Introduction

SYSTEM DESCRIPTION AND FUNCTIONAL OPERATION
The body system on the 1998 Ram Truck consists of three modules that communicate over the CCD bus (Chrysler Collision Detection multiplex system). There are three additional modules, two types of Powertrain Control Modules (PCM) and the Controller Anti-Lock Brake (CAB) that are not part of the body system, but do utilize the CCD bus for communication. The CAB also utilizes the bus for diagnostics. The PCM sends and receives messages on the CCD bus, however diagnostics are performed through the Serial Communication Interface or SCI, the same as last year. All of the information about the functioning of all the systems is organized, controlled, and communicated by the CCD bus, which is described in this general information section.

Through the CCD bus, information about the operation of vehicle components and circuits is relayed quickly to the appropriate module(s). All modules receive all the information transmitted on the bus even though a module may not require all the information to perform it's function. It will only respond to messages addressed to it through a binary coding process. This method of data transmission significantly reduces the complexity of the wiring in the vehicle and the size of wiring harnesses.