Communications Network: Notes

WARNING: This page is about a different car, the 2009 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The smart junction box (SJB) is also known as the generic electronic module (GEM).

Vehicle communication utilizes the International Standards Organization (ISO) 9141 network, the medium speed controller area network (MS-CAN), and the high speed controller area network (HS-CAN). Information is sent to and from individual control modules that each control specific functions. All 3 networks are connected to the data link connector (DLC). The DLC can be found under the instrument panel between the steering column and the audio control module (ACM).

The 3 module communication networks are:

ISO 9141
Medium speed (MS) CAN
High speed (HS) CAN

All 3 networks are connected to the 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 ACM.

Fig 1: Network Topology

Courtesy of FORD MOTOR CO.

Module Name	Network Type	Termination Module
ABS module (if equipped)	HS-CAN	No
Audio control module (ACM)	MS-CAN	No
Instrument cluster (IC) (gateway module)	HS-CAN MS-CAN	Yes Yes
PCM	HS-CAN	Yes
Restraints control module (RCM)	ISO 9141	N/A
Satellite digital audio receiver system (SDARS) module (if equipped)	MS-CAN	No
Smart junction box (SJB)	MS-CAN	Yes