Trip Computer: Description and Operation

DESCRIPTION
The compass mini-trip computer is located in the overhead console on models equipped with this option. The compass mini-trip computer units include the electronic control module, a Vacuum-Fluorescent Display (VFD), a compass sensor unit and two push button function switches.

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 and temperature - provides the outside temperature and one of eight compass readings to indicate the direction the vehicle is facing.
- Trip odometer (TRIP ODO) - shows the distance travelled since the last trip computer reset.
- Average fuel economy (AVG ECO) - shows the average fuel economy since the last trip computer reset.
- Instant fuel economy (ECO) - shows the present fuel economy based upon the current vehicle distance and fuel used information.
- Distance to empty (DTE) - shows the estimated distance that can be travelled with the fuel remaining in the fuel tank. This estimated distance is computed using the average miles-per-gallon from the last 30 gallons of fuel used.
- Elapsed time (ET) - shows the accumulated ignition-on time since the last trip computer reset.
- 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 as described. If these tests prove inconclusive, the use of a DRB 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. This unit includes the push button switches and the plastic module and display lens. If any of these components is faulty or damaged, the complete compass mini-trip computer module must be replaced.

OPERATION
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 off 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.

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 for more than one second with the ignition switch in the On position, the trip computer information that can be reset is reset. However, the reset will only occur if the function currently displayed is a function that can be reset. The functions that can be reset are: TRIP ODO, AVG ECO, and ET.

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 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 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,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 vanance 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.