Description & Operation

Vehicle has 2 module communications networks. The Standard Corporate Protocol (SCP) network communicates over a pair of unshielded twisted wires (data bus). The SCP bus links the Powertrain Control Module (PCM), Passive Anti-Theft System (PATS) module, Electronic Automatic Temperature Control (EATC) module and Data Link Connector (DLC). The International Standards Organization (ISO) 9141 network communicates over a single wire connecting the Restraints Control Module (RCM), Generic Electronic Module/Central Timer Module (GEM/CTM), 4-Wheel Anti-Lock Brake System (4WABS) module, Driver Seat Module (DSM), Parking Aid Module (PAM), Air Suspension Control (ARC) module and DLC.

SCP network has the ability to continue to function with one of its wires open, shorted to power or shorted to ground. ISO 9141 network is unable to function if an open or short occurs in its wire. ISO 9141 network does not allow intermodule communication. Scan tool must initiate communication with modules on ISO 9141 network. Both networks can be accessed with scan tool at DLC. This article is used to diagnose SCP and ISO 9141 communications network circuit faults. For module locations, see COMPONENT LOCATIONS .