Toyota COMPUTER-CONTROLLED SYSTEM Training Manual page 70

EFI - Fuel Syste m
7 . INJECTOR DRIVE METHOD S
There are two injector drive methods . One is the
voltage control method, and the other is the
current control method .
High-resistance
injectors
(Most engines )
Voltage
contro l
Injector
drive
method
Low-resistance
injectors
(Some engines)
VOLTAGE CONTROL METHOD FOR LOW-
RESISTANCE INJECTORS
The electrical circuitry for this type of injector,
as well as its operation, are basically the same
as for the high-resistance injector, but since a
low-resistance injector is used, a solenoid
resistor is connected between the ignition
switch and the injectors .
The electrical circuitry for simultaneous injection
(See page 66) is shown below .
Ignition switc h
Current
control
Low-resistance injectors
(No longer in use )
VOLTAGE CONTROL METHOD FOR HIGH-
RESISTANCE INJECTOR S
Battery voltage is applied to the injectors
directly via the ignition switch .
When the transistor (Tr) in the Engine ECU goes
on, current flows from terminals No . 10 and No .
20 to E01 and E02 . While the Tr is on, current
flows through the injectors and fuel is injected .
The electrical circuitry for simultaneous injection
(See page 66) is shown below.
Ignition switch
OHP 49
OHP 49
60