Description & Operation

NOTE: Anti-theft/double locking module may also be referred to as Central Security Module (CSM). Hybrid Electronic Cluster (HEC) module is built into instrument cluster. Air bag control module may also be referred to as electronic crash sensor module.

Vehicle has 2 module communications networks. The Powertrain Control Module (PCM) is connected to the multiplex communications network through a pair of twisted wires or bus. If vehicle is equipped with traction control, the Anti-Lock Brake System (ABS) module is also connected to bus. The bus network is also referred to as Standard Corporate Protocol (SCP). The bus consists of (+) circuit and a (-) circuit.

The ABS module is also connected to the ISO 9141 diagnostic communications network through a single wire along with the air bag control module, anti-theft/double locking module (if equipped) and Hybrid Electronic Cluster (HEC) module. Both networks are connected to the Data Link Connector (DLC). This article is used to diagnose bus and ISO communications network circuit faults. For module locations, see COMPONENT LOCATIONS .