1996 TOYOTA LAND CRUISER Workshop Manual

A00154
ON
Intake Air
Temp. Sensor ECM
5V
E2 E1
3
4 3
9
E5
E5
BE6653
FI7055 A00154 THA
A00150
ON
Intake Air
Temp. Sensor ECM
5V
3
9 E2
E1
THA E2
THA
E5
E5
BE6653
FI7057
P24655
DI−28
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the mass air flow meter connector.
(b) Connect sensor wire harness terminals together.
(c) Turn ignition switch ON.
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA hand −
held tester.
OK:
Temp. value: 140° C (284°F) or more
OK Confirm good connection at sensor. If OK, replace mass air flow meter.
NG
3 Check for open in harness or ECM.
PREPARATION:
(a) Remove instrument panel speaker No.1 panel (See page SF−65 ).
(b) Connect between terminals THA and E2 of ECM connec-
tor.
HINT:
Mass air flow meter connector is disconnected.
Before checking, do a visual and contact pressure check for the
ECM connector (See page IN−28).
(c) Turn ignition switch ON.
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA
hand −held tester.
OK:
Temp. value: 140° C (284°F) or more
OK Open in harness between terminals E2 or THA, repair or replace harness.
NG
Confirm good connection at ECM.
If OK, replace ECM (See page IN−28).
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A00151
ON
Intake Air
Temp. Sensor 3
4 ECM
3
9 5V
E2 E1
THA
E5
E5
BE6653
FI7054
A00155
ON
Intake Air
Temp. Sensor ECM
E5 connector 5V
E2 E1
THA
BE6653
FI7056
P19798
−
DIAGNOSTICS ENGINE
DI−29
1996 LAND CRUISER (RM451U)
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the mass air flow meter connector.
(b) Turn ignition switch ON.
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA hand −
held tester.
OK:
Temp. value: − 40° C (− 40°F)
OK Replace mass air flow meter.
NG
5 Check for short in harness or ECM.
PREPARATION:
(a) Remove instrument panel speaker No.1 panel (See page SF−65 ).
(b) Disconnect the E5 connector of ECM.
HINT:
Mass air flow meter connector is disconnected.
(c) Turn ignition switch ON.
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA hand −
held tester.
OK:
Temp. value: − 40°C (− 40 °F)
OK Repair or replace harness or connector (See page IN−28 ).
NG
Check and replace ECM (See page IN−28 ).
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A00485
Engine Coolant Temp. Sensor2
1 R−W
BR−B 5V
ECM
E5
E5
THW
E1
E2
4
9
P22421
DI−30
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
DTC P0115 Engine Coolant Temp. Circuit Malfunction
CIRCUIT DESCRIPTION
A thermistor built into the engine coolant temperature sensor changes the\
resistance value according to the
engine coolant temperature.
The structure of the sensor and connection to the ECM is the same as in the\
intake air temp. circuit malfunc-
tion shown on page DI−26.
If the ECM detects the DTC P0115, it operates the fail safe function in which the engine coolant temp.\
is
assumed to be 80 °C (176
°F).
DTC No.Detection ItemTrouble Area
P0115Open or short in engine coolant temp. sensor circuit
 Open or short in engine coolant temp. sensor circuit
 Engine coolant temp. sensor
 ECM
HINT:
After confirming DTC P0115 use the OBD II scan tool or TOYOTA hand −held tester to confirm the engine
coolant temp. from CURRENT DATA.
Temp. DisplayedMalfunction
− 40° C (− 40°F)Open circuit
140°C (284°F) or moreShort circuit
WIRING DIAGRAM
DI5P5−02
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A00156
ON
Engine Coolant
Temp. Sensor ECM
5V
4
9
2
1
E2
E1
THW
E5
E5
BE6653
FI7055
−
DIAGNOSTICS ENGINE
DI−31
1996 LAND CRUISER (RM451U)
INSPECTION PROCEDURE
HINT:
If DTC is 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.
1 Connect the OBD II scan tool or TOYOTA hand −held tester, and read value of
engine coolant temperature.
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) Turn ignition switch ON and push the OBD II scan tool or TOYOTA hand−held tester main switch ON.
CHECK:
Read temperature value on the OBD II scan tool or TOYOTA hand −held tester.
OK:
Same as actual engine coolant temperature.
HINT:
If there is open circuit, OBD II scan tool or TOYOTA hand−held tester indicates − 40°C (− 40 °F).
If there is short circuit, OBD II scan tool or T OYOTA hand−held tester indicates 140 °C (284 °F) or more.
NG −40°C ( −40° F) ... Go to step 2.
140 °C (284° F) or more ... Go to step 4.
OK
Check for intermittent problems
(See page DI−3 ).
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the engine coolant temp. sensor connector.
(b) Connect sensor wire harness terminals together.
(c) Turn ignition switch ON.
CHECK:
Read temp. value on the OBD II scan tool or TOYOTA hand −
held tester.
OK:
Temp. value: 140° C (284°F) or more
OK Confirm good connection at sensor. If OK, replace engine coolant temp. sensor.
NG
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A00157
ONECM
Engine Coolant
Temp. Sensor
5V
E2 E1
2
1
THW E2
THW
E5
E54
9
BE6653
FI7057
P24656
A00158
ON
Engine Coolant
Temp. Sensor ECM
5V
4
9 E2
E1
THW
BE6653
FI7054 E5
E5
DI−32
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
3 Check for open in harness or ECM.
PREPARATION:
(a) Remove instrument panel speaker No.1 panel
(See page SF−65 ).
(b) Connect between terminals THW and E2 of ECM connec-
tor.
HINT:
Engine coolant temp. sensor connector is disconnected. Be-
fore checking, do a visual and contact pressure check for the
ECM connector (See page IN−28).
(c) Turn ignition switch ON.
CHECK:
Read temperature value on the OBD II scan tool or TOYOTA
hand −held tester.
OK:
Temperature value: 140° C (284°F) or more
OK Open in harness between terminals E2 or THW, repair or replace harness.
NG
Confirm good connection at ECM.
If OK, replace ECM (See page IN−28).
4 Check for short in harness or ECM.
PREPARATION:
(a) Disconnect the engine coolant temp. sensor connector.
(b) Turn ignition switch ON.
CHECK:
Read temperature value on the OBD II scan tool or TOYOTA
hand−held tester.
OK:
Temperature value: − 40° C (− 40°F)
OK Replace engine coolant temp. sensor.
NG
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A00159
ON
Engine Coolant
Temp. Sensor ECM
5V
E2 E1
E5 connector
THW
BE6653
FI7056
P19798
−
DIAGNOSTICS ENGINE
DI−33
1996 LAND CRUISER (RM451U)
5 Check for short in harness or ECM.
PREPARATION:
(a) Remove instrument panel speaker No.1 panel
(See page SF−65 ).
(b) Disconnect the E5 connector of ECM.
HINT:
Engine coolant temp. sensor connector is disconnected.
(c) Turn ignition switch ON.
CHECK:
Read temperature value on the OBD II scan tool or TOYOTA
hand −held tester.
OK:
Temperature value: − 40° C (− 40°F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See page IN−28 ).
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DI−34
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
DTC P0116 Engine Coolant Temp. Circuit Range/ Performance Problem
CIRCUIT DESCRIPTION
Refer to DTC P0115 (Engine Coolant Temp. Circuit Malfunction) on page DI−30.
DTC No..DTC Detecting ConditionTrouble Area
P0116
If THW 10°C (50° F), 2 min. or more after starting engine,
engine coolant temp. sensor value is 35 °C (95° F) or less
(2 trip detection logic)
 Engine coolant temp. sensor
 Cooling system
If −7°C (19.4° F)  THW < 10 °C (50° F), 5 min. or more after
starting engine, engine coolant temp. sensor value 35 °C
(95 °F) or less
(2 trip detection logic)
If THW < −7°C (19.4° F), 20 min. or more after starting engine,
engine coolant temp. sensor value is 35 °C (95° F) or less
(2 trip detection logic)
INSPECTION PROCEDURE
HINT:
If DTC P0115 (Engine Coolant Temp. Circuit Malfunction) and P0116 (Engine Coolant Temp. Circuit Range/
Performance) are output simultaneously, engine coolant temp. sensor circuit may be open.
Perform troubleshooting of DTC P0115 first.
1 Are there any other codes (besides DTC P0116) being output?
YES Go to relevant DTC chart.
NO
2 Check thermostat (See page CO−9 ).
NG Replace the thermostat.
OK
Replace engine coolant temp. sensor.
DI5P6−02
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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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