CCD Bus System

The Chrysler Collision Detection (CCD) bus is a pair of twisted wires traveling from module-to-module to receive and deliver coded information between modules. The code identifies information message and its importance. Codes are sent to all modules, and are addressed to appropriate module for which information is intended. When multiple messages attempt to gain access to CCD bus at once, codes are assigned by address, level of importance and priority ranking. The 2 twisted wires used by CCD bus system are called bus (+) positive and bus (-) (negative). Both wires carry approximately 1.8-2.8 volts. CCD bus network consists of some modules with "bias" and some modules with "termination".

"Bias" is the voltage divider of CTM network, and places both CCD bus (+) and CCD bus (-) circuits at 1.8-2.8 volts. "Termination" is the part of circuitry required to complete the voltage loop in CCD bus circuit and also provides some electromagnetic protection for CCD bus network. Termination in most all CCD bus system applications have a 120-ohm resistor connecting the CCD bus (+) and CCD bus (-) circuits, thus completing the CCD bus circuit. If a fault exists in CCD bus network, it must be corrected before proceeding with any other testing or diagnostics. For CCD bus diagnostic and testing procedures, see SYMPTOM INDEX DIRECTORY  under SYSTEM TESTS.