI Main
Y−R
1
2
43
REA2
EZ1
EB12 7
VSV for EGR 21
YYL
−W
EZ14
EGR Gas T emp.
Sensor
21
G−Y
BR−BE7 E4
E4
E5 3
22
19
9
THG
E1
EGR
E2 5V
MRLY
ECM
R
EB
EFI
1
Relay
B+
E01
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DIAGNOSTICS ENGINE
DI−69
1996 LAND CRUISER (RM451U)
DTC P0401 Exhaust Gas Recirculation Flow Insufficient
Detected
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 combust\
ion temp. and reduce NOx
emissions. The amount of EGR is regulated by the EGR vacuum modulator ac\
cording to the engine load.
If even one of the following conditions is fulfilled, the VSV is
turned ON by a signal from the ECM.
This results in atmospheric air acting on the EGR valve, closing
the EGR valve and shutting off the exhaust gas (EGR cut− off).
Under the following conditions, EGR is cut to maintain driveabil-
ity.
Before the engine is warmed up.
During deceleration (throttle valve closed).
Light engine load (amount of intake air very small).
Engine racing.
DTC No.DTC Detecting ConditionTrouble Area
P0401
After the engine is warmed up and run at 80 km/h (50 mph)
for 3 to 5 minutes, the EGR gas temperature sensor value
does not exceed 38° C (100.4°F) above the ambient air tem-
perature. (2 trip detection logic) EGR valve stuck closed
 Short in VSV circuit for EGR
 Open in EGR gas temp. sensor circuit
 EGR hose disconnected
 ECM
WIRING DIAGRAM
DI5PK−02
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