Body Systems
CCD BUSThe Chrysler Collision Detection multiplex system (CCD Bus) is a twisted pair of wires which travel from module to module receiving and delivering coded information. The code is designed to identify the message it represents as well as the importance of the message. When there are multiple messages attempting to access the CCD bus at one time, the code is used to determine which one has higher priority and is allowed access to the bus first.
The two wires (DO1 and D02) used by the CCD system are generally called bus + and bus -. Both bus wires have a measurable voltage level of roughly 2.5 volts. In order to maintain the 2.5 volts on each line and provide a means of transportation for the coded messages there must be a voltage divider network consisting of modules with bias and others with termination. Bias is the part of the voltage divider network which places both bus + and bus - at 2.5 volts. Termination is the circuitry required to complete the voltage divider network and also provide some electromagnetic protection for the bus.
C2D BUS TESTING
A bus problem will show up in three basic forms when using the DRBII.
Despite the fact that the vehicle passed the automatic bus test a "NO RESPONSE" message may be displayed in place of an expected value on the DRBII. This will occur whenever a bus wire is open or poorly connected at a module. It will also appear if ground or the power supply is missing at certain modules. Finally the "NO RESPONSE" message may appear if the ignition has been turned off and the body computer has timed out. This makes it fairly impossible to use the DRBII to determine where the problem is until the reason for a "NO RESPONSE" message is found and corrected.
Secondly, there are major bus failures such as "SHORT TO GROUND", "SHORT TO BATTERY", "SHORT TO 5 VOLTS", and "BUS (+) & BUS (-) SHORTED TOGETHER". Typically any of these major failures could cause anything from an ENGINE NO START to a blank message screen on the EVIC Panel. The automatic bus test will not complete or allow access to further system tests at this point and the red light on the DRBII will come on.
"NO TERMINATION", "BIAS LEVEL TOO HIGH", "BIAS LEVEL TOO LOW", "NO BUS BIAS", "BUS (-) OPEN", "BUS (+) OPEN", "BUS (+) & BUS (-) OPEN", and "NOT RECEIVING BUS MESSAGES CORRECTLY" are the bus messages which, while critical and able to prevent the bus from operating properly, will allow the DRBII to present them on the message screen and then drop through into the next level of testing with no red light. The only interference in testing will come when trying to access a module which is directly related to or causing the bus failure to occur, a "NO RESPONSE" message will appear.
BODY CONTROLLER
There is only one Body Controller available in 1990 regardless of the complexity of the system. The body controller receives information from the Engine Node regarding brake fluid level, engine coolant level, and engine oil level. Exterior lamps are monitored by the Lamp Outage Module. Should a problem occur with a head lamp, tail lamp, or brake lamp, the lamp outage module senses the discrepancy and will report the condition to the body controller. The body controller also provides power or ground for a wide variety of systems and uses the voltage drop to monitor the system. The body controller is the only module which has the capability of providing bias and termination on the CCD bus.
The body controller is used to store odometer information displayed in the electronic instrument cluster.
When replacement of the body controller is required, contact a qualified service center to obtain an exchange body controller.
E.V.I.C. PANEL MONITOR
The Electronic Vehicle Information Center (E.V.I.C. panel monitor) is a module located in the dash (same location as the Traveler) and is used to provide the driver with supplemental information such as time, outside temperature, compass direction, and fuel economy. The E.V.I.C. panel also receives messages (for reference only; see Test 3 for list of messages) from other modules on the CCD bus regarding the status of a wide variety of systems and components. Any failure of a monitored system results in a warning message on the E.V.I.C. panel.
To set the E.V.I.C. Panel compass use the following procedures. If the vehicle is equipped with a Compass/Temp Module along with an EVIC Panel, the compass heading and variance can be set from either of the two Modules. Place the E.V.I.C. Panel in "TEMP" mode. Press and hold the "TEMP" and "SET" buttons for (5 to 6) seconds. An asterisk will appear in the upper right hand corner of the display. After (5 to 6) seconds the display will change and toggle between messages. Press the "TEMP" button once. The E.V.I.C. will begin to display "SETTING COMPASS". The "SETTING COMPASS" mode will be displayed for up to (60) sixty seconds while compass is calibrating. When the E.V.I.C. has finished, the display will toggle between "FACE CAR OPPOSITE" and "DIRECTION PRESS TEMP". Turn the car around 180 degrees in the opposite direction and press the "TEMP" button once. The E.V.I.C. will display "SETTING COMPASS" again. The display will return to normal operation automatically when the calibration process has been completed any variance has been reset.
It is necessary to set the variance on the E.V.I.C. Panel when the compass has been calibrated. To do this place the E.V.I.C. panel in the "TEMP" mode Press and hold the "TEMP"and "SET" button for (5 to 6) seconds. An asterisk will appear in the upper right hand corner of the display. After (5 to 6) seconds the display will change and begin to toggle between "SET COMP PRESS TEMP" and "SET VAR PRESS INFO" and "TO EXIT PRESS TIME" press the info button. The display will indicate "SETTING COMPASS" for up to sixty (60) seconds. The display will now toggle between "FACE NORTH PRESS TEMP" and "TO EXIT PRESS TIME". Point the vehicle toward geographic North (use road map) and press the temp button. The display will indicate "SETTING COMPASS" for up to (60) sixty seconds. The display will return to normal operation automatically when calibration process has been completed.
To set the clock on E.V.I.C. Head Monitor refer to owners manual If the clock function can not be set replace Body Controller.
ELECTRONIC INSTRUMENT CLUSTER
The electronic instrument cluster is easily distinguished from the mechanical instrument cluster by its digital and linear displays. The electronic cluster receives virtually all of its information to the displays from the body controller and engine controller via the CCD multiplex system. The electronic cluster includes a digital speedometer, odometer, oil pressure gauge, coolant temperature gauge, fuel gauge, voltage gauge, and a series of warning indicator lamps to provide the driver with all the necessary information to insure that the vehicle is in perfect operating condition.
The electronic cluster has two forms of diagnostic routines that are used to isolate problems within the cluster: self-diagnostics, using the trip and trip reset buttons for access, and CCD bus diagnostics routines which require the use of a DRBII diagnostic tester. Successful completion of the self-diagnostic test indicate that the problem is in the CCD bus, interfacing modules, connectors, wiring harnesses, or sensors outside the cluster.
The body controller is used to store odometer information displayed on the instrument cluster and not the electronic cluster itself, therefore, when replacement of the electronic cluster is required, the odometer reading will not be affected.
MECHANICAL INSTRUMENT CLUSTER
The Mechanical Instrument Cluster operates the same way it has in previous years with exception of three functions operated by the body controller. These conditions are as follows:
1. SEAT BELT WARNING LAMP:
The body controller will turn on the seat belt warning lamp for 6 +/- 2 seconds when ignition is turned on.
2. LOW FUEL WARNING LAMP:
The body controller will turn on the low fuel lamp when the fuel tank is 2.773 gallons including tank reserve.
3. CHECK GAGES LAMP:
The body controller will turn on the check gages lamp when the engine controller issues a high temperature warning and/or a charging system failure via the CCD bus system
VEHICLE THEFT ALARM SYSTEM
The Vehicle Theft Alarm System (VTA) is a logic controlled system, using an electronic module that monitors the vehicle doors, hood, trunk, key cylinder, and ignition for unauthorized operation.
This system is composed of the Vehicle Theft Alarm Control Module (VTA), two door ajar switches, hood ajar switch and striker, trunk key cylinder sensing switch, two door key cylinder disarming switches, instrument panel set lamp, Engine Controller, horn and horn relay, park and tall lamps, power door lock circuits, and ignition switch. When an unauthorized entry has occurred the Vehicle Theft Alarm Module will send a message via the CCD bus to the Engine Controller that it is not OK to start the engine. The engine controller will then zero out the pulse width to the fuel injectors after the engine has been started, shutting down the engine (start and stall condition).
The Vehicle Theft Alarm Control Module (VTA) has the capability of providing bias on the CCD bus when the Body Controller is powered down.
To avoid both an audible alarm and engine kill feature causing a problem in the assembly plant an initialization procedure was included in the system. This procedure requires that the vehicle has 20 engine cranks recorded, which means, systems will not be functional on all vehicles and will require dealer verification. System can be verified as follows:
1. Open driver's door
2. Remove ignition keys (keep in hand)
3. Lock doors with power door lock switch
4. Close driver's door
5. If instrument panel theft alarm "set", lamp flashes, system is operational and verified. If not, 20 engine cranks have not occurred, or there is a problem with the Vehicle Theft Alarm system.
When an engine controller has been replaced, 20 engine cranks must be reached before theft alarm becomes operational.
TRAVELER
The Traveler is a module located in the instrument panel just right of the steering column (same location as the EVIC Panel) and is used to provide the driver with navigational information such as Fuel Economy (average), Fuel Economy (instant), DTE (distance to empty), ET (estimated time), and ODO (trip odometer). The Traveler receives messages from the body controller and the engine controller via the CCD bus regarding fuel and odometer information.
COMPASS/TEMP MODULE
The Compass/Temp Module is located in the overhead console and is used to provide the driver with vehicle direction and the current outside temperature. If a vehicle is equipped with an EVIC Panel and a Compass/Temp Module the Compass/Temp Module sends navigational information to the EVIC panel on the CCD bus. The Engine Node provides the Compass/Temp Module with the outside temperature. When the Compass/Temp Module has been replaced it may be necessary to reset the calibration following the steps below. If a vehicle is equipped with an EVIC Panel along with a Compass/Temp Module the compass heading and variance may be set from either of the two modules.
1. Depress and hold down both the compass/temp button and the U.S./Metric button.
2. The display will go off and after 5 seconds the VAR light will come on. Continue to hold both buttons down.
3. In approximately 10 seconds, the CAL light will come on. Release both buttons and the display will show the heading and outside temperature.
4. Drive the vehicle one to three complete circles. The CAL light will then go off, indicating the compass is calibrated.
If the compass portion of the display is not lit, or compass readings are not accurate after calibration, the vehicle may have too much magnetism for the compass to be accurate or the compass circuity is not operating properly. Follow the Variance procedure below.
Variance Settings:
Variance is the difference between magnetic North and geographic North. In some areas the difference between magnetic and geographic North is great enough to cause the compass to give false readings. If this occurs, the variance must be set. To set the variance, depress and hold down both the Compass/temp button and the U.S./Metric button. The display will go off and after 5 seconds the VAR light will come on. Release both buttons, using the zone map (FIG.1) to find your geographic location, note the zone which you are in. Press the U.S./Metric until the zone number appears on the display. press the compass/temp button to enter your zone number. Do not attach magnetic devices, such as magnetic CB antennas to the vehicle roof, as they can cause the compass to give false readings. If it is necessary to Degauss the vehicle follow the procedures in T.S.B. 08-14-87 supplement A.