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© Scania CV 2011
EMS engine management
system
This engine has an electronic management system, EMS (Engine
Management System), with unit injectors (PDE) which provide each cylinder
with the right amount of fuel at the right time in all operating situations.
The EMS system consists of a control unit (S6) and sensors for speed, charge
air temperature and pressure, coolant temperature, oil pressure, accelerator
pedal/throttle actuation which constantly emit signals to the control unit.
With the aid of this input data and the set control program, the correct amount
of fuel and the correct injection time are calculated for each unit injector
(PDE) under the specific operating conditions.
The EMS system sensors can also be used to emit signals to the instruments
in the instrument panel.
The control unit constantly monitors the sensors to make sure they are
operational.
The control unit contains monitoring functions to protect the engine in the
event of a fault which would otherwise damage it. In the event of a fault, e.g.
alarm level for low oil pressure or high coolant temperature, the S6 control
unit sends a CAN message to a coordinator.
The main task of the coordinator is to pass on data by means of CAN
communication from the engine control unit to other control units and signals
to gauges and lamps in the instrument panel. The coordinator also has
monitoring functions.
When the EMS control unit or the coordinator detects a fault, the diagnostics
lamp on the instrument panel(s) comes on, and it stays on as long as the fault
is active. At the same time, a fault code is generated which can be read off via
the coordinator on the diagnostics lamp in the form of a flash code when the
diagnostics switch is activated. A flash code may consist of a number of
different fault codes.
Diagnosis and troubleshooting using Scania EMS display is described in the
Operator's Manual for Scania instrumentation.
If the torque reduction function is activated, the amount of fuel and the engine
power are reduced to 70%, and if engine shutdown is activated, the engine is
switched off at programmed alarm levels.
A separate PC-based diagnostics program is used to read off the contents of
the flash codes. For an in-depth analysis of fault codes, contact an authorised
Scania dealer.
Reading off the fault codes, and descriptions of these, are also covered in a
separate document in the Workshop Manual, Engine Management System
EMS-S6: Troubleshooting.
Only authorised personnel are allowed to carry out diagnostic procedures and
program changes.
The positions of the sensors which emit signals to the control unit are shown
in the illustrations on page 13.
See pages 14 and 16 for a description of how to read off flash codes.
See pages 15 and 17 for a list of flash codes for the control unit and
coordinator.
