F 250 4WD Super Duty V8-6.4L DSL Turbo (2008)
Information Bus: Description and Operation
COMMUNICATIONS NETWORK
NOTE: The smart junction box (SJB) is also known as the generic electronic module (GEM).
Vehicle communication utilizes both International Standards Organization (ISO) 9141 and controller area network (CAN) communications. ISO 9141 is
for diagnostic use only, and CAN is used for many modules to communicate with each other on a common network. CAN in-vehicle networking, is a
method for transferring data among distributed electronic modules via a serial data bus. Without serial networking, intermodule communication requires
dedicated, point to point wiring resulting in bulky, expensive, complex, and difficult to install wiring harnesses. Applying a serial data network reduces
the number of wires, combining the signals on a single network. Information is sent to the individual control modules that control each function.
The vehicle has 3 module communication networks:
-
ISO 9141
-
Medium speed (MS) CAN
-
High speed (HS) CAN
All 3 networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one scan tool to be
able to diagnose and control any module on the 3 networks from one connector. The DLC can be found under the instrument panel between the steering
column and the audio unit.
