1996 TOYOTA LAND CRUISER air condition

DI−12
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
(b) TOYOTA Enhanced Signals.
TOYOTA hand−held tester displayMeasurement ItemNormal Condition*
MISFIRE RPMEngine RPM for first misfire rangeMisfire 0: 0 rpm
MISFIRE LOADEngine load for first misfire rangeMisfire 0: 0 g/r
INJECTORFuel injection time for cylinder No.1Idling: 2.0 − 3.5 ms
IAC STEP POSIntake Air Control Valve step position
Opening position step motor type IAC valveIdling: 10 − 50 step
STARTER SIGStarter SignalCranking: ON
CTP SWClosed Throttle Position Switch SignalThrottle Fully Closed: ON
A/C SIGA/C Switch SignalA/C ON: ON
PNP SWPark/Neutral Position Switch SignalP or N Position: ON
STOP LIGHT SWStop Light Switch SignalStop light switch ON: ON
FC IDLFuel Cut Idle: Fuel cut when throttle valve fully
closed, during decelerationFuel cut operating: ON
FC TAUFuel Cut TAU: Fuel cut during very light loadFuel cut operating: ON
CYL#1 − CYL#6Ratio of revolution variation for each cylinder
when variation is large0%
IGNITIONIgnition rate for all cylinders every 1,000 revolu-
tions0 − 3,000 rpm
EGRT GASEGR Gas Temp. Sensor V alueEGR not operating: Temp. between intake air
temp. and engine coolant temp.
EGR SYSTEMEGR System Operating ConditionIdling: OFF
FUEL PRES UP VSVFuel Pressure Up VSV SignalHigh temp. restarting: ON
FUEL PUMPFuel Pump SignalIdling: ON
TOTAL FT B1Total Fuel Trim Bank 1: Average value for fuel
trim system of bank 1Idling: 0.8 − 1.2 V
O2 LR B1, S1
Oxygen Sensor Lean Rich Bank 1, Sensor 1
Response time for oxygen sensor output to
switch from lean to rich
Idling after warmed up: 0 − 1,000 msec.
O2 RL B1, S1
Oxygen Sensor Rich Lean Bank 1, Sensor 1
Response time for oxygen sensor output to
switch from rich to lean
Idling after warmed up: 0 − 1,000 msec.
∗: If no conditions are specifically stated for ”ldling”, it means t\
he shift lever is at N or P position, the A/C switch
is OFF and all accessory switches are OFF.
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DI5OX−03
FI6526
12345678910
11
1213
1415161718192021222324252612345678
910
11
1213141516 123456
78
910
11
12 12345678910
11
1415161718192021221213
E4 E5E6 E7
ECM Terminals
−
DIAGNOSTICS ENGINE
DI−17
1996 LAND CRUISER (RM451U)
TERMINALS OF ECM
Symbols (Terminals No.)Wiring ColorConditionSTD Voltage (V)
BATT (E7 − 2) − E1 (E4 − 24)R − Y ↔ BR − BAlways9 − 14
+ B (E7 − 12) − E1 (E4 − 24)Y ↔ BR − BIG switch ON9 − 14
VCC (E5 − 1) − E2 (E5 − 9)R − G ↔ BR − BIG switch ON4.5 − 5.5
IDL (E5 − 11) − E2 (E5 − 9)G − W ↔ BR − B
IG switch ON and apply vacuum to the throttle opener
Throttle valve fully closed0 − 3
IG switch ON
Throttle valve fully open9 − 14
VTA (E5 − 10) − E2 (E5 − 9)G − B↔ BR − B
IG switch ON
Throttle valve fully closed0.3 − 0.8
IG switch ON
Throttle valve fully open3.2 − 4.9
VG (E5 − 2) − E21 (E5 − 16)G − BRIdling, N position, A/C switch OFF1.1 − 1.5
THA (E5 − 3) − E2 (E5 − 9)L − Y ↔ BR − BIdling, Intake air temp. 20° C (68° F)0.5 − 3.4
THW (E5 − 4) − E2 (E5 − 9) R − W↔BR − BIdling, Engine coolant temp. 80 °C (176°F)0.2 − 1.0
STA (E7 − 11) − E1 (E4 − 24)B − R ↔ BR − BCranking6.0 or more
#10 (E4 − 12) − E01 (E4 − 13)W − L ↔ BR
IG switch ON9 − 14
IdlingPulse generation
(See page DI−54)
#20 (E4 − 11) − E01 (E4 − 13)W − R ↔ BR
IG switch ON9 − 14
IdlingPulse generation
(See page DI−54)
#30 (E4 − 25) − E01 (E4 − 13)W − G ↔ BR
IG switch ON9 − 14
IdlingPulse generation
(See page DI−54)
#40 (E4 − 2) − E01 (E4 − 13)Y ↔ BR
IG switch ON9 − 14
IdlingPulse generation
(See page DI−54)
#50 (E4 − 1) − E01 (E4 − 13)Y − R ↔ BR
IG switch ON9 − 14
IdlingPulse generation
(See page DI−54)
#60 (E4 − 15) − E01 (E4 − 13)Y − L ↔ BR
IG switch ON9 − 14
IdlingPulse generation
(See page DI−54)
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DI5OZ−02
A00152
Output Voltage
Power Transistor
B+
Thermistor
Platinum Hot Wire
A B
Thermistor Platinum Hot Wire
FI6929 P22263
DI−20
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
CIRCUIT INSPECTION
DTC P0100 Mass Air Flow Circuit Malfunction
CIRCUIT DESCRIPTION
The mass air flow meter uses a platinum hot wire. The hot wire air flow met\
er consists of a platinum hot wire,
thermistor and a control circuit installed in a plastic housing. The hot wire air f\
low meter works on the principle
that the hot wire and thermistor located in the intake air bypass of the hou\
sing detect any changes in the
intake air temperature.
The hot wire is maintained at the set temperature by controlling the curren\
t flow through the hot wire. This
current flow is then measured as the output voltage of the air flow mete\
r.
The circuit is constructed so that the platinum hot wire and thermistor pro\
vide a bridge circuit, with the power
transistor controlled so that the potential of ”A” and ”B” remains equ\
al to maintain the set temperature.
DTC No.DTC Detecting ConditionTrouble Area
P0100Open or short in mass air flow meter circuit with engine
speed 4,000 rpm or less. Open or short in mass air flow meter circuit
 Mass air flow meter
 ECM
If the ECM detects DTC” P0100” it operates the fail safe function, k\
eeping the ignition timing and injection
volume constant and marking it possible to drive the vehicle.
HINT:
After confirming DTC P0100 use the OBD II scan tool or TOYOTA hand −held tester to confirm the mass air
flow ratio from ”CURRENT DATA”.
Mass Air Flow Value (gm/sec.)Malfunction
Approx. 0Mass air flow meter power source open
 VG circuit open or short
439.0 or moreE21 circuit open
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−
DIAGNOSTICS ENGINE
DI−25
1996 LAND CRUISER (RM451U)
DTC P0101 Mass Air Flow Circuit Range/Performance
Problem
CIRCUIT DESCRIPTION
Refer to DTC P0100 (Mass Air Flow Circuit Malfunction) on page DI−20.
DTC No.DTC Detecting ConditionTrouble Area
P0101
Conditions (a) and (b) continue with engine speed 900 rpm or
less (2 trip detection logic):
(a) Closed throttle position switch: ON
(b) Mass air flow meter output > 2.2 V
Mass air flow meterConditions (a) and (b) continue with engine speed 1500 rpm
(2 trip detection logic):
(a) Mass air flow meter output < 1 V
(b) VTA  0.72 V
WIRING DIAGRAM
Refer to DTC P0100 (Mass Air Flow Circuit Malfunction) on page DI−20 for the WIRING DIAGRAM.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0101) being output?
YES Go to relevant DTC chart.
NO
Replace mass air flow meter.
DI5P0−02
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FI4741
(fig.1)Acceptable
Resistance kΩ
− 20 0 20 40 60 80 100
( − 4) 32 68 104 140 176 212
30
20
10
53
2
1
0.5
0.3
0.2
0.1
Temp. °C (F °)
DI−26
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
DTC P0110 Intake Air Temp. Circuit Malfunction
CIRCUIT DESCRIPTION
The intake air temperature sensor is built into the air flow meter
and senses the intake air temperature.
A thermistor built in the sensor changes the resistance value
according to the intake air temperature. The lower the intake air
temperature, the greater the thermistor resistance value, and
the higher the intake air temperature, the lower the thermistor
resistance value (See fig.1).
The intake air temperature sensor is connected to the ECM
(See next page). The 5 V power source voltage in the ECM is
applied to the intake air temperature sensor from the terminal
THA via a resistor R.
That is, the resistor R and the intake air temperature sensor are
connected in series. When the resistance value of the intake air
temperature sensor changes in accordance with changes in the
intake air temperature, the potential at terminal THA also
changes. Based on this signal, the ECM increases the fuel in-
jection volume to improve driveability during cold engine opera-
tion.
If the ECM detects the DTC ”P0110”, it operates the fail safe
function in which the intake air temperature is assumed to be
20 °C (68 °F).
Intake Air Temp.
° C (° F)Resistance
(kΩ)Voltage
(V)
−20 (− 4)16.24.3
0 (32)5.93.4
20 (68)2.52.4
40 (104)1.11.4
60 (140)0.60.9
80 (176)0.30.5
100 (212)0.10.2
DTC No.DTC Detecting ConditionTrouble Area
P0110Open or short in intake air temp. sensor circuit
Open or short in intake air temp. sensor circuit
 Intake air temp. sensor
 ECM
HINT:
After confirming DTC P110 use the OBD II scan tool or TOYOTA hand −held tester to confirm the intake air
temp. from ”CURRENT DATA”.
Temp. DisplayedMalfunction
− 40° C (− 40°F)Open circuit
140°C (284°F) or moreShort circuit
DI5P1−02
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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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P21242 FI7210A00027
Atmosphere
Flange
Platinum Electrode
Solid Electrolyte
(Zirconia Element)
Platinum Electrode
Heater
Coating (Ceramic)
Exhaust GasCover Ideal Air−
Fuel Mixture
Output Voltage
Richer − Air Fuel Ratio − Leaner
DI−40
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of th\
e exhaust gas, a three −way cata-
lytic converter is used, but for the most efficient use of the three −way catalytic converter, the air−fuel ratio
must be precisely controlled so that it is always close to the stoichiom\
etric air −fuel ratio.
The oxygen sensor has the characteristic where by its output voltage change\
s suddenly in the vicinity of the
stoichiometric air −fuel ratio. This characteristic is used to detect the oxygen concentrati\
on in the exhaust
gas and provide feedback to the computer for control of the air −fuel ratio.
When the air −fuel ratio becomes LEAN, the oxygen concentration in the exhaust increas\
es and the oxygen
sensor informs the ECM of the LEAN condition (small electromotive force: 0 V)\
.
When the air −fuel ratio is RICHER than the stoichiometric air −fuel ratio the oxygen concentration in the ex-
haust gas in reduced and the oxygen sensor informs the ECM of the RICH condit\
ion (large electromotive
force: 1 V). The ECM judges by the electromotive force from the oxygen \
sensor whether the air −fuel ratio
is RICH or LEAN and controls the injection time accordingly. However, if malfunction of the oxygen sensor
causes output of abnormal electromotive force, the ECM is unable to perform acc\
urate air −fuel ratio control.
The heated oxygen sensors include a heater which heats the zirconia element\
. The heater is controlled by
the ECM. When the intake air volume is low (the temp. of the exhaust gas i\
s low) current flows to the heater
to heat the sensor for accurate oxygen concentration detection.
DTC No.DTC Detecting ConditionTrouble Area
P0125
After the engine is warmed up, heated oxygen sensor (bank 1
sensor 2) output does not indicate RICH even once when
conditions (a), (b) and (c) continue for at least 1.5 min.
(a) Engine speed: 1,500 rpm or more
(b) Vehicle speed: 40 − 100 km/h (25 − 62 mph)
(c) Closed throttle position switch: OFF
 Open or short in heated oxygen sensor (bank 1 sensor 1)
circuit
 Heated oxygen sensor (bank1 sensor 1)
DI5P9−02
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DI−44
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
INSPECTION PROCEDURE
1 Check for open and short in harness and connector between ECM and heated
oxygen sensor (bank 1 sensor 1) (See page IN−28 ).
NG Repair or replace harness or connector
(See page IN−28 ).
OK
2 Check for heated oxygen sensor (bank 1 sensor 1) data.
PREPARATION:
(a) Remove the fuse cover on the instrument panel.
(b) Connect the OBD II scan tool or TOYOTA hand−held tester to the DLC3.
(c) Warm up engine to normal operating temp.
CHECK:
Read the heated oxygen sensor (bank 1 sensor 1) output voltage and sho\
rt −term fuel trim.
RESULT:
PatternHeated o xygen sensor (bank 1 sensor 1) output voltageShort−term fuel trim
1Lean condition (Changes at 0.55 V or less)Changes at about +20 %
2Rich condition (Changes at 0.4 V or more)Changes at about −20 %
3Except 1 and 2
1, 2 Check fuel trim system (See page DI−51 ).
3
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