13
ELECTRONIC CONTROL SYSTEM
- Fuel Control Switch or Connector,
EGR Gas Temperature Senso
r
FUEL CONTROL SWITCH OR
CONNECTOR
EGR GAS TEMPERATURE
SENSO
R
This switch or connector informs the Engine ECU
whether the gasoline being used is regular or
premium
.
This signal is used mainly in controlling the ESA
system
. The Engine ECU has two sets of
advance angle data for different types of
gasoline (regular or premium)
. If the Engine ECU
judges that regular gasoline is being used, it
uses the data for the smaller angle of advance
.
If it judges that premium gasoline is being used,
it uses the data for the larger angle of advance
.
ELECTRICAL CIRCUITRY
Engine ECU
This sensor is mounted in the EGR valve
. It
detects the temperature of the EGR gas
. This
sensor is composed of a thermistor, and it
resembles the water temperature sensor or
intake air temperature sensor
. The signals from
this sensor are used in the diagnostic system
.
When this sensor detects EGR gas temperatures
below a predetermined level during EGR system
operation, the Engine ECU judges that the EGR
system is malfunctioning and lights the "CHECK
ENGINE" lamp to inform the driver
.
ELECTRICAL CIRCUITRY
Engine EC
U
OHP 3
5
I
NOT
E
Fuel Control Connecto
r
In some vehicle models, this connector should
be connected when permium gasoline is used,
and disconnected
when regular gasoline is us-
ed
. In other models, the situation is the op-
posite
.
Refer to the owner's manual for the location of
the connector and the changeover procedure
between regular gasoline and premiu
m
gasoline
.
Fuel control connector
OHP 3
5
REFERENCE
Some recent D-EFI systems do not use an EGR
gas temperature sensor
. In these systems, EGR
operation is checked by detecting fluctuations
in the intake manifold pressure with a manifold
pressure sensor (vacuum sensor)
.
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