The Chrysler Collision Detection Bus AKA CCD Bus is a two wire vehicle data network that allows communication between the PCM and other modules such as the ABS controller, Door lock modules, Body control module, Tail Lamp module, Instrument cluster, various informational displays, etc. Messages on this bus are wide ranging and varied, from vehicle speed and engine speed, to the messages to instruct your windows to roll down, to the dim level of the interior lighting depending on the vehicle. As far as is known, all devices communicating on the CCD bus do so via an Intersil CDP68HC68S1 IC chip which translates SPI to CCD (A datasheet is provided below).
Electrical: Two wire centered 5v Differential signaling.
Termination: 120 Ohm Resistor
Bit Framing: Asynchronous Serial (RS232)
Baud: 7812.5 (1MHz / 128)
US Patent CCD Bus File:United States Patent 4706082 CCD Bus.pdf
Intersil CDP68HC68S1 Datasheet File:Fn1918.pdf