Toyota COMPUTER-CONTROLLED SYSTEM User Manual

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~ ►
REFERENCE
Circuit-opening Relay
EFI - Fuel Syste m
The resistor R and the capacitor C in the
circuit-opening relay are for the purpose of
preventing the relay contacts from opening
when current stops flowing in coil L2 due to
electrical noise ( fuel pumps controlled by the
ECU) or to sudden drops in the intake ai
r
ON-OFF CONTROL (BY FUEL PUMP SWITCH)
*
~) Engine crankin g
When the engine is cranking, current flows from
the IG terminal of the ignition switch to the Li
coil of the EFI main relay, turning the relay on .
Current also flows from the ST terminal of the
ignition switch to the La coil of the circuit-
opening relay, turning it on to operate the fuel
pump
. After the engine starts, the cylinders
begin drawing in air, causing the measuring
plate inside the air flow meter to open . This
turns on the fuel pump switch, which is
connected to the measuring plate, and current
flows to the Lz coil of the circuit-opening relay .
~2 Engine sta
rt
e
d
After the engine sta
rt s and the ignition switch is
turned from START back to ON, current flowing
volume ( fuel pumps controlled by fuel pump
switch) .
They also serve to prevent sparks from being
generated at the relay contacts
.
On some recent models, an L3 coil is not
provided in the circuit-opening relay .
to the La coil of the circuit-opening relay is cut
off . However, current continues to flow to the Ls
coil, while the engine is running, due to the fuel
pump switch inside the air flow meter being on .
As a result, the circuit-opening relay stays on,
allowing the fuel pump to continue operating .
~3 Engine stoppe d
When the engine stops, the measuring plate
completely closes and the fuel pump switch is
turned off
. This cuts off the flow of current to
the Ls coil of the circuit-opening relay
. As a
result, the circuit-opening relay goes off and the
fuel pump stops operating .
L-type EFI with vane type air flow meter
.
Check (m p T~
Circuit-opening rela y
connecto r
Battery
2P fuel pump check connector (some
engines only )
-
IN
OHP 4 6
56

Toyota COMPUTER-CONTROLLED SYSTEM Specifications

General

Brand	Toyota
Model	COMPUTER-CONTROLLED SYSTEM
Category	Automobile Accessories
Language	English