1996 TOYOTA LAND CRUISER Idle control

−
DIAGNOSTICS ENGINE
DI−15
1996 LAND CRUISER (RM451U)
DTC No.
(See Page)
Detection ItemTrouble Area*MILMemory
P0420
( DI−84 )Catalyst System Efficiency
Below Threshold Three− way catalytic convertor
 Open or short in heated oxygen sensor circuit
 Heated oxygen sensor

P0500
( DI−87 )Vehicle Speed Sensor
Malfunction
Combination meter
 Open or short in speed sensor circuit
 ECM
 Vehicle speed sensor

P0505
( DI−89 )Idle Control System
Malfunction
IAC valve is stuck or closed
 Open or short in IAC valve circuit
 Open or short A/C signal circuit
 Air intake (hose loose)

P0510
( DI−93 )Closed Throttle Position
Switch MalfunctionOpen in closed throttle position switch circuit
 Closed throttle position switch
 ECM

P1300
( DI−97 )Igniter Circuit Malfunction
Open or short in IGF or IGT circuit from igniter to ECM
 Igniter
 ECM

P1335
( DI−102 )Crankshaft Position Sensor
Circuit Malfunction
(during engine running)
Open or short in crankshaft position sensor circuit for NE sig-
nal
 Crankshaft position sensor for NE signal
 Starter
 ECM
−
P1500
( DI−103 )Stater signal circuit MalfunctionOpen or short in starter signal circuit
 ECM−
P1600
( DI−105 )ECM BATT MalfunctionOpen in back up power source circuit
 ECM
P1605
( DI−107 )Knock Control CPU MalfunctionECM
P1780
( DI−108 )Park/Neutral Position Switch
MalfunctionShort in park/neutral position switch circuit
 Park/neutral position switch
 ECM

*: −  MIL does not light up,   MIL lights up
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DI5OY−03
−
DIAGNOSTICS ENGINE
DI−19
1996 LAND CRUISER (RM451U)
PROBLEM SYMPTOMS TABLE
When the malfunction code is not confirmed in the DTC check and the problem \
still can not be confirmed
in the basic inspection, then proceed to this step and perform troubleshooting according to the numbered
order given in the table below.
SymptomSuspect AreaSee page
Engine does not crank (Does not start)1. Starting systemST−16
No initial combustion (Does not start)1. ECM power source circuit
2. Fuel pump control circuitDI−11 0
DI−11 5
No complete combustion (Does not start)1. Fuel pump control circuitDI−11 5
Engine cranks normally (Difficult to start)
1. Starter signal circuit
2. Fuel pump control circuit
3. CompressionDI−103
DI−11 5 EM−3
Cold engine (Difficult to start)1. Starter signal circuit
2. Fuel pump control circuitDI−103DI−11 5
Hot engine (Difficult to start)
1. Starter signal circuit
2. Fuel pressure control circuit
3. Fuel pump control circuitDI−103
DI−125DI−11 5
High engine idle speed (Poor idling)1. A/C signal circuit
2. ECM power source circuitAC−5
DI−11 0
Low engine idle speed (Poor idling)1. A/C signal circuit
2. Fuel pump control circuitAC−5
DI−11 5
Rough idling (Poor idling)1. Compression
2. Fuel pump control circuitEM−3
DI−11 5
Hunting (Poor idling)1. ECM power source circuit
2. Fuel pump control circuitDI−11 0
DI−11 5
Hesitation/Poor acceleration (Poor driveability)1. Fuel pump control circuit
2. A/T faultyDI−11 5
DI−147
Surging (Poor driveability)1. Fuel pump control circuitDI−11 5
Soon after starting (Engine stall)1. Fuel pump control circuitDI−11 5
During A/C operation (Engine stall)1. A/C signal circuit
2. Engine control module (ECM)AC−5
IN−18
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FI6571
Throttle Position
SensorVCCVTA
IDLE2 ECM
5V
B+
−
DIAGNOSTICS ENGINE
DI−35
1996 LAND CRUISER (RM451U)
DTC P0120 Throttle/Pedal Position Sensor/Switch ”A”
Circuit Malfunction
CIRCUIT DESCRIPTION
The throttle position sensor is mounted in the throttle body and
detects the throttle valve opening angle.
When the throttle valve is fully closed, the IDL contacts in the
throttle position sensor are on, so the voltage at the terminal IDL
of the ECM becomes 0 V. At this time, a voltage of approximate-
ly 0.3 − 0.8 V is applied to terminal VTA of the ECM. When the
throttle valve is opened, the IDL contacts go off and thus the
power source voltage of approximately 12 V in the ECM is ap-
plied to the terminal IDL of the ECM. The voltage applied to the
terminal VTA of the ECM increases in proportion to the opening
angle of the throttle valve and becomes approximately 3.2 − 4.9
V when the throttle valve is fully opened. The ECM judges the
vehicle driving conditions from these signals input from termi-
nals VTA and IDL, and uses them as one of the conditions for
deciding the air− fuel ratio correction, power increase correction
and fuel −cut control etc.
DTC No.DTC Detecting ConditionTrouble Area
P0120
Condition (a) or (b) continues
(a) VTA < 0.1 V, and closed throttle position switch is OFF
(b) VTA > 4.9 VOpen or short in throttle position sensor circuit
 Throttle position sensor
 ECM
HINT:
If there is open circuit in IDL line, DTC P0120 does not indicate.
After confirming DTC P0120 use the OBD II scan tool or TOYOTA hand−held tester to confirm the
throttle valve opening percentage and closed throttle position switch condition\
.
Throttle valve opening position
expressed as percentage
Trouble Area
Throttle valve fully closedThrottle valve fully open
0 %0 %VCC line open
VTA line open or short
Approx. 99 %Approx. 100 %E2 line open
DI5P7−02
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FI7130
Vehicle Speed50 − 65 km/h
(31 − 40 mph)
Idling
IG SW OFF 1 − 3 min.1 min. Time
(1)(2)(3) (4)
(5)
−
DIAGNOSTICS ENGINE
DI−43
1996 LAND CRUISER (RM451U)
DTC P0130 Heated Oxygen Sensor Circuit Malfunction
(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
P0130
Voltage output of heated oxygen sensor (bank 1 sensor 1)
remains at 0.4 V or more, or 0.55 V or less, during idling after
the engine is warmed up (2 trip detection logic)Heated oxygen sensor (bank 1 sensor 1)
 Fuel trim malfunction
HINT:
Sensor 1 refers to the sensor closer to the engine body.
The heated oxygen sensor’s output voltage and the shortterm fuel trim value can be read using t\
he OBD
II scan tool or TOYOTA handheld tester.
WIRING DIAGRAM
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page DI−35 for WIRING
DIAGRAM.
CONFIRMATION DRIVING PATTERN
(1) Connect the TOYOTA hand−held tester to the DLC3.
(2) Switch the TOYOTA hand−held tester from normal mode to check mode (See page DI−3).
(3) Start the engine and warm it up withe all accessory switches OFF.
(4) Drive the vehicle at 50 − 65 km/h (31 − 40 mph) for 1 − 3 min. to warm up the heated oxygen sensor.
(5) Let the engine idle for 1 min.
HINT:
If a malfunction exists, the MIL will light up during step (5).
NOTICE:
If the conditions in this test are not strictly followed, detection of the\
malfunction will not be possible.
If you do not have a TOYOTA hand −held tester, turn the ignition switch OFF after performing steps
(3) to (5), then perform steps (3) to (5) again.
DI5PA−02
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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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P22478
Battery
FL AM1
Fusible Link
1F6
B−L
2
2 2
2
3
4
AM1
R/B No.2
Junction
Connector (J4)
Y Y
IG Switch
4 2
1 B−W
B−YFuse Block
GAUGE
Y
B
B 6IH14
B−W Park/Neutral
Position Switch
3
2 G−R G−W
O
O
IH2
To A/T Indicator Light
(Combination Meter)
Starter
1
S1 E7
E7
E7
17
16
22 NSW
E1B+
E1 E1
L
2 ECM
W
EA26
B
B
B−R
65 3
2IH1
21
B−W
IH2
DI−108
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
DTC P1780 Park/Neutral Position Switch Malfunction
CIRCUIT DESCRIPTION
The park/neutral position switch goes on when the shift lever is in the N o\
r P shift position. When it goes on
terminal NSW of the ECM is grounded to body ground via the starter relay, thus the terminal NSW voltage
becomes 0 V. When the shift lever is in the D, 2, L or R position, the park/neutral\
position switch goes off,
so the voltage of ECM, terminal NSW becomes battery voltage, the voltage of the ECM internal power
source. If the shift lever is moved from the N position to the D position, this signal is used for air\
−fuel ratio
correction and for idle speed control (estimated control), etc.
DTC No.DTC Detecting ConditionTrouble Area
P1780
2 or more switches are ON simultaneously for ”N”, ”2” and ”\
L”
position (2 trip detection logic)
 Short in park/neutral position switch circuit
 Park/neutral position switch
 ECMWhen driving under conditions (a) and (b) for 30 sec. or more
the park/neutral position switch is ON (N position):
(2 trip detection logic)
(a) Vehicle speed: 70 km/h (44 mph) or more
(b) Engine speed: 1,500 − 2,500 rpm
HINT:
After confirming DTC P1780 use the T OYOTA hand−held tester to confirm the PNP switch signal from ”CUR-
RENT DATA”.
WIRING DIAGRAM
DI5PV−02
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Q07310Control Shaft Lever(b)
(c)
Q07311
Neutral Basic Line
Bolt
Groove
−
DIAGNOSTICS AUTOMATIC TRANSMISSION
DI−139
1996 LAND CRUISER (RM451U)
(3) Return the control shaft lever 2 notches to N posi-
tion.
(4) Set the shift lever to N position.
(5) While holding the shift lever lightly toward the R
position side, adjust the control rod nut.
(6) Tighten the control rod nut.
Torque: 13 N·m (130 kgf·cm, 9 ft·lbf)
(7) Start the engine and make sure that the vehicle moves forward when shifting the lever from the N to
D position and reverses when shifting it to the R
position.
(g) Inspec and adjust park/neutral positoin switch. Check that the engine can be started with the shift lever
only in the N or P position, but not in other positions.
If not as stated above, carry out the following adjustment proce-
dure.
(1) Loosen the park/neutral position switch bolt and set
the shift lever to the N position.
(2) Align the groove and neutral basic line.
(3) Hold in position and tighten the bolt.
Torque: 13 N·m (130 kgf·cm, 9 ft·lbf) For continuity inspect of the park/neutral position
switch, see page DI−169 .
(h) Check the idle speed. Idle speed:
650 ± 50 rpm (In N position and air conditioner OFF)
7. MECHANICAL SYSTEM TESTS
(a) Measure the stall speed. The object of this test is to check the overall performance of the transmis\
sion and engine by measuring
the stall speeds in the D and R positions.
NOTICE:
Do the that at normal operating ATF temperature 50 − 80°C (122 − 176° F).
Do not continuously run this test longer than 5 seconds.
To ensure safety, conduct this test in a wide, clear, level area which provides good traction.
The stall test should always be carried out in pairs. One technician should\
observe the condi-
tions of wheels or wheel stoppers outside the vehicle while the other is doin\
g the test.
(1) Chock the 4 wheels.
(2) Connect an OBD II scan tool or TOYOTA hand−held tester to the DLC3.
(3) Fully apply the parking brake.
(4) Keep your left foot pressed firmly on the brake pedal.
(5) Start the engine.
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DI5OA−02
−
DIAGNOSTICS CRUISE CONTROL SYSTEM
DI−295
1996 LAND CRUISER (RM451U)
PROBLEM SYMPTOMS TABLE
SymptomSuspect AreaSee page
SET not occourring or CANCEL occurring.
(DTC is Normal)
1. Main Switch Circuit (Cruise control switch)
2. Vehicle Speed Sensor
3. Control Switch Circuit (Cruise control switch)
4. Stop Light Switch Circuit
5. Park/Neutral Position Switch Circuit
6. Actuator Motor Circuit
7. Cruise Control Cable
8. Cruise Control ECUDI−330
DI−306
DI−311
DI−314
DI−322
DI−296
DI−336 IN−28
SET not occurring or CANCEL occurring.
(DTC does not output)1. ECU Power Source Circuit
2. Cruise Control ECUDI−325IN−28
Actual vehicle speed deviates above or below the set speed.
1. Cruise Control Cable
2. Vehicle Speed Signal Abnormal
3. Electronically Controlled Transmission Communication
Circuit
4. Actuator Motor Circuit
5. Idle Signal Circuit (main throttle position sensor)
6. Cruise Control ECUDI−336
DI−310
DI−319
DI−296
DI−316IN−28
Gear shifting frequent between 3rd O/D when driving on uphill
road. (Hurting)1. Electronically Controlled Transmission Communication
Circuit
2. Cruise Control ECUDI−319
IN−28
Cruise control not cancelled, even when brake pedal is de-
pressed.
1. Cruise Control Cable
2. Stop Light Switch Circuit
3. Actuator Motor Circuit
4. Cruise Control ECUDI−336
DI−314
DI−296IN−28
Cruise control not cancelled, even when transmission is shifted to
”N” postion.
1. Cruise Control Cable
2. Park/Neutral Position Switch Circuit
3. Actuator Motor Circuit
4. Cruise Control ECUDI−336
DI−322
DI−296IN−28
Control switch does not operate.
(SET/COAST, A CC/RES, CANCEL not possible)
1. Cruise Control Cable
2. Control Switch Circuit
3. Actuator Motor Circuit
4. Cruise Control ECUDI−336
DI−311
DI−296 IN−28
SET possible at 40 km/h (25 mph) or less, or CANCEL does not
operate at 40 km/h (25 mph) or less.
1. Cruise Control Cable
2. Vehicle Speed Signal Abnormal
3. Actuator Motor Circuit
4. Cruise Control ECUDI−336
DI−310
DI−296IN−28
Poor response is ACCEL and RESUME modes.
1. Cruise Control Cable
2. Electronically Controlled Transmission Communication
Circuit
3. Actuator Motor Circuit
4. Cruise Control ECUDI−336
DI−319
DI−296IN−28
O/D does not RESUME, even though the road is not uphill.
1. Electronically Controlled Transmission Communication
Circuit
2. Cruise Control ECUDI−319
IN−28
DTC memory is erased.1. Back− up Power Source Circuit
2. Cruise Control ECUDI−328 IN−28
DTC is not output, or is output when is should not be.1. Diagnosis Circuit
2. Cruise Control ECUDI−319IN−28
Cruise MAIN indicator light remains ON or fall to light up.1. Cruise MAIN Indicator Light Switch CircuitDI−332
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