1996 TOYOTA LAND CRUISER Position

−
DIAGNOSTICS ENGINE
DI−39
1996 LAND CRUISER (RM451U)
DTC P0121 Throttle/Pedal Position Sensor/Switch ”A”
Circuit Range/Performance Problem
CIRCUIT DESCRIPTION
Refer to DTC P0120 (Throttle/Pedal Position Sensor/Switch "A" Circuit Malfunction) on page DI−35.
DTC No.DTC Detection ConditionTrouble Area
P0121
After the vehicle speed has been exceeded 30 km/h (19 mph)
even once, the output value of the throttle position sensor is
out of the applicable range while the vehicle speed between 30
km/h (19 mph) and 0 km/h (0 mph).
Throttle position sensor
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0121) being output?
YES Go to relevant DTC chart.
NO
Replace throttle position sensor.
DI5P8−02
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P21242 FI7210A00027
Atmosphere
Flange
Platinum Electrode
Solid Electrolyte
(Zirconia Element)
Platinum Electrode
Heater
Coating (Ceramic)
Exhaust GasCover Ideal Air−
Fuel Mixture
Output Voltage
Richer − Air Fuel Ratio − Leaner
DI−40
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of th\
e exhaust gas, a three −way cata-
lytic converter is used, but for the most efficient use of the three −way catalytic converter, the air−fuel ratio
must be precisely controlled so that it is always close to the stoichiom\
etric air −fuel ratio.
The oxygen sensor has the characteristic where by its output voltage change\
s suddenly in the vicinity of the
stoichiometric air −fuel ratio. This characteristic is used to detect the oxygen concentrati\
on in the exhaust
gas and provide feedback to the computer for control of the air −fuel ratio.
When the air −fuel ratio becomes LEAN, the oxygen concentration in the exhaust increas\
es and the oxygen
sensor informs the ECM of the LEAN condition (small electromotive force: 0 V)\
.
When the air −fuel ratio is RICHER than the stoichiometric air −fuel ratio the oxygen concentration in the ex-
haust gas in reduced and the oxygen sensor informs the ECM of the RICH condit\
ion (large electromotive
force: 1 V). The ECM judges by the electromotive force from the oxygen \
sensor whether the air −fuel ratio
is RICH or LEAN and controls the injection time accordingly. However, if malfunction of the oxygen sensor
causes output of abnormal electromotive force, the ECM is unable to perform acc\
urate air −fuel ratio control.
The heated oxygen sensors include a heater which heats the zirconia element\
. The heater is controlled by
the ECM. When the intake air volume is low (the temp. of the exhaust gas i\
s low) current flows to the heater
to heat the sensor for accurate oxygen concentration detection.
DTC No.DTC Detecting ConditionTrouble Area
P0125
After the engine is warmed up, heated oxygen sensor (bank 1
sensor 2) output does not indicate RICH even once when
conditions (a), (b) and (c) continue for at least 1.5 min.
(a) Engine speed: 1,500 rpm or more
(b) Vehicle speed: 40 − 100 km/h (25 − 62 mph)
(c) Closed throttle position switch: OFF
 Open or short in heated oxygen sensor (bank 1 sensor 1)
circuit
 Heated oxygen sensor (bank1 sensor 1)
DI5P9−02
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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
1
23
4
(−) (+)
P23505
G, NE signal waveforms
20 m sec/Division (Idling) 5V/DIV
G1
G2
NE
NE2
−
DIAGNOSTICS ENGINE
DI−63
1996 LAND CRUISER (RM451U)
INSPECTION PROCEDURE
1 Check resistance of crankshaft position sensor for NE signal.
PREPARATION:
Remove the distributor cap and disconnect distributor connec-
tor.
CHECK:
Measure resistance between terminals 1 and 4 of distributor
connector.
OK:
Resistance
Cold185 − 275 Ω
Hot240 − 325 Ω
”Cold” is from − 10°C (14F° ) to 50°C (122°F) of engine coolant
temperature sensor and ”Hot” is from 50 °C (122° F) to 100° C
(212 °F).
Reference: INSPECTION USING OSCILLOSCOPE
During cranking or idling, check between terminals G1, G2, NE,
NE2 and G− of ECM.
HINT:
The correct waveforms are as shown.
NG Replace distributor housing assembly.
OK
2 Check for open and short in harness and connector between ECM and crank-\
shaft position sensor for NE signal (See page IN−28).
NG Repair or replace harness or connector.
OK
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P24663
2(−)
3
4 1
(+)
−
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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DI−66
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
2 Check for open and short in harness and connector between ECM and camshaft
position sensor (See page IN−28).
NG Repair or replace harness or connector.
OK
3 Check air gap (See page IG−1 ).
NG Replace distributor housing assembly.
OK
Check and replace ECM (See page IN−28 ).
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A00167P22894
P24664
−
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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