CCD BUS SYSTEM
The Chrysler Collision Detection (CCD) bus is a pair of twisted wires traveling from module-to-module receiving and delivering coded information. The code identifies the message and its importance. When multiple messages attempt to access CCD bus at once, code assigns priority ranking.
The 2 twisted wires used by the CCD bus system are called bus "+" (positive) and bus "-" (negative). Both wires carry approximately 2.5 volts. The network consists of some modules with "bias" and some with "termination".
Bias is the part of the voltage divider network which places both bus "+" and bus "-" at 2.5 volts. Termination is the part of the circuitry required to complete the voltage divider network and also provide some electromagnetic protection for the CCD bus. Terminations in all CCD applications have approximately 120 ohms resistance.
MECHANICAL INSTRUMENT CLUSTER (MIC)
Instrument cluster includes a speedometer, tachometer, fuel gauge, oil pressure gauge, water temperature gauge, voltmeter and a series of warning lights.
Powertrain Control Module (PCM) sends signals necessary for the cluster to position gauges. Cluster receives these messages from CCD bus and translates them into gauge positions. BCM sends status of all indicator lights and dimming level to instrument cluster over CCD bus when ignition switch is in RUN or START positions.
Malfunction (CHECK ENGINE) indicator light status is sent to BCM from PCM over CCD bus. Vacuum fluorescent odometer/trip display works when ignition switch is in RUN or START positions. BCM stores mileage information that odometer displays. If CCD bus is not functioning, odometer will display dashes instead of the mileage numbers. BCM sends mileage message and dimming level message to vacuum fluorescent display when ignition switch is in the ON position. All other instrument cluster features only work when the ignition switch is in the RUN position.
OVERHEAD TRAVEL INFORMATION SYSTEM (OTIS)
The OTIS provides vehicle operator with supplementary information on a Vacuum Fluorescent Display (V). The OTIS is located in overhead console. Vehicle operator selects and resets display functions through the use of 4 buttons (US/M, STEP, C/T and RESET). The OTIS obtains most of its information from the CCD bus.
The OTIS powers up when it senses vehicle (battery) voltage on the ignition input circuit. The OTIS blanks the display, then illuminates all segments of the VFD. During this time, the OTIS sends and receives information over CCD bus to determine what to display after its 2 second initialization. The OTIS displays dashes (- -) for any of the screens for which it did not receive bus messages during the 2 second initialization. Dashes will be replaced by valid information if and when it is received.
VEHICLE THEFT SECURITY SYSTEM (VTSS)
VTSS monitors vehicle doors, hood, trunk key cylinder and ignition for unauthorized operation/entry. When alarm is triggered, the horn will sound for 3 minutes and the parking lights will flash for 15-18 minutes.
When an unauthorized entry into vehicle occurs, the VTSS module signals Powertrain Control Module (PCM) via CCD bus that it is not okay to start the engine. The PCM then "zeros out" the pulse width of the fuel injectors, thus preventing the engine from starting (start/stall condition). The engine will NOT start until VTSS is disarmed.
Initialization & Verification
An initialization procedure, included in VTSS, requires that vehicle record 20 engine cranking cycles before allowing VTSS module to function. For this reason, VTSS requires verification. To verify VTSS, perform the following: Open driver's door (all others closed). Remove ignition key. Lock doors with power door lock switch. Close driver's door. If VTSS SET light flashes, system is armed and operational. If VTSS SET light does not flash, 20 engine cranking cycles have not occurred or there is a problem with VTSS.
Manual Override Mode & Tamper Alert Mode
The VTSS will not arm if the doors are locked using the key or the manual lock control (manual override mode). If horn sounds 3 times when either front door is unlocked, the alarm was activated/triggered (tamper alert mode).
GENERAL PRECAUTION
| CAUTION | When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in the GENERAL INFORMATION section before disconnecting battery. |