Principles of Operation

PRINCIPLES OF OPERATION

The vehicle has 4 module communications networks:
- the standard corporate protocol (SCP) communications network.
- the international standards organization (ISO) 9141 communications network.
- the universal asynchronous receiver-transmitter (UART)-based protocol (UBP) communications network.
- the controller area network (CAN).

The diagnostic tool connects to all 4 communications networks through 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 4 communications networks from one connector. The DLC is found under the instrument panel between the steering column and the radio.

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 request all information; or initiate module commands. 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.

The SCP communications network remains operational even with the severing of one of the SCP communications network circuits. Communications also continue if one of the communications network circuits are shorted to ground or voltage, or if some but not all termination resistors are lost.

The UBP communications network does not function if the circuit is shorted to ground or voltage. The UBP communications network is different from the ISO 9141 communications network in that it allows intermodule communication.

The CAN has an unshielded twisted pair cable, data plus circuit 1827 (WH/LG) and data minus circuit 1828 (PK/LG). The CAN is a communications network used for the anti-lock brake system (ABS) module and the powertrain control module (PCM) communication. The CAN remains operational even with the severing of one of the CAN circuits. Communications also continue if one of the CAN circuits are shorted to ground or voltage, or if some, but not all, termination resistors are lost.

ABS Module
The ABS module uses the CAN. The ABS module controls the brake pressure to the 4 wheels to keep the vehicle under control while braking.

Audio Control Module (ACM)
The ACM uses the SCP communications network and also to the audio control protocol (ACP) communications protocol. The ACM communicates with the compact disc player/changer and the rear seat controls module using the ACP communications protocol. If equipped, the rear seat audio/climate controls are located in the rear seat armrest. The ACM uses the SCP communications network for diagnostics.

ACM (with Navigation Display & built-in 6 CDDJ)
The ACM uses the CAN and the ACP communications protocols. The ACM communicates with the rear seat controls module using the ACP communications protocols. If equipped, the rear seat audio/climate controls are located in the rear seat armrest. The ACM uses the CAN to communicate with the navigation system module. The ACM (with navigation display) can not be accessed directly by the scan tool.

Driver Door Module (DDM)
The DDM uses the SCP communications network. The module controls many functions including power windows, power locks, and remote keyless entry (RKE). The DDM also communicates with the DSM to control power seat and mirror memory.

Driver Seat Module (DSM)
The DSM uses the SCP communications network. The DSM controls the positioning and programming of the driver seat, pedals and both outside mirrors.

Dual Automatic Temperature Control (DATC)
Module The DATC module uses the SCP communications network. The DATC module controls automatic climate functions that maintain the vehicle at a constant temperature setting.

Message Center Module
The message center module uses the SCP communications network. The message center module computes and displays oil life, and compass heading.

Instrument Cluster
The instrument cluster uses the SCP communications network. The instrument cluster has an analog face cluster with a digital odometer. The instrument cluster displays a variety of information.

Lighting Control Module (LCM)
The LCM uses the SCP communications network. The LCM controls both interior and exterior lighting and warning chimes.

Luggage Compartment Lid Module
The luggage compartment lid module uses the ISO 9141 communications network. The module controls the motor that opens and closes the luggage compartment lid.

Navigation System Module
The navigation system module uses the SCP communications network. The navigation system module uses the SCP communications network for diagnostic communications, and the CAN to communicate with the ACM/navigation display unit. The vehicle navigation system provides a feature that guides the user to any entered destination. The system uses the global positioning sensor (GPS), vehicle speed, and other sensor information to accurately establish the vehicle position. The navigation system module compares this position to the CD-ROM vector map. The system then provides the maneuvers required during the journey in order to arrive at the destination entered.

Parking Aid Module
The parking aid module uses the UBP communications network. The module controls sensors in the rear bumper that detect close objects when the vehicle is in REVERSE.

Powertrain Control Module (PCM)
The PCM uses the CAN and the SCP communications networks. The PCM controls the engine for better fuel economy, emissions control and failure mode detection storage.

Rear Air Suspension Module
The rear air suspension module uses the SCP communications network. The rear air suspension module controls the rear ride height.

Restraint Control Module (RCM)
The RCM uses the ISO 9141 communications network. The RCM controls the deployment of the air bags based on sensor input.