This vehicle is equipped with a computer system capable of performing multiple engine and body control functions. Vehicle components (windows, locks, mirrors, etc.) are controlled directly by their system module. Each system communicates with other systems on an ``interconnecting bus'' or serial data line. The following systems are all part of the vehicle's computer system providing two-way communication between various engine and body control systems.

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Communications between each system is accomplished by sending a digitally coded message, consisting of specific information a system module must follow. Some electrical components are directly connected and controlled by their system module. Others systems accomplish this by sharing data information with other systems on the serial data line to execute various vehicle functions. All system data information (sensors, switches, etc.) can be monitored by any system module that completes the vehicle's computer system. All systems on the same serial data line use a communication process similar to a telephone system, where enormous amounts of information can be exchanged on a single data wire. The serial data circuit is used to communicate this information between each system connected to the serial data line. Each system is assigned a specific recognition code (source ID). This code is used to identify which system is communicating on the serial data line. So when a message is sent out on the serial data line, only the particular system module that was assigned that recognition code will responded to the message. These messages contain specific information (or commands) a system requires to function properly. When a system receives a message it also "learns" the source ID of the system that sent it. This source ID is used to determine which system actually sent the message and for State of Health (SOH) monitoring. SOH monitoring determines if a system is unable to communicate properly. By communicating data information with other systems on the same serial data line, either input information or specific program information within the systems memory, can provide more accurate and reliable computer system control functions. Description and diagnosis of each system will be covered in the respective service manual section.