Principles of Operation

PRINCIPLES OF OPERATION

The vehicle has 3 module communication networks: high speed and medium speed CAN network, which are comprised of unshielded twisted pair cable, and the international standards organization (ISO) 9141 communication network, which is a single wire network. All 3 networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing a diagnostic tester to be able to diagnose and control any module on the 3 networks from the connector. The DLC can be found under the instrument panel between the steering column and the radio.

The high speed and medium speed CAN remain operational even with the severing of one of the bus wires. Communications will also continue if one of the bus wires is shorted to ground or voltage. If any of the termination resistors are lost, communication is not possible.

The ISO 9141 communication network does not permit intermodule communication. When the diagnostic tool communicates to modules on the ISO 9141 communication network, the diagnostic tool must ask for all information; the modules cannot initiate communications.

The ISO 9141 communication network will not function if the wire is shorted to ground or battery voltage. Also, if one of the modules on the ISO 9141 communication network loses power or shorts internally, communication to that module will fail.