
P22480
Battery
Starter
FL MAIN
FL AM2
EFI
EFI Main Relay
IG Switch
IG
ST
Park/Neutral
Position Switch
Circuit 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
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115
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 ignition 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) by 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
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Version 1.00 - 12/21/2010