1996 TOYOTA LAND CRUISER Fuel pump power

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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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Version 1.11 - 03/16/2010

DI5OY−03
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DIAGNOSTICS ENGINE
DI−19
1996 LAND CRUISER (RM451U)
PROBLEM SYMPTOMS TABLE
When the malfunction code is not confirmed in the DTC check and the problem \
still can not be confirmed
in the basic inspection, then proceed to this step and perform troubleshooting according to the numbered
order given in the table below.
SymptomSuspect AreaSee page
Engine does not crank (Does not start)1. Starting systemST−16
No initial combustion (Does not start)1. ECM power source circuit
2. Fuel pump control circuitDI−11 0
DI−11 5
No complete combustion (Does not start)1. Fuel pump control circuitDI−11 5
Engine cranks normally (Difficult to start)
1. Starter signal circuit
2. Fuel pump control circuit
3. CompressionDI−103
DI−11 5 EM−3
Cold engine (Difficult to start)1. Starter signal circuit
2. Fuel pump control circuitDI−103DI−11 5
Hot engine (Difficult to start)
1. Starter signal circuit
2. Fuel pressure control circuit
3. Fuel pump control circuitDI−103
DI−125DI−11 5
High engine idle speed (Poor idling)1. A/C signal circuit
2. ECM power source circuitAC−5
DI−11 0
Low engine idle speed (Poor idling)1. A/C signal circuit
2. Fuel pump control circuitAC−5
DI−11 5
Rough idling (Poor idling)1. Compression
2. Fuel pump control circuitEM−3
DI−11 5
Hunting (Poor idling)1. ECM power source circuit
2. Fuel pump control circuitDI−11 0
DI−11 5
Hesitation/Poor acceleration (Poor driveability)1. Fuel pump control circuit
2. A/T faultyDI−11 5
DI−147
Surging (Poor driveability)1. Fuel pump control circuitDI−11 5
Soon after starting (Engine stall)1. Fuel pump control circuitDI−11 5
During A/C operation (Engine stall)1. A/C signal circuit
2. Engine control module (ECM)AC−5
IN−18
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Version 1.11 - 03/16/2010

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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Brought to you by BirfMark
Version 1.11 - 03/16/2010