Compass: Description and Operation
COMPASS/MINI-TRIP COMPUTER
The Compass/Mini-Trip Computer (CMTC) is in the overhead console. It displays the following information:
- Compass direction
- Current outside temperature
- Elapsed Time (ET)
- Distance To Empty (DTE)
- Average Fuel Economy (AVE ECO)
- Instantaneous Fuel Economy (ECO)
- Trip Odometer (ODO)
All of the information required by the CMTC except the ambient temperature and compass direction is transmitted over the CCD bus.
The CMTC can perform an independent self-test. This can be accomplished by using either the DRB or pressing both US/M and STEP buttons and then turning the ignition key on. All segments of the CMTC should light while the CMTC checks its internal function. If there are internal failures, the CMTC will display "FAIL." If there is a problem with the CCD communication, the CMTC will display "CCD." Refer to the "Compass/Mini-Trip" for further diagnosis.
Testing and Inspection
Setting The Compass
The compass/mini-trip module is self-calibrated and requires no adjustment. The word CAL will be displayed to indicate that the compass is in the fast calibrating mode. CAL will turn off after the vehicle has gone in three complete circles without stopping, in an area free of magnetic disturbance.
If the module displays the temperature while the compass is blank, or displays a false reading, the vehicle must be demagnetized.
If the compass still goes blank after the vehicle is demagnetized, the compass/mini-trip module must be replaced.
Setting The Compass Variance
Variance is the difference between magnetic north and geographic north. To determine the variance for the area you are in, refer to the zone map. The number shown for your area is the variance number for your area.
1. Set the compass/mini-trip console to compass/ temperature mode.
2. Press and hold down both the US/METRIC button and the STEP button for 5 seconds.
3. The VAR light will come on and the last variance setting will be displayed.
4. Enter the correct variance number by pressing the US/M button.
5. Press the STEP button to set the zone number and resume normal operation.
NOTE: DO NOT ATTACH ANY MAGNETIC DEVICE SUCH AS A MAGNETIC CB ANTENNA TO THE VEHICLE. THIS CAN CAUSE THE COMPASS TO GIVE FALSE READINGS.
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). It does not display the headings in actual degrees.
The self-calibrating compass unit requires no adjusting in normal use. The only calibration that may prove necessary is to drive the vehicle in three complete circles, on level ground, in not less than 48 seconds. This will reorient the compass unit to its vehicle,
The compass unit also 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. Magnetic bit drivers used on the fasteners that hold the assembly to the roof header can also affect compass operation. If the vehicle roof should become magnetized, demagnetizing and calibration may he required to restore proper compass operation. See Compass Calibration or Compass Demagnetizing Service Procedures. The compass, trip computer, and thermometer display module cannot be repaired, and is only available for service as a unit. If faulty or damaged, the complete module must be replaced. The push button (Step and U. S./Metric) switch module is serviced separately.