General Information

Module Locations:

SYSTEM DESCRIPTION AND FUNCTIONAL OPERATION
The body system on the 1999 Durango consists of five modules that communicate over the CCD bus (Chrysler Collision Detection multiplex system). There are two additional modules, the Powertrain Control Module (PCM) and the Controller Anti-Lock Brake (CAB) that are not part of the body system, but do utilize the CCD bus for communication, The CAB also utilizes the bus for diagnostics. The PCM sends and receives messages on the CCD bus, however diagnostics are performed through the Serial Communication Interface (SCI), the same as previous years. All of the information about the functioning of all the systems is organized, controlled, and communicated by the CCD bus, which is described in Vehicle Communication.

Through the CCD bus, information about the operation of vehicle components and circuits is relayed quickly to the appropriate module(s). All modules receive all the information transmitted on the bus even though a module may not require all the information to perform it's function. It will only respond to messages "addressed" to it through a binary coding process. This method of data transmission significantly reduces the complexity of the wiring in the vehicle and the size of wiring harnesses.

AIRBAG SYSTEM
The airbag system is designed to provide increased driver and passenger protection if the vehicle is involved in a front end collision. The system is most effective when used in conjunction with the seat belt system.

The Airbag Control Module (ACM) is an electronic module that monitors the airbag system for proper operation, stores diagnostic trouble code (DTCs), controls the airbag warning lamp and contains the sensor and actuator that is responsible for airbag deployment. There are no external impact sensors. The ACM is mounted on a special bracket that is fastened to the floor of the truck at the bottom of the instrument panel. It is located forward of the console. The ACM provides diagnostic information (DTCs) to the technician through the DRB III via the CCD bus. Some circuits are tested continuously; others are checked only under certain circumstances. The warning lamp is driven with messages relayed to the Mechanical Instrument Cluster (MIC) from the ACM via the CCD bus.

The AIRBAG warning lamp is the only point at which "symptoms" of a system malfunction can be observed by the customer. whenever the ignition key is turned to the "RUN" or "START" position, the Airbag Control Module performs a lamp check by turning the AIRBAG warning lamp ON for 6-8 seconds. If the lamp remains OFF, it means that the ACM has checked the system and found it to be free of discernible malfunctions. If the lamp remains ON, there could be an active fault in the system or the circuit that operates the lamp may be shorted to ground. If the lamp comes ON and stays ON for a period longer than 6-8 seconds, then goes OFF, there is usually an intermittent problem in the system.

Perform the WARNING LAMP CIRCUIT OPEN procedure in this book to find the cause of any customer complaint regarding the AIRBAG warning lamp, such as:
- warning lamp does not illuminate
- warning lamp stays illuminated

WARNING: THE AIRBAG CONTROL MODULE CONTAINS THE IMPACT SENSOR, WHICH ENABLES THE SYSTEM TO DEPLOY THE AIRBAG. BEFORE ATTEMPTING TO DIAGNOSE OR SERVICE ANY AIRBAG SYSTEM OR RELATED STEERING WHEEL,STEERING COLUMN, OR INSTRUMENT PANEL COMPONENTS YOU MUST FIRST DISCONNECT AND ISOLATE THE BATTERY NEGATIVE (GROUND) CABLE. THEN WAIT TWO MINUTES FOR THE SYSTEM CAPACITOR TO DISCHARGE BEFORE FURTHER SYSTEM SERVICE. THIS IS THE ONLY SURE WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE TO DO THIS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.NEVER STRIKE OR KICK THE AIRBAG CONTROL MODULE, AS IT CAN DAMAGE THE IMPACT SENSOR OR AFFECT ITS CALIBRATION. IF AN AIRBAG CONTROL MODULE IS ACCIDENTALLY DROPPED DURING SERVICE, THE MODULE MUST BE SCRAPPED AND REPLACED WITH A NEW UNIT.

CENTRAL TIMER MODULE
The Durango utilizes a Central Timer Module (CTM). This system is available in a Base or Highline configuration. The Base CTM does not communicate on the CCD bus and will not be addressed. The CTM performs most of the typical functions a Body Control Module would perform.

The Highline CTM provides the following features:
- Remote Keyless Entry (RKE)
- Chime
- Courtesy Lamp controls/Illuminated Entry
- Power Door Locks
- Speed Sensitive Intermittent Wipers
- Enhanced Accident Response
- Vehicle Theft Security System (VTSS)

The module is located on the right side of the glove box behind a metal bracket. It contains a white 18-way and a green 14-way connector.

Chime system
The chime system is built into the CTM. The system also supports an external chime request from the instrument cluster. This feature allows the instrument cluster to request a chime from the CTM for seat belt, gauge problems and tell-tale warnings. There are two chime rates, Low; 50 ± 12 chimes per minute for reminders and High; 180 ± 12 chimes per minute for serious conditions that require immediate attention. The high rate chime sounds when the key is left in the ignition and the doors are open or the headlights are left ON. The low rate chime sounds for any of the other conditions. There is a variable rate feature that allows the chime to sound continuously for key-in and headlamp warning as long as the door is open. The seat belt warning chime is activated for approximately six seconds, and all other chime conditions will activate the chime once at the same time the warning light on the cluster is illuminated.

The chime will sound for the following conditions:
- Ignition OFF, key in ignition, driver's door open
- Ignition OFF, headlamps ON, driver's door open
- Seat belt warning
- Check engine lamp illuminated (after prove-out)
- Airbag lamp illuminated (after prove-out)
- Anti-lock lamp illuminated (after prove-out if equipped)
- Check gauges lamp illuminated
- Low fuel warning lamp illuminated
- Low washer fluid
- Door ajar

Compass Mini-Trip Computer (CMTC)
This system, located in the overhead console, displays information on outside temperature, compass direction and trip information.

Compass And Temperature Display
This display provides the outside temperature and one of eight compass readings to indicate the direction the vehicle is facing.

Trip Odometer (ODO)
Shows the distance traveled since the last reset.

Average Fuel Economy (AVE ECO)
Shows the average fuel economy in MPG (miles per gallon) or L/100Km since the last reset.

Instantaneous Fuel Economy
Shows the fuel economy for the last few seconds in MPG or L/100Km.

Distance to Empty (DTE)
Shows the estimated distance that can be traveled with the fuel remaining in the tank. This is calibrated using the MPG for the last few minutes.

Elapsed Time (ET)
Shows the accumulated ignition ON time since the last reset.

Step Button
Press this button to cycle through all the minitrip computer displays.

US/M Button
Press this button to convert all vehicle displays from US to Metric to US.

To Reset the Display
Press the Step and US/M buttons simultaneously for at least two seconds and all resettable conditions will be reset. This will occur only if a resettable function (AVG ECO, Trip Odometer, ET) is currently being displayed.

Automatic Compass Calibration
This compass is self calibrating which eliminates the need to manually set the compass. When the vehicle is new, the compass may appear erratic and the CAL symbol will be displayed. After completing three 360' turns in an area free from large metal or metallic objects, the CAL symbol will turn OFF and the compass will function normally.

Compass Variance
Compass Variance is the difference between Magnetic North and Geographic North. In some areas of the country, the difference between Magnetic and Geographic North is great enough to cause the compass to give false readings. If this occurs, the compass variance must be set.

To set the variance:
Turn the ignition ON and set display to Comp./Temp. While pressing the US/M button, press the STEP button for approximately five seconds. The "VAR" symbol will light and the last variance zone number will be displayed. Press the US/Metric Button to select the proper variance zone as shown on the map. Press the Step button to set the new variance zone and resume normal operation.

Enhanced Accident Response (Highline CTM Only)
If the Airbag Control Module (ACM) deploys the airbags, a message is transmitted over the CCD bus to the CTM module to unlock the doors. The interior lights will be turned ON when the vehicle speed message on the CCD bus indicates 0 mph or the message is not present. In addition to unlocking the doors, the door lock feature will be disabled for a predetermined amount of time following the deployment. Once the ignition key has been cycled to the "OFF" position, normal operation will resume.

Interior Lighting
The courtesy lights are controlled by the CTM. The door switches are inputs to the CTM and the courtesy lights are outputs. The glove box lamp the ash receiver lamp (if equipped) are not controlled by the CTM. They are hardwired to individual switches and fuses.

The highline CTM also provides for illuminated entry option. If the CTM detects an unlock signal from the RKE transmitter, a door disarm switch input or the door jamb switch input, the interior courtesy lights will be turned ON. The illuminated entry function is canceled if the CTM senses an ignition "ON" condition or the "lock" command from a valid key fob.

If a door is left open or turned ON by rotation of dimmer switch for more than fifteen minutes, the CTM will extinguish the lamps to avoid discharging the battery. If the lamps are turned ON by courtesy lamp switch, the CTM will not be able to turn them OFF.

The Durango utilizes an interior light defeat switch as an integral part of the headlamp switch.

Mechanical Instrument Cluster (MIC)
The MIC is available in 4 different versions. Two of the versions are Canadian clusters. There is a highline and a low line cluster available. The difference is the addition of a tachometer in the highline. In order to accomplish this, the fuel level gauge is reduced in size and oil pressure gauge is relocated. The cluster positions its gauges with bus messages received from the PCM. The odometer is a Liquid Crystal Display (LCD). The cluster will provide bus bias and the PCM provides termination.

The MIC has an internal diagnostic routing that can be accessed by pushing and holding the trip odometer while rotating the key to the ON position. The cluster will then place all the gauges at their calibration points and will light all the CCD driven tell-tales. It will also light all the segments of the LCD display for a visual verification check.

The MIC can verify communications with the PCM, ID the module, or change the country code by using options 1, 3, or 9 on the DRB III under the MIC menu. If there are faults found during the diagnostic routine, the cluster will report them on the LCD odometer display.

Power Door Locks
The CTM controls the door lock actuator assemblies to handle locking and unlocking with the key fob or interior switch. There is also a door lock inhibit feature that prevents power locking of the doors if the ignition is OFF, the door is open, and the key is in the ignition. Automatic or "rolling locks" are included as a DRB III, or customer programmable feature. If the vehicle is moving approximately 15 mph and approximately 10 degrees of throttle opening is seen by the PCM, (the PCM will send this info to the CTM via the CCD bus) indicating acceleration, the CTM will cycle the lock actuators to lock the doors.

RKE/VTSS
If the vehicle is equipped with Remote Keyless Entry (RKE), programming of additional transmitters and horn chirp are customer programmable features, The highline CTM provides for RKE and the Vehicle Theft Security System (VTSS). The base CTM is not able to provide these functions. The presence of either of these options dictates that the vehicle is equipped with a highline CTM. The VTSS system monitors the door ajar switches, liftgate and ignition switch to detect unauthorized entry into the vehicle. Once the vehicle is "armed", any one of these inputs can cause the VTSS system to be tripped. Once tripped, the horn and lights will pulse for 3 minutes and if an attempt is made to start the engine, it will start and stall. If the trigger condition is still present, the lights will continue to flash for an additional 15 minutes. After 15 minutes the system will stop pulsing the lights and return to the "armed" state. The cause of the last 4 alarm triggers is stored by the CTM and may be retrieved by the DRB III. The system may be disarmed by either an unlock command from a valid RKE key fob or by using a key in the lift gate or either door. Both front door key cylinders and the lift gate are equipped with disarm switches. There is also a VTSS lamp on the dash that provides information to the driver about the state of the vehicle theft system.

The RKE system is placed in the programming mode by the DRB, or by using the customer programming sequence. The system will store up to four key fob codes. Two fobs are supplied with the truck, additional fobs may be purchased through parts department. The additional fobs can be programmed with the DRB III, or by using the customer programming sequence. Through the DRB III, erasing and programming of one key fob without deleting the others is possible. If the key fob is stolen, all the fob codes stored previously may be erased to provide the owner of the vehicle with an extra sense of security.

Speed Sensitive Intermittent Wipers
The DN truck equipped with a highine CTM will utilize speed sensitive intermittent wipers. Only a highine CTM Will be able to support this feature. A base CTM will provide for intermittent wipers without the speed sensitive feature. The low and high speeds are controlled through the wiper stalk switch. The intermittent portion of the wiper control is handled by the CTM through the intermittent wiper relay. When the module detects a decrease in delay time as selected by the driver, an immediate wipe of the windshield takes place and the new delay interval is implemented.

Diagnostics
The CTM is fully addressable with the DRB III and it is the recommended method for diagnosis. The CTM reports 6 Diagnostic Trouble Codes. All of the inputs to the CTM can be read with the DRB and the outputs can be actuated.

VEHICLE COMMUNICATION
The Chrysler Collision Detection multiplex system (CCD bus) consists of a twisted pair of wires. These wires run from one module to another. They receive and deliver coded information between the modules. The information is coded to identify the message as well as the importance of the message. When there are multiple messages trying to access the CCD bus at one time, the code determines the message that has the highest priority, and is then allowed to access the bus first.

The two wires of the twisted pair that make up the CCD multiplex system are called "bus +" (bus plus) and "bus -" (bus minus) respectively. Each wire has a measureable 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 is a "voltage divider network" located in the module that supplies bus bias or voltage. Along with the module that supplies bias, some modules provide termination. Bias is the voltage necessary to make the bus operational. At least one point of termination is necessary, some systems may use more than one. Some modules are capable of both biasing and terminating. Termination in the circuitry (a 120 ohm resistor placed across the bus) is required to complete the voltage divider network circuit and also provide some electromagnetic protection for the bus. In this vehicle, the bias is supplied by the instrument cluster and termination is provided by the PCM and the instrument cluster. Without termination, voltage on the bus goes to approximately 5 volts on one wire and 0 volts on the other wire.

NOTE: Communication over the bus is essential to the proper operation of the vehicle's on-board diagnostic systems and the DRB III. Problems with the operation of the bus or DRB III must corrected before proceeding with diagnostic testing.

Bus Failure Messages
Short to Battery - Either or both of the bus wires are shorted to the battery potential, or

Open ground to any CCD bus module.

Short to 5 Volts - Either or both of the bus wires are shorted to a 5-volt potential.

Short to Ground - Either or both of the bus wires are shorted to ground.

Bus (+) L Bus (-) Shorted Together - The two bus wires are shorted together.

No Termination - The bus system has lost connection with all of its terminators.

Bus Bias Level Too Low - Either of both of the bus wire potentials are significantly below their normal 2.5 volts.

Bus Bias Level Too High - Either of both of the bus wire potentials are significantly above their normal 2.5 volts.

No Bus Bias - The bus system has lost connection with the Instrument Cluster.

Bus (+) Open - The bus (+) wire has lost connection with termination and/or bias.

Bus (-) Open - The bus (-) wire has lost connection with termination and/or bias.

Not receiving Bus Messages Correctly - The DRB cannot communicate over the bus and does not know why.

AIRBAG DIAGNOSTIC TROUBLE CODES
Airbag diagnostic trouble codes consist of active and stored codes. If more than one code exists, diagnostic priority should be given to the active codes.

Each diagnostic trouble code is diagnosed by following a specific testing procedure. The diagnostic test procedures contain step-by-step instructions for determining the cause of the trouble codes. It is not necessary to perform all of the tests in this book to diagnose an individual code.

Always begin by reading the diagnostic trouble codes using the DRB III. The procedure begins with AIRBAG TEST 1A-Identifying Airbag System Problems. This will direct you to the specific test(s) that must be performed.

Active diagnostic trouble codes for the airbag system are not permanent and will change the moment the reason for the code is corrected. In certain test procedures, diagnostic trouble codes are used as a diagnostic tool.

Active Codes
The code becomes active as soon as the malfunction is detected and stored after one minute of occurrence or key-OFF, whichever occurs first. An active trouble code indicates an on-going malfunction. This means that the defect is currently there every time the airbag control module checks that circuit/function. It is impossible to erase an active code; active codes automatically erase by themselves when the reason for the code has been corrected.

With the exception of the warning lamp trouble codes or malfunctions, when a malfunction is detected, the airbag lamp remains lit for a minimum for 12 seconds or as long as the malfunction is present.

Stored Codes
Airbag codes are automatically stored in the ACM's memory after one minute of occurrence or when the ignition is turned OFF. The exception is the "Loss of Ignition Run Only" code which is an active code only.

A "stored" code indicates there was an active code present at some time. However, the code currently may not be present as an active code, although another active code could be.

When a trouble code occurs, the airbag warning lamp illuminates for 12 seconds minimum (even if the problem existed for less than 12 seconds). The code is stored, along with the time in minutes it was active, and the number of times the ignition has been cycled since the problem was last detected.

The minimum time shown for any code will be one minute, even if the code was actually present for less than one minute. Thus, the time shown for a code that was present for two minutes 13 seconds, for example, would be three minutes.

If the malfunction is detected a diagnostic trouble code is stored and will remain stored as long as the malfunction exists. When and if the malfunction ceases to exist, an ignition cycle count will be initiated for that code. If the ignition cycle count reaches 100 without a reoccurrence of the same malfunction, the diagnostic trouble code is erased and that ignition cycle counter is reset to zero. If the malfunction reoccurs before the count reaches 100, then the ignition cycle counter will be reset and the diagnostic trouble code will continue to be a stored code.

If a malfunction is not active while performing a diagnostic test procedure, the active code diagnostic test will not locate the source of the problem. In this case, the stored code can indicate an area to inspect.

If no obvious problems are found, erase stored codes, and with the ignition "on" wiggle the wire harness and connectors, rotate the steering wheel from stop to stop. Recheck for codes periodically as you work through the system. This procedure may uncover a malfunction that is difficult to locate.

Airbag Diagnostic Trouble Codes
The airbag control module may report any of the following diagnostic trouble codes.

For the following codes, replace the Airbag Control Module (ACM) even if set intermittently:
- ACM Accelerometer
- Internal Diagnostic 1
- Internal Diagnostic 2

For the following codes, replace the Airbag Control Module (ACM):
- ACM Output Driver
- ACM Stored Energy Logic
- ACM Stored Energy Driver
- ACM Stored Energy Passenger
- Internal Diagnostic 3
- Internal Diagnostic 4
- Safing Sensor Shorted
- Warning Lamp Driver Error

For these codes, refer to the appropriate diagnostic procedure:
- Driver Squib Open
- Driver Squib Shorted
- Loss of Ignition Run Only
- Loss of Ignition Run/Start
- No CCD Communication
- Passenger Squib Circuit Open
- Passenger Squib Circuit Shorted
- Either Squib Terminal Short to Battery
- Either Squib Terminal Short to Ground
- Warning Lamp Circuit Open
- Warning Circuit Shorted

Central Timer Module Diagnostic Trouble Codes
- Door Disarm Switch Failure
- Door Lock Switch Failure
- Door Unlock Switch Failure
- Wiper Park Switch Failure
- EEPROM Checksum Failure
- Internal ROM Test Failure