16
Group 23 EDC III
Design and operation
Electronic Control Unit (ECU) (11)
The control module (EMS) checks and controls the
unit injectors so that the correct amount of fuel is in-
jected into each cylinder. It calculates and sets the in-
jection angle. This control is done primarily with the
help of the tachometer sensors and the combined
sensor for charge air pressure/temperature.
The EDC III system processor is located in the con-
trol unit, protected from moisture and vibrations.
The processor continually receives information regar-
ding:
•
engine speed
•
charge air pressure
•
charge air temperature
•
coolant temperature
•
oil pressure
•
oil temperature
•
fuel alarm, combined alarm for ”water in fuel” and
”fuel pressure”
•
coolant level
This information is used to make exact determinations
on current operating conditions and allows the proces-
sor to calculate the correct amount of fuel, check the
condition of the engine, etc.
Coolant level monitor (1)
This monitor is located in the expansion tank.
Its task is to detect if the coolant level in the cooling
system (expansion tank) is too low. The monitor con-
sists of a contact that can be actuated magnetically.
A hull located around the monitor actuates the contact
differently depending on the coolant level. An alarm
signal is sent if the coolant level is too low.
Control Interface Unit (CIU)
The CIU is a control unit that handles all interaction
with the operator.
It communicates with the engine over two serial com-
munication buses. J1939 is used for controlling and
monitoring the engine. J1587 is used for diagnostics
and backup.
The CIU loads a number of switches and speed re-
quests and forwards them to the engine. It also con-
trols four analogue instruments and up to nine warning
lamps. Using a diagnosis button and diagnostic lamp,
the operator can read out error codes from the system.
