1996 TOYOTA LAND CRUISER air condition

P23431
Waveform of Oxygen Sensor
Before CatalystNormal
CatalystWaveform of Oxygen Sensor
After Catalyst
DI−84
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
DTC P0420 Catalyst System Efficiency Below Threshold
CIRCUIT DESCRIPTION
The ECM compares the waveform of the oxygen sensor located before the catal\
yst with the waveform of
the oxygen sensor located after the catalyst to determine whether or not ca\
talyst performance has deterio-
rated.
Air−fuel ratio feedback compensation keeps the waveform of the oxygen sensor\
before the catalyst repeat-
edly changing back and forth from rich to lean.
If the catalyst is functioning normally, the waveform of the oxygen sensor after the catalyst switches back
and forth between rich and lean much more slowly than the waveform of the o\
xygen sensor before the cata-
lyst.
But when both waveforms change at a similar rate, it indicates that catalyst perf\
ormance has deteriorated.


DTC No.DTC Detecting ConditionTrouble Area
P0420
After the engine is warmed up and the vehicle driven for 6
mins. at 30 − 83 km/h (19 − 52 mph), the waveforms of the
heated oxygen sensors, bank 1 sensor 1 and bank1 sensor 2,
have the same amplitude Front exhaust pipe (front catalyst) and rear TWC (rear cata-
lyst)
 Heated oxygen sensor
DI5PM−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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−
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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P22477
BatteryFusible Link
E8
1 W
2 2
EFI
R/B No.2
R−YR−Y
EA2E7ECM
BATT
2
FL MAIN
2
−
DIAGNOSTICS ENGINE
DI−105
1996 LAND CRUISER (RM451U)
DTC P1600 ECM BATT Malfunction
CIRCUIT DESCRIPTION
Battery positive voltage is supplied to terminal BATT of the ECM even when the ignition switch is OFF for
use by the DTC memory and air −fuel ratio adaptive control value memory, etc.
DTC No.DTC Detecting ConditionTrouble Area
P1600Open in back up power source circuitOpen in back up power source circuit
 ECM
HINT:
If DTC P1600 appear, the ECM does not store another DTC.
WIRING DIAGRAM
DI5PT−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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Q08634
TOYOTA Hand−held Tester
DLC3
FI3605
ON
OFF 0.13 sec.
Flashing
−
DIAGNOSTICS AUTOMATIC TRANSMISSION
DI−133
1996 LAND CRUISER (RM451U)
(4) Use the OBD II scan tool or TOYOTA hand−held
tester to check the DTCs and freeze frame data.
Note them down (For operating instructions, see
the OBD II scan tool’s instruction book).
(5) See page DI−143 to confirm the details of the
DTCs.
NOTICE:
When simulating symptoms with an OBD II scan tool (ex-
cluding TOYOTA hand −held tester) to check the DTCs, use
the normal mode. For codes on the DTC chart subject to ”2
trip detection logic”, turn the ignition switch off after the
symptoms have been simulated for the 1st time. Them re-
peat the simulation process again. When the program has
been simulated twice, the MIL lights up and the DTCs are
recorded in the ECM.
3. Check Mode: INSPECT DIAGNOSIS
HINT:
TOYOTA hand−held tester only:
Compared to the normal mode, the check mode has high sens-
ing ability to detect malfunctions. Furthermore, the same diag-
nostic items which are detected in the normal mode can also be
detected in check mode.
(a) Check the DTC. (1) Check the initial conditions.
Battery positive voltage 11 V or more.
Throttle valve fully closed.
Transmission in P position.
Air conditioning switched off.
(2) Turn the ignition switch OFF.
(3) Prepare the TOYOTA hand−held tester.
(4) Connect the TOYOTA hand− held tester to the
DLC3 in the fuse box at the lower left of the instru-
ment panel.
(5) Turn the ignition switch ON and switch the T OYOTA
hand −held tester ON.
(6) Switch the TOYOTA hand −held tester from the nor-
mal mode to the check mode (Check that the MIL
flashes).
(7) Start the engine (The MIL goes).
(8) Simulate the conditions of the malfunction de- scribed by the customer.
NOTICE:
Leave the ignition switch ON until you have checked the
DTCs etc.
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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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DI−140
−
DIAGNOSTICS AUTOMATIC TRANSMISSION
1996 LAND CRUISER (RM451U)
(6) Shift into the D position. Press all the way down on the accelerator pedal wi\
th your right foot.
Quickly read the stall speed at this time.
Stall speed: 1,950 ± 150 rpm
(7) Do the same test in R position.
Stall speed: 1,950 ± 150 rpm
Evaluation:
ProblemPossible cause
Stall speed low in D and R positions
 Engine output may be insuf ficient
 Stator one− way clutch is operating properly
HINT:
If more than 600 rpm below the specified value, the torque con-
verter clutch could be faulty.
Stall speed high in D position
 Line pressure too low
 Forward clutch slipping
 No. 2 one− way clutch not operating properly
 O/D one− way clutch not operating properly
Stall speed high in R position
Line pressure too low
 Direct clutch slipping
 1st and reverse brake slipping
 O/D clutch slipping
Stall speed high in D and R positions
Line pressure too low
 Improper fluid level
 O/D one− way clutch not operating properly
(b) Measure the time lag.
When the shift lever is shifted while the engine is idling, there will be a certain time lapse o\
r lag before
the shock can be felt. This is used for checking the condition of the O/D d\
irect clutch, forward clutch,
direct clutch and 1st and reverse brake.
NOTICE:
Do the test at normal operating ATF temperature 50 − 80°C (122 − 176° F).
Be sure to allow 1 minute interval between tests.
Take 3 measurements and take the average value.
(1) Fully apply the parking brake.
(2) Start the engine and check idle speed.
Idle speed: 650 ± 50 rpm (In N position and air conditioner OFF)
(3) Shift the shift lever from N to D position. Using a stop watch, measure the ti\
me it takes from shift-
ing the lever until the shock is felt.
In the same manner, measure the time lag for N → R.
Time lag: N → D Less than 1.2 seconds
In the same way, measure the time lag for N → R.
Time lag: N → R Less than 1.5 seconds
If N → D time or N → R time lag is longer than specified:
Evaluation:
ProblemPossible cause
N → D time lag is longer
Line pressure too low
 Forward clutch worn
 O/D one− way clutch not operating properly
N → R time lag is longer
Line pressure too low
 Direct clutch worn
 1st and reverse brake worn
 O/D one− way clutch not operating properly
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