GENERAL INFORMATION
The common rail fuel Injection system
consists of sensors which detect the condition of the diesel engine, an
engine electronic control unit (engine-ECU) which controls the system
based on signals from these sensors, and actuators which operate
according to control commands from the engine-ECU. The engine-ECU
carries out activities such as fuel injection control and idle speed
control. In addition, the engine-ECU is equipped with several
self-diagnosis functions which make troubleshooting easier in the event
that a problem develops.
FUEL INJECTION CONTROL
The injector drive time, the
injection timing and the fuel pressure are controlled so that the
appropriate quantities of fuel are supplied to the engine in response to
engine conditions which can change frequently. A single injector is
mounted at each cylinder. The supply pump increases the fuel pressure to
the pressure which is required for high-pressure injection, and then
send the fuel each injector.
IDLE SPEED CONTROL
The idle speed is kept at the optimum
speed by controlling the fuel injection quantity in accordance with
changes in idling conditions and engine load during idling.
The
engine-ECU drives the fuel injector to keep the engine running at the
pre-set idle target speed in accordance with the engine coolant
temperature and A/C and other electrical load.
SELF-DIAGNOSIS FUNCTION
- When an abnormality is detected in any of the sensors or
actuators, the engine warning lamp illuminates to warn the
driver.
- When an abnormality is detected in any of the sensors or
actuators, a diagnosis code number corresponding to the problem
which occurred is set.
- The RAM data relating to the sensors and actuators which is
stored in the engine-ECU can be read using the M.U.T.-III. In
addition, the actuator can be force-driven under certain
conditions.
OTHER CONTROL FUNCTIONS
- Power Supply Control
When the ignition switch ON signal is
input by the ignition switch, the engine-ECU turns ON the power
transistor for controlling the engine control relay. As a
result, current flows through the coil in the engine control
relay, causing the relay switch to turn ON and supply power to
the sensors and actuators.
- Glow Control
Refer to GROUP 16
(Refer to 
, GROUP 16
- Glow System).
- Exhaust Gas Recirculation Control
Refer to GROUP
17
[Refer to , GROUP 17
- Engine And Emission Control - Exhaust Gas
Recirculation System].
- A/C Relay Control
Turns the compressor clutch of the A/C ON
and OFF.
- A/C Condenser Fan Motor Relay Control
Controls the condenser
fan motor relay based on the A/C switch , A/C load signal,
engine coolant temperature and vehicle speed input
signals.
- PTC Heater Relay Control
The PTC heater is turned ON in
accordance with the A/C operation at the engine cold
state.
FUEL INJECTION SYSTEM
DIAGRAM
