Kohler Command PRO ECV630, Руководство по обслуживанию

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5.4
Section 5
EFI Fuel System
Figure 5-1. Electronic Control Unit (ECU).
General
The ECU is the brain or central processing computer
of the entire EFI system. During operation, sensors
continuously gather data which is relayed through
the wiring harness to input circuits within the
ECU. Signals to the ECU include: ignition (on/
o
ff ), cranksha ft position and speed (RPM), thro tt le
position, oil temperature, intake air temperature,
exhaust oxygen levels, manifold absolute pressure,
and ba
tt ery voltage.
The ECU compares the input signals to the
programmed maps in its memory to determine the
appropriate fuel and spark requirements for the
immediate operating conditions. The ECU then sends
output signals to set the injector duration and ignition
timing.
The ECU continually performs a diagnostic check
of itself, each of the sensors, and the system
performance. If a fault is detected, the ECU can turn
on a Malfunction Indicator Light (MIL) (if equipped)
on the equipment control panel, store the fault code
in its fault memory, and go into a default operating
mode. Depending on the signi
fi cance or severity of the
fault, normal operation may continue. A technician
can access the stored fault code using a blink code
diagnosis
fl ashed out through the MIL. An optional
computer so ft ware diagnostic program is also
available, see Section 2.
The ECU requires a minimum of 6.0 volts to operate.
To prevent engine over-speed and possible failure, a
rev-limiting feature is programmed into the ECU. If
the maximum RPM limit (4500) is exceeded, the ECU
suppresses the injection signals, cu
tt ing o ff the fuel
fl ow. This process repeats itself in rapid succession,
limiting operation to the preset maximum.
Service
Never a tt empt to disassemble the ECU. It is sealed to
prevent damage to internal components. Warranty
is void if the case is opened or tampered with in any
way.
All operating and control functions within the ECU
are preset. No internal servicing or readjustment may
be performed. If a problem is encountered, and you
determine the ECU to be faulty, contact your source
of supply. Do not replace the ECU without factory
authorization.
The ECU pins are coated at the factory with a thin
layer of electrical grease to prevent fre
tt ing and
corrosion. Do not a tt empt to remove the grease from
the ECU pins.
• Avoid direct water or spray contact with system
components.
• Do not disconnect or reconnect the ECU wiring
harness connector or any individual components
with the ignition on. This can send a damaging
voltage spike through the ECU.
• Do not allow the ba tt ery cables to touch opposing
terminals. When connecting ba tt ery cables a tt ach
the positive (+) cable to the positive (+) ba tt ery
terminal fi rst, followed by the negative (-) cable to
the negative (-) ba tt ery terminal.
• Never start the engine when the cables are loose
or poorly connected to the ba tt ery terminals.
• Never disconnect the ba tt ery while the engine is
running.
• Never use a quick ba tt ery charger to start the
engine.
• Do not charge the ba tt ery with the key switch
ON.
• Always disconnect the negative (-) ba tt ery cable
before charging the ba tt ery, and also unplug the
harness from the ECU before performing any
welding on the equipment.
Electrical Components
Electronic Control Unit (ECU)