Programmable Communication Interface Bus System

The PCI bus is a single wire multiplexed network capable of supporting binary encoded messages shared between modules. Each module uses its local ground as bus reference. If more than one module is trying to access the PCI bus at one time, the code being sent determines which message has higher priority, and is then allowed to access bus first. Communication over the bus is essential to proper operation of vehicle's on-board diagnostic systems and Diagnostic Readout Box (DRBIII(R)). Problems with operation of bus or DRBIII(R) must be corrected before proceeding with diagnostic testing.