Description & Operation

Vehicle has 2 module communication 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 (Tan/Orange wire) and a (-) circuit No. 915 (Pink/Light Blue wire). 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 Module (NGVM), if equipped. The Restraint Control Module (RCM), Driver's Door Module (DDM) and Lighting Control Module (LCM) do not use the SCP bus to communicate with other modules. The ABS, DDM, LCM and RCM modules are connected to the International Standards Organization (ISO) 9141 diagnostic communication network through a single Light Blue/White wire (circuit No. 70). Both networks are connected to the Data Link Connector (DLC). This article is used to diagnose SCP bus and ISO communication network circuit faults.

Some vehicles are equipped with Electric Variable Assist (EVO) power steering. If vehicle is equipped with EVO, steering is controlled by EVO steering module. If vehicle is equipped with EVO and rear air suspension, air suspension/EVO steering module controls rear suspension and power steering. Air suspension/EVO steering module and EVO steering module do not use network communications.