1996 TOYOTA LAND CRUISER Starter relay

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INTRODUCTION HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN−25
1996 LAND CRUISER (RM451U)
5. PROBLEM SYMPTOMS TABLE
The suspected circuits or parts for each problem symptom are shown in th\
e table below. Use this table to
troubleshoot the problem when a ”Normal” code is displayed in the \
diagnostic trouble code check but the
problem is still occurring. Numbers in the table indicate the inspection order in which the circuits or parts
should be checked.
HINT:
When the problem is not detected by the diagnostic system even though the pr\
oblem symptom is present,
it is considered that the problem is occurring outside the detection ran\
ge of the diagnostic system, or that
the problem is occurring in a system other than the diagnostic system.
Symptom
Suspected AreaSee page
Engine does not crank (Does not start)
No initial combustion (Does not start)
No complete combustion (Does not start) 1. Starter and starter relay
1. ECM power source circuit
2. Fuel pump control circuit
3. ECM
1. Starter signal circuit
2. Fuel pump control circuit 1. Fuel pump control circuit
DI−147
DI−151
IN−29
PROBLEM SYMPTOMS TABLE
1. Compression
2. Fuel pump control circuit 1. A/C signal circuit
2. Fuel pump control circuit 1. A/C signal circuit (Compressor circuit)
2. ECM power source circuit 1. Starter signal circuit
2. Fuel pump control circuit1. Starter signal circuit
2. Fuel pump control circuit
3. Compression
idling)
High engine idle speed (Poor idling) Hot engine
Cold engine (Difficult to start) Engine cranks normally (Difficult to start)
AC−88 DI−144
DI−151
EM−3 DI−151
 Problem Symptom Page
Indicates the page where the flow chart for each circuit
is located.
 Circuit Inspection, Inspection Order
Indicates the circuit which needs to be checked for each problem
symptom. Check in the order indicated by the numbers.
 Circuit or Part Name
Indicates the circuit or part which needs to be checked.
ST−2
ST−17
DI−144
DI−151
DI−144
DI−151
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DI−104
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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
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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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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
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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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