1996 TOYOTA LAND CRUISER Land Cruiser 80

A00173
ON
EGR ONOFF
(1) VSV is ON:
(2) VSV is OFF: Air
GE
Air GE
BE6653
P22905
P22963
P22964
−
DIAGNOSTICS ENGINE
DI−77
1996 LAND CRUISER (RM451U)
5 Check the VSV for EGR.
PREPARATION:
(a) Remove instrument panel speaker No.1 panel (See page
SF−65 ).
(b) Turn ignition switch ON.
CHECK:
Check VSV function.
(1) Connect between terminal EGR of ECM and bodyground (ON).
(2) Disconnect between terminal EGR of ECM and
body ground (OFF).
OK:
(1) VSV is ON:
Air does not flow from pipe G to pipe E.
(2) VSV is OFF:
Air from pipe G is flows out through pipe E.
OK Go to step 7.
NG
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DI−78
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
6 Check operation for the VSV for EGR (See page SF−60).
NG Replace VSV for EGR.
OK
Check for open in harness and connector be-
tween R/B No.2 and ECM (See page IN−28).
7 Check EGR vacuum modulator (See page EC−11 ).
NG Repair or replace.
OK
8 Check EGR valve (See page EC−11 ).
NG Repair or replace.
OK
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P24665
−
DIAGNOSTICS ENGINE
DI−79
1996 LAND CRUISER (RM451U)
9 Check resistance of EGR gas temp. sensor (See page SF−63).
PREPARATION:
(a) Disconnect EGR gas temp. sensor connector.
(b) Start the engine and warm it up.
(c) Disconnect VSV connector for EGR.
(d) Race the engine at 4,000 rpm or 3 mins.
CHECK:
Measure the resistance of the EGR gas temp. sensor while rac-
ing the engine at 4,000 rpm.
OK:
Resistance of EGR gas temp. sensor after 3 mins.:
4.3 kΩ or less
HINT:
At 20° C (68° F): 188.6 − 439.0 kΩ for resistance.
NG Replace EGR gas temp. sensor.
OK
Check and replace ECM (See page IN−28 ).
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DI−80
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
DTC P0402 Exhaust Gas Recirculation Flow Excessive Detected
CIRCUIT DESCRIPTION
Refer to DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) on page DI−69.
DTC No.DTC Detecting ConditionTrouble Area
P0402
EGR gas temp. sensor value is high during EGR cut −off when
engine is cold (Race engine at about 4,000 rpm without load so
that vacuum is applied to port E)
(2 trip detection logic) EGR valve stuck open
 EGR VSV open malfunction
 Open in VSV circuit for EGR
 Short in EGR gas temp. sensor circuit
 ECM
EGR valve is always open (2 trip detection logic)
Refer to DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) for the System Check Driving
Pattern and Wiring Diagram.
INSPECTION PROCEDURE
TOYOTA hand −held tester
1 Connect the TOYOTA hand −held tester and read 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.: 150° C (302°F) or less (Not immediately after driving)
HINT:
If there is a short circuit, the TOYOTA hand−held tester indicates Approx. 157.5°C (315.5°F).
OK Go to step 4.
NG
DI5PL−02
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A00174
ON
EGR Gas Temp.
Sensor 1
2 ECM
5V
E2
19
9
E4
E5 THG
BE6653
FI7054
A00175
ON
EGR Gas Temp.
Sensor ECM
5V
E2
E4 connector
THG
BE6653
FI7099
P22261
−
DIAGNOSTICS ENGINE
DI−81
1996 LAND CRUISER (RM451U)
2 Check for short in harness and ECM.
PREPARATION:
Disconnect the EGR gas temp. sensor connector.
CHECK:
Read EGR gas temp. on the TOYOTA hand−held tester.
OK:
EGR gas temp.: 3.1° C (37.6°F)
OK Replace EGR gas temp. sensor.
NG
3 Check for short in harness or ECM.
PREPARATION:
(a) Remove the instrument panel speaker No.1 panel. (See page SF−65 ).
(b) Disconnect the E4 connector of ECM.
HINT:
EGR gas temp. sensor is disconnected.
CHECK:
Read EGR gas temp. on the TOYOTA hand−held tester.
OK:
EGR gas temp.: 3.1° C (37.6°F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See page IN−28 ).
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P24665
DI−82
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
4 Check the VSV for EGR (See page DI−69 ).
OK Check EGR valve (See page EC−11).
NG
5 Check operation of the VSV for EGR (See page SF−60).
NG Replace VSV for EGR.
OK
Check for short in harness and connector
between VSV and ECM (See page IN−28).
OBD II scan tool (excluding TOYOTA hand −held tester)
1 Check resistance of EGR gas temp. sensor (See page DI−105).
PREPARATION:
Disconnect EGR gas temp. sensor connector.
CHECK:
Measure resistance between terminals of EGR gas temp. sen-
sor connector.
OK:
Resistance: 2.5 k Ω or more
(Not immediately after driving)
HINT:
If there is short circuit, ohmmeter indicates 200 Ω or less.
NG Replace EGR gas temp. sensor.
OK
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−
DIAGNOSTICS ENGINE
DI−83
1996 LAND CRUISER (RM451U)
2 Check for short in harness and connector between EGR gas temp. sensor and
ECM (See page IN−28 ).
NG Repair or replace harness or connector.
OK
3 Check the VSV for EGR (See page DI−69 , step 5).
OK Check EGR valve (See page EC−11).
NG
4 Check operation of the VSV for EGR (See page SF−60).
NG Replace VSV for EGR.
OK
5 Check for short in harness and connector between VSV and ECM (See page IN−28 ).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN−28 ).
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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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