Information Bus: Description and Operation

Multiplex Communication Network System
There are several electronic components which can be controlled by an off-board tester to provide valuable self-diagnostic information. These components are part of an electrical system network, designed to control powertrain and body subsystems. The overall electronic network system consists of a Powertrain Control Module (PCM) communication link and two micro-processor based modules which interface through a common communication link. The common link is routed throughout the vehicle in a "bus" configuration or party line. Modules connect to this bus so that the bus serves as a common point to every module. The PCM uses a separate communication link. This link consists of a pair of wires that have been twisted to eliminate any external "noise" from affecting communication between the off-board tester and the PCM.

Module Identification






Modules on this multiplex communication network include:

Anti-Lock Brake Module (ABS)
The anti-lock brake control module is located under the right front seat. The anti-lock brake control module supplies information for:
^ Anti-lock brakes.
^ Wheel speed signal.
^ On-board diagnostics.

Remote Anti-Theft Personality (RAP)
The Remote Anti-Theft Personality (RAP) module is located in the luggage compartment, behind the right rear quarter trim panel for sedans and behind the left rear quarter trim panel for wagons. Vehicle features that are affected by the RAP module include:
^ Remote keyless entry.
^ Anti-theft.
^ On-board diagnostics.

Powertrain Control Module (PCM)
The Powertrain Control Module (PCM) is located in the center console. Vehicle features that are affected by the PCM include:
^ Engine performance.
^ Electronic Ignition (EI) system.
^ Emissions control.