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For additional information on the Base CTM refer to Instrument Panel, Gauges and Warning Indicators / Audible Warning Device. Audible Warning Device

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 PCI bus. Some circuits are tested continuously; others are checked only under certain circumstances. The warning lamp is driven with messages relayed to the Electro/Mechanical Instrument Cluster (EMIC) from the ACM via the PCI 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.

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.

Seat Belt Tensioner
Front seat belt systems incorporate Tensioner Modules (SBT). At the onset of an impact event each tensioner uses a pyrotechnic device, which is triggered simultaneously with the airbags, to rapidly retract the seat belts. With the slack removed, the occupant's forward motion in an impact will be reduced as will the likelihood of contacting interior components. After an impact that deploys the airbag, the seat belt tensioner assembly must be replaced.

The ACM module monitors the Seat Belt Tensioners circuit resistance and reports active and stored DTC's if any problem is found.

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.

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 of 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 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.

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 a 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, that 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.

AUDIO SYSTEM
The factory installed radio receiver communicates on the Programmable Communication Interface (PCI) data bus network through a separate two-way wire harness connector. This is used for the remote radio switches that are mounted to the steering wheel, and also used for radio diagnosis with the DRB III.

The remote radio switches are resistor multiplexed units that are hard wired to the CTM through the clockspring. The CTM monitors the status of the remote radio switches and sends the proper switch status messages on the PCI data bus network to the radio receiver. The electronic circuitry within the radio is programmed to respond to these remote radio switch status messages by adjusting the radio settings as requested.

When troubleshooting output shorts or "output" error messages, the following applies:
On radios without an external amplifier, the term "output" refers to the path between the radio and the speaker. This type of circuit can be monitored all the way through the speaker connections by the radio assembly. When the radio displays a shorted output DTC with this type of system, the speaker, radio or wiring could be at fault. The output DTC could refer to a front or rear output or a left or right output. The reason for the difference is the pairing of the output sections of the radio. Some are paired left and right, others are paired front and rear.

On radios with an external amplifier, the term "output" refers to the circuit between the radio connector and the amplifier. The radio is capable of monitoring only this portion and can tell nothing about the circuit between the amplifier and the speakers. Consequently, a shorted output DTC on this type of system would only refer to this circuit. A faulty speaker could not cause this DTC.

CENTRAL TIMER MODULE
The Durango (DN) utilizes a Central Timer Module (CTM). This system is available in a Base or Highline configuration.

The CTM performs most of the typical functions a Body Control Module would perform.

The Base and Highline CTM provides the following features:
- Battery Saver Functions For Exterior and Interior Lamps
- Cargo Lamps
- Chime Warning
- Courtesy Lamps
- Dome Lamps
- Dome Defeat
- Door Ajar Switch Status
- Fog Lamps
- Head Lamp Time Delay
- Intermittent Wiper Controls
- Low and High Beam Head Lamps
- Optical Horn
- Park Lamps

Additional features of Highline CTM
- Central Locking (VTSS)
- Door Lock Inhibit
- Driver Door Unlock
- Enhanced Accident Response
- Power Door Locks
- Remote Radio
- Remote Keyless Entry
- Vehicle Theft Alarm (VTSS)

The Central Timer Module is located behind the left side kick panel. It contains 26-way, 16-way and 12-way connectors.

CHIME SYSTEM
The chime system is built into the CTM. There are two chime rates, Low: 50 chimes per minute for reminders and High: 180 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 driver's door is open or if the headlights or the courtesy lights 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 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
- Ignition OFF, courtesy lamps ON, driver's door open
- Seat belt warning (after prove-out)
- Malfunction Indicator lamp (MIL) illuminated (after prove-out)
- Airbag lamp illuminated (after prove-out)
- Check gauges lamp
- Low fuel warning
- Low washer fluid lamp
- Door ajar warning
- Transmission temperature lamp
- Turn signal on reminder warning
- Button pushed on compass mini-trip computer

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/100 Km since the last reset.

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

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 mini-trip 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, ECO, 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.

ELECTRO/MECHANICAL INSTRUMENT CLUSTER (EMIC)
The Instrument Cluster contains a Fuel, Voltmeter, Coolant Temp, and Oil Pressure gauge, a Tachometer and a Speedometer. With the exception of the Voltmeter, the cluster positions the gauges with PCI Bus messages received from the PCM. The Voltmeter operates directly off of the Fused B+ Switched Ignition Output circuit that supplies ignition voltage for the cluster.

The Instrument Cluster also contains warning indicators that are illuminated by hard wired inputs or by messages received from other modules on the PCI Bus.

The Trip/Total Odometer is a Vacuum Fluorescent Display (VF) that is controlled by PCI Bus messages received from the PCM.

The cluster illumination lamps are hard wired in the Instrument Cluster. When the Park or Headlamps are turned ON, the cluster receives a dimmed battery feed from the Headlamp Switch. The cluster I/O Processor controls the VF display dimming and also sends dimming level messages on the PCI Bus.

The EMIC will communicate with the DRB III to display PCI Engine Info, PCI Bus Info, and certain input/outputs. Cluster diagnostic capabilities that the DRB III will actuate are limited to the Cluster Calibration Points for the gauges. The DRB III can also extract active and stored Diagnostic Trouble Codes (DTC) from the Instrument Cluster.

The EMIC is also capable of performing a diagnostic Self-Test that is actuated by depressing and holding the Odometer trip reset stalk while cycling the ignition from the OFF to the ON position. After the cluster Odometer displays CHEC, releasing the reset stalk begins the test. The cluster will then position all of the gauges at specified calibration points and will illuminate all the PCI Bus controlled indicators. The cluster will also illuminate each segment of the VF display.

The EMIC can verify communications with the PCM, ID the module, or change the country code using the DRB III.

ENHANCED ACCIDENT RESPONSE (HIGHLINE CTM ONLY)
If the Airbag Control Module (ACM) deploys the airbags, a message is transmitted over the PCI bus to the CTM module to unlock the doors. The interior lights will be turned ON when the vehicle speed message on the PCI 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.

EXTERIOR LIGHTING
The low and high beam headlamps are controlled directly by an output from the Central Timer Module (CTM). The park lamps and fog lamps (on vehicle so equipped) are controlled via external relays that are energized by the CTM. The headlamp switch provides the control signal through the multifunction switch to the CTM, which indicates low or high beam operation.

The Optical Horn (Flash to Pass) feature operates both the high beam and low beam headlamps.

The CTM provides the Headlamp Time Delay feature. To start the delay, turn the ignition OFF while the headlamps are ON. Then turn the headlamp switch to the OFF position. This has to be done within 45 seconds of the ignition being turned OFF. The headlamps will remain ON for 60 ± 5 seconds. If during this delay period the headlamp switch is turned ON and then OFF, or ignition switch is turned ON delay will be canceled and they will turn OFF immediately. During the delay period, only headlamps are turned ON and park lamps/fog lamps are turned OFF.

The CTM also provides battery protection to avoid wearing down the battery if the customer leaves the park lamps or headlamps ON for extended period of time with the ignition OFF. If the park lamps or headlamps remain ON for more than 5 minutes while the ignition is OFF, the headlamps and park lamps shall be turned off and the input causing the lamps to be ON will be ignored until the input is corrected. Once the 5 minute timeout has extinguished the headlamps and park lamps, any change in the ignition switch, door ajar switches, headlamps switch or park lamp switch will reset the 5 minute timer and return the headlamps and park lamps to normal operation.