Principles of Operation
The vehicle has three module communication networks: one high speed and one medium speed CAN network, which are comprised of unshielded twisted pair cable, and the international standards organization (ISO) 9141 communications network, which is a single wire network. All three networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one diagnostic tester to be able to diagnose and control any module on the three networks from one connector. The DLC can be found under the instrument panel between the steering column and the radio.
The high speed and medium speed CAN will 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 will not be possible.
The ISO 9141 communications network does not permit intermodule communication. When the WDS or equivalent Tester communicates to modules on the ISO 9141 communication network, the WDS or equivalent Tester must ask for all information; the modules cannot initiate communications.
The ISO 9141 communications network will not function if the wire 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 will fail.
The SJB is located under the front passenger-side floor console. For removal information, See SMART JUNCTION BOX (SJB). For additional information on interior lamps and illuminated entry, See INTERIOR LIGHTING. For additional information on exterior lighting, see EXTERIOR LIGHTING. For additional information on power door locks, keyless entry keypad and RKE, see HANDLES, LOCKS, LATCHES AND ENTRY SYSTEMS. For additional information on the rear windshield wiper, see WIPERS AND WASHERS -- REAR. For additional information on anti-theft, see ANTI-THEFT - PASSIVE ANTI-THEFT SYSTEM (PATS). For additional information on the climate control system, see CLIMATE CONTROL SYSTEM. For additional information on the warning chimes, see GAUGES AND WARNING DEVICES.
Vehicle Identification (VID) Block
Some PCMs contain a memory area called a VID block. The PCM VID block may contain the factory settings for the configurable modules unless the PCM is flashed with a new calibration, in which case some PCM parameters may be modified.
As-Built Data Center
The As-Built Data Center maintains a record of the vehicle configuration in a database. The vehicle identification number (VIN) is required to obtain this information. The As-Built Data Center records the applicable module configurations stored in each module before the vehicle leaves the factory. The As-Built Data Center will always reflect the original build of the vehicle as it left the factory. Only contact the As-Built Data Center when directed to do so by the WDS or equivalent Tester.
See also:
• FOUR-WHEEL DRIVE SYSTEMS