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3-38 FUEL SYSTEM (DFI)
Self-Diagnosis
Backu ps
○
The ECU takes the following measures to prevent engine dam age when the DFI or the ignition
system parts have troubles.
Service
Codes
Parts
Output Signal Usable
Range or Criteria
Backups by ECU
11
Main
Throttle
Sensor
Main Throttle Sensor
Output Voltage
0.2 ∼ 4.8 V
If the main throttle sensor system fails (the signal
is out of the usable range, wiring short or open),
the ECU locks ignition timing into the ignition
timing at closed throttle position and sets the DFI
in the D-J method.
Also, the main throttle sensor system and inlet air
pressure fails, the ECU locks ignition timing into
the ignition timing at closed throttle position and
sets the DFI in the α-N method.
12
Inlet Air
Pressure
Sensor
Inlet Air Pressure
(absolute)
Pv = 100 mmHg ∼ 900
mmHg
If the inlet air pressure sensor system fails (the
signal Pv is out of the usable range, wiring short
or open), the ECU sets the DFI in the α -N
method.
13
Inlet Air
Tempera-
ture Sensor
Inlet Air Temperature
Ta = – 47°C ∼ + 178°C
If t
he inlet air temperature sensor fails (the signal
is out of the usable range, wiring short or open),
the ECU sets Ta at 40°C.
14
Water Tem-
perature
Sensor
Water Tem perature
Tw = – 30C° ∼ + 120°C
If the water temperature sensor system fails (the
signal is out of the usable range, wiring short or
open), the ECU sets Tw at 80°C.
15
Atmo-
spheric
Pressure
Sensor
Absolute Atmospheric
Pressure
Pa = 100 mmHg ∼ 900
mmHg
If the atmospheric pressure sensor system fails
(the signal is out of the usable r ange, wiring short
or open), the ECU sets Pa at 760 mmHg (the
standard atmospheric pressure).
21
Crankshaft
Sensor
Crankshaft sensor must
send 23 signals (output
signal) to the ECU at the
one cranking.
If crankshaft sensor generates other than 23
signals, the engine stops by itself.
23
Camshaft
Position
Sensor
Cam sensor must send
one signal (output signal)
to the ECU at the two
cranking
If the camshaft position sensor system fails
(the signal is m issing, wiring short or open), the
ECU continues to ignite cylinders in the sam e
sequence following the last good signal.
24
and
25
Speed
Sensor
Speed sensor must send
4 signals (output signal)
to the ECU at the one
rotation of the engine
sprocket.
The gear position is
decided by the signal of
the speed sensor.
If the speed sensor system fails (no signal, wiring
short or open), the speedometer shows 0, and
the ECU sets the top (6) gear position.
31
Vehicle
-down
Sensor
Vehicle-down Sensor
Output Voltage (signal)
Vd = 0.4 V ∼ 4.4 V
If the vehicle-down sensor system has failures
(the output voltage Vd is more than usable range,
wiring open), the ECU shuts off the fuel pump,
the fuel injectors and the ignition system.
32
Subthrottle
sensor
Subthrottle Sensor
Output Voltage
0.15 ∼ 4.85 V
If the subthrottle sensor system fails (the signal
is out of the usable range, wiring short or open),
the actuator locks sub throttle valve at full open
position.