Principles of Operation: Notes

WARNING: This page is about a different car, the 2005 Ford RV Cutaway, 2005 Ford Econoline, 2005 Ford E450 Super Duty, and 2005 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

The vehicle has 2 module communications network protocols:

International Standards Organization (ISO) 9141 communications network
controller area network (CAN)

The ISO 9141 communications network is a single wire communications network circuit 70 (LB/WH). The CAN is an unshielded, twisted pair cable communications network, circuit 1827 (WH/LG) and circuit 1828 (PK/LG). Both communications networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one diagnostic tool to be able to diagnose and control any module on the communications networks from one connector. The DLC can be found under the instrument panel and the steering column.

The ISO 9141 communications network does not permit intermodule communication. When the diagnostic tool communicates to modules on the ISO 9141 communications network, the diagnostic tool must ask for all information; the modules cannot initiate communications. The ISO 9141 communications network does not function if the circuit is shorted to ground or battery voltage. Also, if one of the modules on the ISO 9141 communications network loses power or shorts internally, communications to that module fail.