1996 TOYOTA LAND CRUISER Land Cruiser 80

P22417
Exhaust
Gas
Intake Air
Chamber EGR
Valve
VSV
EGR
Vacuum
Modulator
ECM
Throttle
valve
P22426
BR
From Battery R/B No.2
R−Y
2
222
2
2
Y−R
EFI Main
Y−R
1
2
43
REA2
EZ1
EB12 7
VSV for EGR 21
YYL
−W
EZ14
EGR Gas T emp.
Sensor
21
G−Y
BR−BE7 E4
E4
E5 3
22
19
9
THG
E1
EGR
E2 5V
MRLY
ECM
R
EB
EFI
1
Relay
B+
E01
−
DIAGNOSTICS ENGINE
DI−69
1996 LAND CRUISER (RM451U)
DTC P0401 Exhaust Gas Recirculation Flow Insufficient
Detected
CIRCUIT DESCRIPTION
The EGR system recirculates exhaust gas, which is controlled to the proper \
quantity to suit the driving condi-
tions, into the intake air mixture to slow down combustion, reduce the combust\
ion temp. and reduce NOx
emissions. The amount of EGR is regulated by the EGR vacuum modulator ac\
cording to the engine load.
If even one of the following conditions is fulfilled, the VSV is
turned ON by a signal from the ECM.
This results in atmospheric air acting on the EGR valve, closing
the EGR valve and shutting off the exhaust gas (EGR cut− off).
Under the following conditions, EGR is cut to maintain driveabil-
ity.
Before the engine is warmed up.
During deceleration (throttle valve closed).
Light engine load (amount of intake air very small).
Engine racing.
DTC No.DTC Detecting ConditionTrouble Area
P0401
After the engine is warmed up and run at 80 km/h (50 mph)
for 3 to 5 minutes, the EGR gas temperature sensor value
does not exceed 38° C (100.4°F) above the ambient air tem-
perature. (2 trip detection logic) EGR valve stuck closed
 Short in VSV circuit for EGR
 Open in EGR gas temp. sensor circuit
 EGR hose disconnected
 ECM
WIRING DIAGRAM
DI5PK−02
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P20769
(43 − 56 mph)
Vehicle Speed
70 − 90 km/h
Idling
IG SW OFF (1)(2) (3)
(4) (6)
(5)
Warm up 3 − 5 min. 2 min.
3 − 5 min.2 min.(7)
Time
DI−70
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
SYSTEM CHECK DRIVING PATTERN
(1) Connect the OBD II scan tool or TOYOTA hand −held tester to the DLC3.
(2) Start and warm up the engine with all accessories switched OFF.
(3) Run the vehicle at 70 − 90 km/h (43 − 56 mph) for 3 min. or more.
(4) Idle the engine for about 2 min.
(5) Stop at safe place and turn the ignition switch OFF.
(6) Start the engine and do steps (3) and (4) again.
(7) Check the ”READINESS TESTS” mode on the OBD II scan tool or\
TOYOTA hand−held tester.
If ”COMPL” is displayed and the MIL does not light up, the system \
is normal.
If ”INCMPL” is displayed and the MIL does not light up, run the ve\
hicle again and check it.
HINT:
”INCMPL” is displayed when either condition (a) or (b) exists.\
(a) The system check is incomplete.
(b) There is a malfunction in the system.
If there is a malfunction in the system, the MIL will light up after ste\
ps (2) to (6) above are done.
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A00168
ON
EGR Gas Temp.
Sensor ECM
19 9
1
2
BE6653
FI7055 THG
E2
E4
E5 5V
−
DIAGNOSTICS ENGINE
DI−71
1996 LAND CRUISER (RM451U)
INSPECTION PROCEDURE
TOYOTA hand −held tester
1 Connect the TOYOTA hand −held tester and read value of EGR gas temp. value.
PREPARATION:
(a) Remove the fuse cover on the instrument panel.
(b) Connect the TOYOTA hand−held tester to the DLC3.
(c) Turn ignition switch ON and push the TOYOTA hand −held tester main switch ON.
CHECK:
Read EGR gas temp. on the TOYOTA hand−held tester.
OK:
EGR gas temp.: 10° C (50°F) or more
HINT:
If there is and open circuit, the TOYOTA hand−held tester indicates 3.1 °C (37.6° F).
OK Go to step 4.
NG
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the EGR gas temp. sensor connector.
(b) Connect sensor wire harness terminals together.
(c) Turn ignition switch ON.
CHECK:
Read EGR gas temp. on the TOYOTA hand−held tester.
OK:
EGR gas temp.: Approx. 157.5° C (315.5°F)
OK Confirm good connection at sensor. If OK, replace EGR gas temp. sensor.
NG
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A00169
ON
EGR Gas Temp.
Sensor ECM
1
2 19
9
THG E2
BE6653
FI7057
P22167 E4
E5
THG E2 5V
DI−72
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
3 Check for open in harness or ECM.
PREPARATION:
(a) Remove the instrument panel speaker No.1 panel (See
page SF−65 ).
(b) Connect between terminals THG and E2 of ECM connec-
tor.
HINT:
EGR gas temp. sensor connector is disconnected.
Before checking, do a visual check and contact pressure check
for the ECM connector (See page IN−28).
CHECK:
Read EGR gas temp. on the TOYOTA hand−held tester.
OK:
EGR gas temp.: Approx. 157.5° C (315.5°F)
OK Open in harness between terminals E2 or THG. Repair or replace harness.
NG
Confirm connection at ECM.
If OK, replace ECM (See page IN−28).
4 Check the connection of the vacuum hose, EGR hose (See page EC−11).
NG Repair or replace.
OK
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A00170
System : ON
System : OFF Air
GE
Air GE
P22963
P22964
−
DIAGNOSTICS ENGINE
DI−73
1996 LAND CRUISER (RM451U)
5 Check the VSV for EGR.
PREPARATION:
(a) Remove the fuse cover on the instrument panel.
(b) Connect the TOYOTA hand−held tester to the DLC3.
(c) Turn ignition switch ON and TOYOTA hand −held tester
main switch ON.
(d) Select the ACTIVE TEST mode on the TOYOTA hand −
held tester.
CHECK:
Check operation of VSV, when it is operated by the TOYOTA
hand −held tester.
OK:
EGR system is ON:
Air does not flow from pipe G to pipe E.
EGR system is OFF:
Air from pipe G is flowing out through pipe E.
OK Go to step 7.
NG
6 Check operation of the VSV for EGR (See page SF−60).
NG Replace VSV for EGR.
OK
Check for open in harness and connector be-
tween VSV and ECM (See page IN−28).
7 Check EGR vacuum modulator (See page EC−11 ).
NG Repair or replace.
OK
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DI−74
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
8 Check EGR valve (See page EC−11).
NG Repair or replace.
OK
9 Check value of EGR gas temp. sensor.
PREPARATION:
(a) Remove the fuse cover on the instrument panel.
(b) Connect the TOYOTA hand−held tester to the DLC3.
(c) Turn ignition switch ON and TOYOTA hand −held tester main switch ON.
(d) Select the ACTIVE TEST mode on the TOYOTA hand−held tester. (EGR system ON)
(e) Race the engine at 4,000 rpm for 3 mins.
CHECK:
Measure the EGR gas temp. while racing engine at 4,000 rpm.
OK:
EGR gas temp. after 3 mins.: 140° C (284°F) or more
NG Replace EGR gas temp. sensor.
OK
Check and replace ECM (See page IN−28 ).
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P24665
A00171
ON(−)(+)
BE6653
P22896
P24666
−
DIAGNOSTICS ENGINE
DI−75
1996 LAND CRUISER (RM451U)
OBD II scan tool (excluding TOYOTA hand −held tester)
1 Check resistance of EGR gas temp. sensor.
PREPARATION:
Disconnect EGR gas temp. sensor connector.
CHECK:
Measure resistance between terminals of EGR gas temp. sen-
sor connector.
OK:
Resistance: 600 k Ω or less
HINT:
If there is open circuit, ohmmeter indicates 720 k Ω or more.
NG Check and replace EGR gas temp. sensor (See page SF−63 ).
OK
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect EGR gas temp. sensor connector.
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminals of EGR gas temp. sensor
wire harness side connector.
OK:
Voltage: 4.5 − 5.5 V
OK Go to step 4.
NG
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A00172
ON
THG E2 (+)(−)
BE6653
P24667
DI−76
−
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) Turn ignition switch ON.
CHECK:
Measure voltage between terminals of THG and E2 of ECM
connector.
HINT:
EGR gas temp. sensor connector is disconnected.
OK:
Voltage: 4.5 − 5.5 V
OK Open in harness between terminals E2 or THG. Repair or replace harness.
NG
Confirm connection at ECM.
If OK, replace ECM (See page IN−28).
4 Check connection of vacuum hose, EGR hose (See page EC−11).
NG Repair or replace.
OK
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