1996 TOYOTA LAND CRUISER engine coolant

−
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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−
DIAGNOSTICS ENGINE
DI−53
1996 LAND CRUISER (RM451U)
5 Check mass air flow meter and engine coolant temp. sensor
(See page SF−40 , SF−61 ).
NG Repair or replace.
OK
6 Check for spark and ignition (See page IG−1).
NG Repair or replace.
OK
Check and replace ECM (See page IN−28 ).
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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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DI−58
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
5 Check injector injection (See page SF−29).
NG Replace injector.
OK
6 Check EGR system (See page EC−11 ).
NG Repair EGR system.
OK
7 Check mass air flow meter and engine coolant temp. sensor (See page SF−40 ,
SF−61 ).
NG Repair or replace.
OK
Check engine mechanical systems compression pressure (See page EM−3), valve clearance
(See page EM−4) and valve timing (See page EM−13).
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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
(+)
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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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−
DIAGNOSTICS ENGINE
DI−93
1996 LAND CRUISER (RM451U)
DTC P0510 Closed Throttle Position Switch Malfunction
CIRCUIT DESCRIPTION
Refer to DTC P0120 (Throttle/Pedal Position Sensor/Switch ”A” Circuit \
Malfunction) on page DI−35.
DTC No.DTC Detecting ConditionTrouble Area
P0510
The closed throttle position switch does not turn ON or OFF
even once when the vehicle is driven
(2 trip detection logic)Open or short in closed throttle position switch circuit
 Closed throttle position switch
 ECM
HINT:
After confirming DTC P0510 use the TOYOTA hand−held tester to confirm the closed throttle position switch
signal from ”CURRENT DATA”.
Throttle ValveClosed Throttle Position Switch SignalMalfunction
Fully closedOFFOpen circuit
Fully openONShort circuit
WIRING DIAGRAM
Refer to DTC P0120 (Throttle/Pedal Position Sensor/Switch ”A” Circuit Malfunction) on page DI−35 for WIR-
ING DIAGRAM.
INSPECTION PROCEDURE
HINT:
If DTCs P0110 (Intake Air Temp. Circuit Malfunction), P0115 (Engine Coolant Temp. Circuit Malfunction),
P0120 (Throttle/Pedal Position Sensor/Switch ”A” Circuit Malfunction)\
are output simultaneously, E2 (Sen-
sor Ground) may be open.
TOYOTA hand −held tester
1 Connect the TOYOTA hand −held tester and read CTP switch signal.
PREPARATION:
(a) Remove the fuse cover on the instrument panel.
(b) Connect OBD II scan tool or TOYOTA hand−held tester to the DLC3.
(c) Turn ignition switch ON and OBD II scan tool or TOYOTA hand−held tester main switch ON.
CHECK:
Read CTP switch signal on TOYOTA hand −held tester.
RESULT:
Throttle ValveClosed Throttle Position Switch SignalMalfunction
Fully closedOFFOpen circuit: Go to step 2
Fully openONShort circuit: Go to step 4
DI5PP−02
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