Description & Operation

Vehicle has 2 module communications networks. The module communications network provides the ability for module-to-module communication by sharing inputs and outputs instead of each component having an input and output wired directly to each module. A BUS which consists of a pair of twisted wires is used to transfer information between each module. The BUS network is also referred to as Standard Corporate Protocol (SCP) network. The BUS consists of a (+) circuit No. 914 and a (-) circuit No. 915. The BUS is routed throughout the vehicle to Powertrain Control Module (PCM), Electronic Automatic Temperature Control (EATC) module, Anti-Lock Brake System (ABS) module, Passive Anti-Theft System (PATS) module and Natural Gas Vehicle (NGV) module (if equipped). The Lighting Control Module (LCM), Driver's Door Module (DDM), Electronic Crash Sensor (ECS) module do not use the BUS to communicate with other modules. The LCM, DDM and ECS module are connected to the International Standards Organization (ISO) 9141 diagnostic communications network through a single wire (circuit No. 70). Both networks are connected to the Data Link Connector (DLC). This article is used to diagnose BUS and ISO communications network circuit faults.