1996 TOYOTA LAND CRUISER relay

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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P22474
EBBR
22 22
1 3
4
2 2
2
R−Y R/B No.2
From BatteryR
Y−R
EA2
EB1
Y−RY −R
Y−R R
R−G
R−B
G−Y
Y−L
4
1
3 6
IAC Valve MRLY
E7
E4
E4
E4
E4 7 3
6
5
4
ISC1
ISC2
ISC3
ISC4 B+
E01
E01
E01
E01
EFI
2
5
EFI Main
Relay
7
1 ECM
A00202
ISC1
ISC2
ISC3
ISC4 A/C Switch OFF
→ ON
(IAC Valve Open)
20 V/Division
10 msec./Division
ISC1
ISC2
ISC3
ISC4 20 V/
Division
10 msec./Division
(IAC Valve Close)
A/C Switch ON →
OFF
FI6536
FI6537
DI−90
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
WIRING DIAGRAM
Reference: INSPECTION USING OSCILLOSCOPE
With the engine idling measure wavefoms between terminals
ISC1, ISC2, ISC3, ISC4 and E01 of ECM when A/C switch ON
or OFF.
HINT:
The correct waveforms are as shown.
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A00178
ONISC1 ISC3ISC2 ISC4
E4 connector
(−) (+)
BE6653
P24669
−
DIAGNOSTICS ENGINE
DI−91
1996 LAND CRUISER (RM451U)
INSPECTION PROCEDURE
1 Check air induction system (See page SF−1 ).
NG Repair or replace.
OK
2 Check voltage terminals ISC1, ISC2, ISC3, ISC4, of ECM connector and bod\
y ground.
PREPARATION:
(a) Remove instrument panel speaker No.1 panel (See page
SF−65 ).
(b) Disconnect the E4 connector of ECM.
(c) Turn ignition switch ON.
CHECK:
Measure voltage between terminals ISC1, ISC2, ISC3, ISC4 of
ECM connector and body ground.
OK:
Voltage: 9 − 14 V
OK Go to step 4.
NG
3 Check IAC valve (See page SF−49 ).
NG Replace IAC valve.
OK
Check for open and short in harness and co −nnector between EFI main relay (Marking:EFI) and
IAC valve and ECM (See page IN−28).
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DI−104
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
INSPECTION PROCEDURE
HINT:
This diagnostic chart is based on the premise that the engine is cranked normally. If the engine is not
cranked, proceed to the matrix chart of problem symptoms on page DI−19.
1 Connect TOYOTA hand −held tester and check STA signal.
PREPARATION:
(a) Connect the TOYOTA hand−held tester to the DLC3.
(b) Turn ignition switch ON and push TOYOTA hand −held tester main switch ON.
CHECK:
Read STA signal on the TOYOTA hand −held tester while starter operates.
OK:
Ignition Switch PositionONSTART
STA SignalOFFON
OK Proceed to next circuit inspection shown on matrix chart (See page DI−19 ).
NG
2 Check for open in harness and connector between ECM and starter relay (See page IN−28 ).
NG Repair or replace harness or connector.
OK
Check and replace ECM
(See page IN−28 ).
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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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S00816
BatteryFusible
Link
F8F7
11
W−R
3EA2
W−R11 6
IG Switch B−R
Fuse BlockIGN B−L
22
22 2
2
EFI Main Relay
1
2
3 4
EFI R
−Y
EC
EB
B−R
1EB1
R
Y−R
Y−REA2IH1
22 7
BR−B E4
E7 E7 E7
IGSW
MRLY
+B
E1 B+
ECM
1
3
12
24FL AM2
FL MAIN
W R
R/B No.2 Y
DI−11 0
−
DIAGNOSTICS ENGINE
1996 LAND CRUISER (RM451U)
ECM Power Source Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned ON, battery positive voltage is applied t\
o the coil, closing the contacts of
the EFI main relay (Marking: EFI) and supplying power to the terminals +B\
of the ECM.
WIRING DIAGRAM
DI5PX−02
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Version 1.11 - 03/16/2010

A00191
ONMRLY(+)
(−)
BE6653
P24682
−
DIAGNOSTICS ENGINE
DI−11 3
1996 LAND CRUISER (RM451U)
6 Check voltage between terminal MREL of ECM connector and body ground.
PREPARATION:
(a) Remove instrument panel speaker No.1 panel
(See page SF−65 ).
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminal MREL of ECM and body
ground.
OK:
Voltage: 9 − 14 V
NG Check and replace ECM.
OK
7 Check EFI fuse (Marking: EFI) (See page DI−105).
NG Check for short in all the harness and
components connected to EFI fuse.
OK
8 Check EFI main relay (Marking: EFI) (See page SF−54).
NG Replace EFI main relay (Marking: EFI).
OK
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P22480
BatteryStarter
FL MAIN
FL AM2EFI
EFI Main Relay
IG Switch IG
ST
Park/Neutral
Position SwitchCircuit Opening
Relay
Fuel Pump Relay
Fuel Pump
From Crankshaft Position
Sensor Fuel Pump
Resistor
(STA Signal)
(NE Signal) MRLY
FC
STA
NE
Tr1
Tr2
ECM
IGN FPR
−
DIAGNOSTICS ENGINE
DI−11 5
1996 LAND CRUISER (RM451U)
Fuel Pump Control Circuit
CIRCUIT DESCRIPTION
In the diagram below, when the engine is cranked, current flows form terminal ST of the igni\
tion switch to
terminal STA of ECM (STA signal).
When the STA signal and NE signal are input to the ECM, Tr1 is turned ON, current flows to coil of the circuit
opening relay, the relay switches on, power is supplied to the fuel pump and the fuel\
pump operates.
While the NE signal is generated (engine running), the ECM keeps Tr1 ON (circuit opening relay ON) and
the fuel pump also keeps operating.
The fuel pump speed is controlled at 2 levels (high speed or low speed) b\
y the condition of the engine (start-
ing, light load, heavy load). When the engine starts (STA ON), Tr2 in the ECM is OFF, so battery voltage is
applied directry to the fuel pump. Fuel pump operates at high speed.
After the engine starts, during idling or light loads, since Tr2 goes ON, power is supplied to the fuel pump
via the fuel pump resistor.
Fuel pump operates at low speed.
DI5PY−02
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Version 1.11 - 03/16/2010