1996 TOYOTA LAND CRUISER Engine control

DI−46
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
DTC P0133 Heated Oxygen Sensor Circuit Slow Response (Bank 1 Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page DI−40.
DTC No.DTC Detecting ConditionTrouble Area
P0133
Response time for the heated oxygen sensor’s voltage output
to change from rich to lean, or from lean to rich, is 1 sec. or
more during idling after the engine is warmed up
(2 trip detection logic)
Heated oxygen sensor (bank 1 sensor 1)
HINT:
Sensor 1 refers to the sensor closer to the engine body.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0133) being output?
YES Go to relevant DTC chart.
NO
Replace heated oxygen sensor
(bank 1 sensor 1).
DI5PB−02
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BE6653
P24460A00950
ON
HT1HT2
(−) (+)
−
DIAGNOSTICS ENGINE
DI−47
1996 LAND CRUISER (RM451U)
DTC P0135 Heated Oxygen Sensor Heater Circuit
Malfunction (Bank 1 Sensor 1)
DTC P0141 Heated Oxygen Sensor Heater 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
P0135
P0141
When the heater operates, heater current exceeds 2 A
(2 trip detection logic)Open or short in heater circuit of heated oxygen sensor
 Heated oxygen sensor heater
 ECM
Heater current of 0.25 A or less when the heater operates
(2 trip detection logic)
HINT:
Sensor 1 refers to the sensor closer to the engine body.
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 Check voltage between terminals HT1, HT2 of ECM connector and body ground.
PREPARATION:
(a) Remove instrument panel speaker No.1 panel (See page SF−65 ).
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminals HT1, HT2 of ECM connec-
tor and body ground.
HINT:
Connect terminal HT1 to bank 1 sensor 1.
Connect terminal HT2 to bank 1 sensor 2.
OK:
Voltage: 9 − 14 V
OK Check and replace ECM (See page IN−28 ).
NG
DI5PC−02
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−
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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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
−
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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P22487
No.1 Vehicle
Speed SensorCombination
Meter ECM
4−pulse
4−pulse
P22473
Combination Meter
3
C13 L−WL
−W8
E7 SPD ECM
5V
E1
From Cruise Control ECU
−
DIAGNOSTICS ENGINE
DI−87
1996 LAND CRUISER (RM451U)
DTC P0500 Vehicle Speed Sensor Malfunction
CIRCUIT DESCRIPTION
The vehicle speed sensor outputs a 4 − pulse signal for every revolution of the rotor shaft, which is rotated
by the transmission output shaft via the driven gear. After this signal is converted into a more precise rectan-
gular wavefrom by the waveform shaping circuit inside the combination meter, it is then transmitted to the
ECM. The ECM determines the vehicle speed based on the frequency of thes\
e pulse signals.
DTC No.DTC Detecting ConditionTrouble Area
P0500
No vehicle speed sensor signal to ECM under conditions (a)
and (b):
(2 trip detection logic)
(a) Park/neutral position switch is OFF.
(b) Vehicle is being driven. Open or short in No.1 vehicle speed sensor circuit
 No.1 vehicle speed sensor
 Combination meter
 ECM
WIRING DIAGRAM
DI5PN−02
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Version 1.11 - 03/16/2010

A00176
ONSPD
(+)
(−)
BE6653
P24668
AT7809
9 − 14 V
0
Turn the wheel
DI−88
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
INSPECTION PROCEDURE
1 Check operation of speedometer.
CHECK:
Drive the vehicle and check if the operation of the speedmeter in the co\
mbination meter is normal.
HINT:
The vehicle speed sensor is operating normally if the speedometer displa\
y is normal.
NG Check speedometer circuit (See page BE−2 ).
OK
2 Check voltage between terminal SPD of ECM connector and body ground.
PREPARATION:
(a) Remove instrument panel speaker No.1 panel (See page SF−65 ).
(b) Disconnect cruise control ECU connector.
(c) Shift the shift lever to neutral.
(d) Jack up a rear wheels on one side.
(e) Turn ignition switch ON.
CHECK:
Measure voltage between terminal SPD of ECM connector and
body ground when the wheel is turned slowly.
OK:
Voltage is generated intermittently.
NG Check and repair harness and connector between combination meter and ECM.
OK
Check and replace ECM (See page IN−28 ).
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P22234
From
Air
CleanerSignals ECM IAC ValveValve ShaftRotor
To Cylinders
Throttle Valve
Intake Air
Chamber
Coils
Valve
−
DIAGNOSTICS ENGINE
DI−89
1996 LAND CRUISER (RM451U)
DTC P0505 Idle Control System Malfunction
CIRCUIT DESCRIPTION
The step motor type IAC valve is located in front of the intake
air chamber. Intake air bypassing the throttle valve is directed
to the IAC valve through a passage. A step motor is built into
the IAC valve. It consists of four coils, a magnetic rotor, valve
shaft and valve. When current flows to the coils due to signals
from the ECM, the rotor turns and moves the valve shaft forward
or backward, changing the clearance between the valve and
the valve seat. In this way the intake air volume bypassing the
throttle valve is regulated, controlling the engine speed. There
are 125 possible positions to which the valve can be opened.
DTC No.DTC Detecting ConditionTrouble Area
P0505Idle speed continues to vary greatly from the target speed
(2 trip detection logic)
 IAC valve is stuck or closed
 Open or short in IAC valve circuit
 Open or short in A /C signal circuit
 Air intake (hose loose)
DI5PO−02
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P22475
BatteryFusible
Link
FL AM2
F7W−R
EA2
W−R
B−R B−R
EA2
B−R
B−W B−W
W−B
Distributor
Ignition
Coil 4
12
EA2
IH1
W−B
8 1
2
Noise
Filter 45
B 3
Igniter Tr2
2
1
IH2 IH2
B−G
B−G
B−Y B−YE4
E4 IGT
IGF Tr15V
ECM
1 3 11
6
IG Switch
1
EC
17 23
14 13
−
DIAGNOSTICS ENGINE
DI−97
1996 LAND CRUISER (RM451U)
DTC P1300 Igniter Circuit Malfunction
CIRCUIT DESCRIPTION
The ECM determines the ignition timing, turns on Tr1 at a predetermined angle ( °CA) before the desired
ignition timing and outputs and ignition signal (IGT) ”1” to the\
igniter.
Since the width of the IGT signal is constant, the dwell angle control circuit in \
the igniter determines the time
the control circuit starts primary current flow to the ignition coil based \
on the engine rpm and ignition timing
one revolution ago, that is, the time the Tr2 turns on.
When it reaches the ignition timing, the ECM turns Tr1 off and outputs the IGT signal ”O”.
This turns Tr2 off, interrupting the primary current flow and generating a high voltage i\
n the secondary coil
which causes the spark plug to spark. Also, by the counter electromotive forc\
e generated when the primary
current is interrupted, the igniter sends an ignition confirmation signal (IGF)\
to the ECM. The ECM stops fuel
injection as a fail safe function when the IGF signal is not input to the ECM.
DTC No.DTC Detecting ConditionTrouble Area
P1300No IGF signal to ECM for 6 consecutive IGT signals during
engine running Open or short in IGF or IGT circuit from igniter to ECM
 Igniter
 ECM
WIRING DIAGRAM
DI5PQ−02
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