EMS 2 - “Engine Management System”
Group 30: Electrical system
8
EMS 2 - “Engine Management System”
General information
EMS 2 is an electronic system with CAN communication (Controller Area Network) for diesel engine control. The
system has been developed by Volvo and includes fuel control and diagnostic function.
The system consists of a control module, six injectors, a number of sensors that supply the control module with
measurements, sockets for diagnosis and functional checks. The engine can be connected to a communications
interface consisting of a CAN link and a serial link.
CAN - Controller Area Network
The J1939 CAN link is responsible after all communi-
cation between the engine control unit (EMS 2) and a
communication interface (such as CIU/DCU), except
for diagnostics. Diagnostics are managed by the so-
called J1708/J1587 link. The CAN link is much faster
than the J1708/J1587 link and has been designed to
connect to other components that support the SAE
J1939 protocol, such as instrument panels and trans-
missions.
If a fault develops on the CAN link, signals for the en-
gine speed potentiometer, and the start and stop
knobs are taken over by the J1708/J1587 link. Howev-
er, instrument and indicator lamps are completely
turned off.
If faults occur in both links, the engine starts to idle.
The only way to shut off the engine in this case is to
use the auxiliary stop (AUX-STOP).