Compass: Description and Operation

COMPASS MINI-TRIP COMPUTER
The Compass Mini-Trip Computer is located in the premium overhead console on models equipped with this option. Two Compass Mini-Trip Computer units are available. One unit is used on vehicles not equipped with the Vehicle Theft Security System (VTSS) option, and the other is used on vehicles with the VTSS option. Both Compass Mini-Trip Computer units include the electronic control module, a Vacuum-Fluorescent Display (VFD), a compass flux-gate unit and two push button function switches.

Compass mini-trip computer units for vehicles equipped with the VTSS include a red Light-Emitting Diode (LED) on their electronic circuit board. This LED protrudes through the bottom of the lens on the front of the overhead console unit, and serves as the security indicator lamp. Refer to Security Indicator Lamp in the Description and Operation of Vehicle Theft/Security Systems for more information on this feature.

The Compass Mini-Trip Computer module contains a central processing unit and interfaces with other electronic modules in the vehicle on the Chrysler Collision Detection (CCD) data bus network. The CCD data bus network allows the sharing of sensor information. This helps to reduce wire harness complexity, reduce internal controller hardware, and reduce component sensor current loads. At the same time, this system provides increased reliability, enhanced diagnostics, and allows the addition of many new feature capabilities.

The Compass Mini-Trip Computer provides several electronic functions and features. Some of the functions and features that the Compass Mini-Trip Computer module supports and/or controls, include the following display options:

Compass/Temperature Display
This display provides one of eight compass readings to indicate the direction the vehicle is facing and the outside temperature. Pressing the US/M button for more than 10 seconds will toggle to the Compass/Compass in Degree Display. This display provides one of eight compass readings to indicate the direction that the vehicle is facing and provides the compass direction in degrees (0 to 359 °) North is 0 °, East is 90 °, South is 180 ° and West is 270 °.

Trip Odometer (ODO)
Shows the distance traveled in miles or km since the last reset.

Average Fuel Economy (AVE ECO)
Shows the average fuel economy in MPG (miles per gallon) or L/1OOKm since the last reset.

Instantaneous Fuel Economy
Shows the instantaneous fuel economy in MPG (miles per gallon) or L/100 Km.

Distance to Empty (DTE)
Shows the estimated distance that can be traveled with the fuel remaining in the tank. This level calculated using the MPG multiplied by the Fuel Tank Level.

Elapsed Time (ET)
Shows the accumulated ignition on time whenever the CMTC is powered up until a reset takes place.

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 and vice versa.

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.

Blank Screen - the compass mini-trip VFD is turned off.

The ambient temperature sensor is hard wired to the Compass Mini-Trip Computer module. Data input for all other Compass Mini-Trip Computer functions, including VFD dimming level, is received through CCD data bus messages. The Compass Mini-Trip Computer uses its internal programming and all of these inputs to calculate and display the requested data. If the data displayed is incorrect, perform the self-diagnostic tests. If these tests prove inconclusive, the use of a DRB III scan tool and the proper Diagnostic Procedures are recommended for further testing of the Compass Mini-Trip Computer module and the CCD data bus.

The Compass Mini-Trip Computer module cannot be repaired, and is available for service only as a unit. If faulty or damaged, the complete module must be replaced.

The Compass Mini-Trip Computer only operates with the ignition switch in the ON position. When the ignition switch is turned to the ON position, all of the segments in the Compass Mini-Trip Computer VFD will be turned on for one second, then the display will return to the last function being displayed before the ignition was turned to the OFF position. With the ignition switch in the ON position, momentarily depressing and releasing the Step push button switch will cause the compass-mini-trip computer to change its mode of operation, and momentarily depressing and releasing the U. S./Metric push button will cause the unit to toggle between U. S. and Metric measurements. While in either compass mode, depressing the U. S./Metric push button for more than ten seconds will toggle the display between the compass/temperature and the compass/compass in degrees modes.

This Compass Mini-Trip Computer features several functions that can be reset. If both the Step and U. S./Metric push buttons are depressed at the same time with the ignition switch in the ON position, the trip computer information that can be reset is reset. Depressing and releasing the Step and U. S./Metric push buttons at the same time for more than 100 milliseconds, but not more than one second while in any display mode (except the compass/temperature mode) will cause a local reset. A local reset affects only the function currently displayed. See the Reset Chart below for more information on this feature. Performing a local reset while in the compass/temperature mode enters the module into the compass variance setting mode.

Depressing and releasing the Step and U.S./Metric push buttons at the same time for more than two seconds while in any display mode (except the compass/temperature mode) will cause a global reset. A global reset changes all of the trip computer functions that can be reset.

For more information on the features and control functions of the Compass Mini-Trip Computer, see the owner's manual in the vehicle glove box.

COMPASS
While in the compass/temperature mode, the compass will display the direction in which the vehicle is pointed using the eight major compass headings (Examples: north is N, northeast is NE), along with the outside ambient temperature. When the compass unit is placed in the compass/compass in degrees mode, the compass will display the direction the vehicle is heading using the eight major compass headings and in degrees (0 to 359 degrees). North is 0 degrees, East is 90 degrees, South is 180 degrees and West is 270 degrees. It will not display the headings in minutes or seconds.

The self-calibrating compass unit requires no adjusting in normal use. The compass unit will compensate for magnetism the body of the vehicle may acquire during normal use. However, avoid placing anything magnetic directly on the roof of the vehicle. Magnetic mounts for an antenna, a repair order hat, or a funeral procession flag can exceed the compensating ability of the compass unit if placed on the roof panel. If the vehicle roof should become magnetized, the demagnetizing and calibration procedures found in this may be required to restore proper compass operation.

Compass Calibration
This is a Fast Auto-Cal compass that manually enters the calibration mode when the US/M and Step buttons are pressed for more than 6 seconds in the Compass/Temperature screen. The 'CAL' will illuminate to indicate the compass is in calibration mode. Drive the vehicle around in all four compass directions, such as driving around a street block several times or driving in 2-3 circles with a slow to medium speed. When the calibration process is completed, the 'CAL' will go OFF and the compass will function normally. The calibration should take place in an area that is leveled and minimum of 50 feet away from metal objects, power lines, buildings and large steel structures.

If the 'CAL' message remains in the display, either there is excessive magnetism near the compass, or the unit is faulty. If the wrong direction is still indicated in the compass display, the area selected for calibration may be too close to a strong magnetic field. If the compass cannot be calibrated, further diagnosis is necessary.

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. Simultaneously press both the US/M and STEP button for 0.1 to 2 seconds. The VAR indicator will light up and the current zone number will be displayed. Press STEP button to select the proper variance zone as shown on the map. After 5 seconds of inactivity, the displayed zone will be automatically set, and normal operation will resume.