Compass Description And Operation; Thermometer Description And Operation; Reading And Courtesy Lamp Description And Operation - Jeep Cherokee 2000 Service Manual

8V - 2 OVERHEAD CONSOLE SYSTEMS
DESCRIPTION AND OPERATION (Continued)
Some of the functions and features that the trip
computer supports and/or controls, include the fol-
lowing display options:
• Compass and temperature
• Trip odometer (ODO)
• Average fuel economy (AVG ECO)
• Instant fuel economy (ECO)
• Distance to empty (DTE)
• Elapsed time (ET)
• Blank display.
Momentarily depressing and releasing the Step
button when the ignition switch is in the On position
will cause the overhead console display to step
sequentially through the listed display options.
Momentarily depressing and releasing the U. S./Met-
ric button toggles the display between U. S. and Met-
ric measurements.
The push button (Step and U. S./Metric) switch
module in the overhead console is hard wired to the
trip computer. The compass flux-gate unit is integral
to the trip computer, compass, and thermometer dis-
play module unit. Data input for all other trip com-
puter functions is received through CCD data bus
messages. The trip computer uses its internal pro-
gramming and all of these inputs to calculate and
display the requested data. If the data displayed is
incorrect, see Trip Computer, Compass, and Ther-
mometer Display Module - Self-Diagnostic Test in the
Diagnosis and Testing section of this group. If these
tests prove inconclusive, the use of a DRB scan tool
and the proper Diagnostic Procedures manual are
recommended for further testing of the trip computer
and the CCD data bus.
The trip computer, compass, and thermometer dis-
play module cannot be repaired, and is only available
for service as a unit. If faulty or damaged, the com-
plete module must be replaced. The push button
(Step and U. S./Metric) switch module is serviced
separately.
COMPASS
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 magne-
tism the body of the vehicle may acquire during nor-
mal 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 pro-
cession flag can exceed the compensating ability of
the compass unit if placed on the roof panel. Mag-
netic 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 magne-
tized, demagnetizing and calibration may be required
to restore proper compass operation. See Compass
Calibration or Compass Demagnetizing in the Service
Procedures section of this group for these procedures.
The compass, trip computer, and thermometer dis-
play module cannot be repaired, and is only available
for service as a unit. If faulty or damaged, the com-
plete module must be replaced. The push button
(Step and U. S./Metric) switch module is serviced
separately.
THERMOMETER
The thermometer displays the outside ambient
temperature. The temperature
changed from Fahrenheit to Celsius using the U.
S./Metric button, located just rearward of the display
module. The displayed temperature is not an instant
reading of conditions, but an average temperature. It
may take the thermometer display several minutes
to respond to a major temperature change, such as
driving out of a heated garage into winter tempera-
tures.
When the ignition switch is turned to the Off posi-
tion, the last displayed temperature reading stays in
the thermometer unit memory. When the ignition
switch is turned to the On position again, the ther-
mometer will display the memory temperature if the
engine coolant temperature is above about 52° C
(125° F). If the engine coolant temperature is below
about 52° C (125° F), the thermometer will display
the actual temperature sensed by the ambient tem-
perature sensor. The thermometer temperature dis-
play update interval varies with the vehicle speed.
The thermometer function is supported by an
ambient temperature sensor. The sensor is mounted
outside the passenger compartment near the front
and center of the vehicle and is hard-wired to the
module. The ambient temperature sensor is available
as a separate service item.
The thermometer, compass, and trip computer dis-
play module cannot be repaired, and are only avail-
able 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 and ambient
temperature sensor are serviced separately.
READING AND COURTESY LAMP
All reading and courtesy lamps located in the over-
head console are activated by the door ajar switches.
When the doors are closed, the lamps can be individ-
ually activated by depressing the corresponding lens.
XJ
display can be