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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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Page 537 of 1399

A00184
STARTIGT
(+)(−)
BE6653
P24674
A00186
ON and START
3
BE6653
P24675
DI−100
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
6 Disconnect igniter connector and check voltage between terminals IGT of ECM
connector and body ground.
PREPARATION:
(a) Disconnect igniter connector.
(b) Remove instrument panel speaker No.1 panel (See page
SF−65 ).
CHECK:
Measure voltage between terminal IGT of ECM connector and
body ground when engine is cranked.
OK:
Voltage: More than 0.1 V and less than 4.5 V
OK Check and replace ECM (See page IN−28 ).
NG
7 Check voltage between terminal 3 of igniter connector and body ground.
PREPARATION:
Disconnect igniter connector.
CHECK:
Measure voltage between terminal 3 of igniter connector and
body ground, when ignition switch is turned to ”ON” and
”START” position.
OK:
Voltage: 9 − 14 V
NG Check and repair igniter power source circuit.
OK
8 Check for open and short in harness and connector between ignition switc\
h and ignition coil, ignition coil and igniter (See page IN−28).
NG Repair or replace harness or connector.
OK
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−
DIAGNOSTICS ENGINE
DI−101
1996 LAND CRUISER (RM451U)
9 Check ignition coil (See page IG−1).
NG Replace ignition coil.
OK
Replace igniter.
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S00816
BatteryFusible
Link
F8F7
11
W−R
3EA2
W−R11 6
IG Switch B−R
Fuse BlockIGN B−L
22
22 2
2
EFI Main Relay
1
2
3 4
EFI R
−Y
EC
EB
B−R
1EB1
R
Y−R
Y−REA2IH1
22 7
BR−B E4
E7 E7 E7
IGSW
MRLY
+B
E1 B+
ECM
1
3
12
24FL AM2
FL MAIN
W R
R/B No.2 Y
DI−11 0
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
ECM Power Source Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned ON, battery positive voltage is applied t\
o the coil, closing the contacts of
the EFI main relay (Marking: EFI) and supplying power to the terminals +B\
of the ECM.
WIRING DIAGRAM
DI5PX−02
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P22480
BatteryStarter
FL MAIN
FL AM2EFI
EFI Main Relay
IG Switch IG
ST
Park/Neutral
Position SwitchCircuit Opening
Relay
Fuel Pump Relay
Fuel Pump
From Crankshaft Position
Sensor Fuel Pump
Resistor
(STA Signal)
(NE Signal) MRLY
FC
STA
NE
Tr1
Tr2
ECM
IGN FPR
−
DIAGNOSTICS ENGINE
DI−11 5
1996 LAND CRUISER (RM451U)
Fuel Pump Control Circuit
CIRCUIT DESCRIPTION
In the diagram below, when the engine is cranked, current flows form terminal ST of the igni\
tion switch to
terminal STA of ECM (STA signal).
When the STA signal and NE signal are input to the ECM, Tr1 is turned ON, current flows to coil of the circuit
opening relay, the relay switches on, power is supplied to the fuel pump and the fuel\
pump operates.
While the NE signal is generated (engine running), the ECM keeps Tr1 ON (circuit opening relay ON) and
the fuel pump also keeps operating.
The fuel pump speed is controlled at 2 levels (high speed or low speed) b\
y the condition of the engine (start-
ing, light load, heavy load). When the engine starts (STA ON), Tr2 in the ECM is OFF, so battery voltage is
applied directry to the fuel pump. Fuel pump operates at high speed.
After the engine starts, during idling or light loads, since Tr2 goes ON, power is supplied to the fuel pump
via the fuel pump resistor.
Fuel pump operates at low speed.
DI5PY−02
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Q07308
AT3417
OK if hot
Add if hot
AT4252
0 − 1 mm
Q07309
DI−138
−
DIAGNOSTICS AUTOMATIC TRANSMISSION
1996 LAND CRUISER (RM451U)
(3) With the engine OFF, add new fluid through the oil
filler pipe.
Fluid type: ATF DEXRON ®II
Capacity:
Dry fill: 11.0 liters (11.6 US qts, 9.7 Imp. qts)
Drain and refill: 1.9 liters (2.0 US qts, 1.7 Imp. qts)
(4) Start the engine and shift the shift lever into all posi-
tions from P to L position and then shift into P posi-
tion.
(5) With the engine idling, check the fluid level. Add fluid up to the COOL level on the dipstick.
(6) Check the fluid level at the normal operating tem- perature 70 − 80° C (158 − 176°F) and add as nec-
essary.
NOTICE:
Do not overfill.
(d) Check the fluid leaks.
Check for leaks in the transmission.
If there are leaks, it is necessary to repair or replace O −rings,
Seal packings, oil seals, plugs or other parts.
(e) Inspect and adjust the throttle cable. (1) Check that the throttle valve is fully closed.
(2) Check that the inner cable is not slack.
(3) Measure the distance between the outer cable endand stopper on the cable.
Standard distance: 0 − 1 mm (0 − 0.04 in.)
If the distance is not standard, adjust the cable by the adjusting
nuts.
(f) Inspect and adjust the shift lever position. When shifting the shift lever from the N position to other
positions, check that the lever can be shifted smoothly
and accurately to each position and that the position indi-
cator correctly indicates the position.
If the indicator is not aligned with the correct position, carry out
the following adjustment procedures. (1) Loosen the nut on the control rod.
(2) Push the control rod fully rearward.
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Page 578 of 1399

−
DIAGNOSTICS AUTOMATIC TRANSMISSION
DI−141
1996 LAND CRUISER (RM451U)
8. HYDRAULIC TEST
Measure the line pressure.
NOTICE:
Do the test at normal operation ATF temperature 50 − 80°C (122 − 176° F).
The line pressure test should always be carried out in pairs. One techni\
cian should observe
the conditions of wheels or wheel stoppers outside the vehicle while the ot\
her is doing the test.
Be careful to prevent SST’s hose from interfering with the exhaust pipe.
(1) Warm up the ATF.
(2) Remove the test plug on the transmission case right side and connect SST\
(See page AT−18
for the location to connect SST).
SST 09992 −00094 (09992 −00150, 09992−00270)
(3) Fully apply the parking brake and chock the 4 wheels.
(4) Start the engine and check idling speed.
(5) Keep your left foot pressed firmly on the brake pedal and shift into D p\
osition.
(6) Measure the line pressure when the engine is idling.
(7) Press the accelerator pedal all the way down. Quickly read the highest line pr\
essure when engine
speed reaches stall speed.
NOTICE:
Release the accelerator pedal and stop test if the rear wheels begin to rotate before the engine speed
reaches the specified stall speed.
(8) In the same manner, do the test in R position.
Specified line pressure:
Condition D position kPa (kgf/cm2, psi) R position kPa (kgf/cm2, psi)
Idling422 −
481 (4.3 − 4.9, 61 − 70)510 − 608 (5.2 − 6.2, 74 − 88)
Stall1,285 − 1,530 (13.1 − 15.6, 128 − 153)1,579 − 1,932 (16.1 − 19.7, 158 − 193)
If the measured pressures are not up to specified values, recheck the thro\
ttle cable adjustment and retest.
Evaluation:
ProblemPossible cause
If the measured value at all positions are higher
Throttle cable out of adjustment
Throttle valve defective
Regulator valve defective
If the measured value at all positions are lower
Throttle cable out of adjustment
Throttle valve defective
Regulator valve defective
Oil pump defective
O/D direct clutch defective
If pressure is low in the D position onlyD position circuit fluid leakage
Forward clutch defective
If pressure is low in the R position only
R position circuit fluid leakage
Direct clutch defective
1st and reverse brake defective
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