16 © Scania CV 2009
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 programmed control software, the
correct fuel amount and correct injection time are calculated for each unit
injector 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 checks 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, for
example 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.