1. ZJ OVERHEAD CONSOLE 8C - 1
OVERHEAD CONSOLE
CONTENTS
page page
DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 SERVICE PROCEDURES . . . . . . . . . . . . . . . . . . . 8
GENERAL INFORMATION . . . . . . . . . . . . . . . . . . 1 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . 11
GENERAL INFORMATION
Two overhead consoles featuring an electronic com-
pass, thermometer, and a trip computer are available
options for Grand Cherokee models. A long version of
the overhead console is used in models without a
power sunroof option. The long overhead console in-
cludes four reading/courtesy lamps (2 front and 2
rear), a remote garage door opener storage compart-
ment, a sunglasses storage compartment, and houses
the remote keyless entry receiver.
A short version of the overhead console is used in
models with a power sunroof option. The short over-
head console includes two reading courtesy lamps
and houses the power sunroof switch. Following are
general descriptions of major components used in the
overhead console. Refer to Group 8W - Wiring Dia-
grams for complete circuit descriptions and diagrams.
TRIP COMPUTER
In addition to the thermometer/compass function,
the overhead console display can be switched to the
following trip computer readouts:
• trip odometer (ODO)
• average miles per gallon (AVG ECO)
• instant miles per gallon (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 display is turned on or off using the COMP/TEMP
will cause the overhead console display to step se- button to the left of the display.
quentially through the various display options. Input The self-calibrating compass unit requires no ad-
for the trip computer functions is received on the justing in normal use. The only calibration that may
CCD bus lines. If the data displayed is wrong, run prove necessary is to drive the vehicle in 3 complete
self-diagnostics before replacing the computer. The circles, on level ground, in not less than 48 seconds.
DRB scan tool is recommended for checking the CCD This will reorient the unit to its vehicle.
bus lines. The unit also will compensate for magnetism the
body of the vehicle may acquire during normal use.
COMPASS However, avoid placing anything magnetic directly on
The compass will display the direction in which the the roof of the vehicle. Magnetic mounts for an an-
vehicle is pointed using the eight major compass tenna, a repair order hat or a funeral procession flag
headings (Examples: north is N, northeast is NE). It can exceed the compensating ability of the compass
does not display the headings in actual degrees. The unit if placed on the roof panel. Magnetic bit drivers

2. 8C - 2 OVERHEAD CONSOLE ZJ
used on the fasteners that hold the assembly to the When all doors and the liftgate are closed, the lamps
roof header can also affect compass operation. can be individually activated by depressing the corre-
If the front console attaching screw is re- sponding lens. When a door and/or the liftgate is
placed, the new screw must be a #10 stainless open, depressing the lamp lens switches will not turn
steel. the lamps off. Refer to Group 8L - Lamps, for diag-
If the vehicle roof should become magnetized, the nosis and service of these lamps.
demagnetizing and calibration procedures may be re-
quired to restore proper operation. KEYLESS ENTRY RECEIVER
The long overhead console houses the keyless entry
THERMOMETER
receiver. Refer to Group 8P - Power Locks, for diag-
The thermometer displays the outside ambient
nosis and service of this component.
temperature. The temperature displayed can be
changed from Fahrenheit to Celsius using the US/
REMOTE GARAGE DOOR OPENER STORAGE
METRIC button. The displayed temperature is not
A compartment in the long overhead console is de-
an instant reading of conditions, but an average tem-
perature. It may take the unit several minutes to re- signed to hold most remote garage door opener trans-
act to a major temperature change such as driving mitters. The transmitter is mounted within the
out of a heated garage into winter temperatures. compartment with an adhesive-backed hook and loop
When the ignition switch is turned OFF, the last fastener patch. Then one or two pegs are selected
displayed temperature reading stays in memory. and mounted on a post on the inside of the storage
When the ignition switch is turned ON again, the compartment door. The pegs may be stacked, if nec-
thermometer will display the memory temperature essary. The peg(s) selected must be long enough to
for one minute; then update the display to the cur- activate the button of the transmitter each time the
rent average temperature reading within five min- storage compartment door is depressed.
utes.
When the vehicle is equipped with ATC, ambient SUNGLASSES STORAGE
temperature data is obtained from the HEVAC mod- A flocked storage compartment for sunglasses is in-
ule on the CCD bus lines. On vehicles without ATC, cluded in the long overhead console. This compart-
the ambient temperature sensor is hard-wired to the ment features a push/push-type latch and a viscous
trip computer. dampening system for a fluid opening motion.
READING AND COURTESY LAMPS
All reading and courtesy lamps in the overhead
console are activated by the door jamb switches.
DIAGNOSIS
Follow the appropriate diagnostic flow chart: (1) With the ignition switch in the OFF position,
• Chart 1 - Describes the procedures for compass simultaneously press and hold the STEP button and
and display problems. the US/METRIC button.
• Chart 2 - Describes the procedures for outside (2) Turn ignition switch to the ON position.
temperature measuring problems. (3) Continue to hold both buttons until the display
• Chart 3 - Describes the procedures for illumination performs a walking segment test. In this test all of
lamp problems. the compass points are displayed, along with various
number combinations. The test will:
TRIP COMPUTER/COMPASS/DISPLAY SELF- (a) Verify that all display segments are func-
DIAGNOSTIC TEST tional.
(b) Check internal circuitry.
This self-diagnostic test is used to determine that
(c) Check that all CCD bus messages needed are
the trip computer/compass and all of its display seg-
being received.
ments are operating properly electrically. It also is
If tests (a) and (b) are passed, the module will au-
used to verify that all CCD bus messages required
tomatically return to normal operation at completion
are being properly received. Initiate the self-diagnos- of tests. If any segment should fail to light during
tic test as follows: test (a), the unit is faulty and requires replacement.
If test (b) fails, the display will read FAIL. If test (c)

3. ZJ OVERHEAD CONSOLE 8C - 3
fails, the display will read CCD. Momentarily press
and release either button to exit the self-diagnostic
mode.
If the compass functions, but accuracy is sus-
pect, it may be necessary to perform a variation
adjustment. This procedure allows the unit to
accommodate variations in the earth’s mag-
netic field strength based on geographic loca-
tion. See Compass Variation Adjustment, in this
group.
If the compass display has blanked out and
only CAL appears, demagnetizing may be nec-
essary to remove excessive residual magnetic
fields from the vehicle. See Compass Demagne-
tizing, in this group.
Chart 1

4. 8C - 4 OVERHEAD CONSOLE ZJ
Chart 1 (Continued)

5. ZJ OVERHEAD CONSOLE 8C - 5
Chart 2

6. 8C - 6 OVERHEAD CONSOLE ZJ
Chart 3

7. ZJ OVERHEAD CONSOLE 8C - 7
THERMOMETER DIAGNOSIS cuit is shorted. If the temperature is below -40°C
When the vehicle is equipped with ATC, ambient (-40°F) or an open circuit exists, the system will dis-
temperature data is obtained from the HEVAC mod- play OC (open circuit).
ule on the CCD bus lines. On vehicles without ATC, To diagnose the temperature sensor, perform the
the ambient temperature sensor is hard-wired to the following procedures.
trip computer. (1) Turn the ignition switch to OFF. Unplug sensor
The thermometer function is supported by a tem- connector.
(2) Measure resistance of sensor. At -40°F the re-
perature sensor, a wiring circuit and a portion of the
sistance is 336K ohms. At 140°F the resistance is
overhead console display. The sensor is mounted to
2.488K ohms. Sensor resistance should read between
the center of the radiator support behind the grille
these two values. If OK, go to Trip Computer/Com-
(Fig. 1).
pass/Display Self-Diagnostic Test. If not OK, replace
the sensor.
Fig. 1 Temperature Sensor.
If any portion of the circuit fails, it will self-diag-
nose as an open or short circuit. The system will dis-
play SC (short circuit) when the sensor is exposed to
temperatures in excess of 55°C (131°F) or if the cir-
Fig. 2 Overhead Console Harness Connector

8. 8C - 8 OVERHEAD CONSOLE ZJ
SERVICE PROCEDURES
COMPASS VARIATION ADJUSTMENT ity of the compass. DO NOT use magnetic tools
Variance is the difference between magnetic north when servicing the overhead console.
and geographic north. In some areas, the difference
between magnetic and geographic north is great The compass features a self-calibrating design,
enough to cause the compass to give false readings. If which simplifies the calibration procedure. This fea-
this occurs, the variance must be set. ture automatically updates the compass calibration
To set the variance: while the vehicle is being driven. This takes into ac-
(1) Using the map in Fig. 3, find your geographic count small changes in residual magnetism the vehi-
location and note the zone number. cle may acquire during normal use. Do not attempt
to calibrate the compass near large metal objects
such as other vehicles, large buildings or bridges.
Whenever the compass is calibrated manually,
the variation number must also be reset. See
Variation Adjustment Procedure, in this group.
Calibrate the compass manually as follows:
(1) Start the engine.
(2) Depress both the US/METRIC and STEP but-
tons. Hold down until CAL is displayed. This takes
about 10 seconds and appears about 5 seconds after
VAR is displayed.
(3) Release both buttons.
(4) Drive vehicle on a level surface that is away
from large metal objects through 3 or more complete
circles in not less than 48 seconds. The CAL message
will disappear to indicate that the compass is now
calibrated.
If CAL message remains in display, either
there is excessive magnetism near the compass
or the unit is faulty. Repeat the demagnetizing
and calibration procedures at least one more
time.
If the wrong direction is still indicated, the
area selected may be too close to a strong mag-
netic field. Repeat the calibration procedure in
another location.
COMPASS DEMAGNETIZING
Fig. 3 Variance Settings The tool used to degauss or demagnetize the for-
(2) Turn ignition switch to the ON position. ward console attaching screw and roof panel is the
(3) Depress both the US/METRIC and STEP but- Miller Tool 6029. Equivalent units must be rated as
tons. Hold down until VAR is displayed. This takes continuous duty for 110/115 volts and 60Hz. They
about 5 seconds. must also have a field strength of over 350 gauss at
(4) Release both buttons. 1/4-inch beyond the tip of the probe.
(5) Press the US/METRIC button to step through The degaussing tool is used to demagnetize both
the numbers until the zone number for your area ap- the roof panel and the console forward mounting
pears in the display. screw, as follows:
(6) Press the STEP button to enter this zone num- (1) Be sure the ignition switch is in the OFF posi-
ber into compass unit memory. tion before you begin the demagnetizing procedure.
(7) Confirm correct directions are indicated. (2) Plug in the degaussing tool, while keeping the
tool at least 2 feet away from the compass unit.
COMPASS CALIBRATION (3) Slowly approach the head of the forward
mounting screw with the plastic coated tip of the de-
CAUTION: DO NOT place any external magnets gaussing tool. Contact the head of the screw for
such as magnetic roof mount antennas, in the vicin- about 2 seconds.

9. ZJ OVERHEAD CONSOLE 8C - 9
(4) With the degaussing tool still energized, slowly AMBIENT TEMPERATURE SENSOR REMOVE/
back it away from the screw until the tool is at least INSTALL
2 feet from the screw head, then unplug the tool. (1) Remove the radiator grille (Fig. 5).
(5) Place an 8-1/2 X 11 inch piece of paper, oriented
lengthwise from front to rear, on the center line of
the roof at the windshield header (Fig. 4). The pur-
pose of the paper is to protect the roof panel from
scratches and define the area to be demagnetized.
Fig. 5 Radiator Grille Remove/Install
(2) Disconnect sensor wiring connector (Fig. 6).
Fig. 4 Roof Demagnetizing Pattern
Fig. 6 Ambient Temperature Sensor Remove/Install
(6) Plug in the degaussing tool, while keeping the
tool at least 2 feet away from the compass unit. (3) Remove sensor mounting bolt and remove sen-
(7) Slowly approach the center line of the roof sor.
panel at the windshield header with the degaussing (4) Reverse removal procedures to install.
tool plugged in.
(8) Contact the roof panel with the tip of the tool. OVERHEAD CONSOLE REMOVE/INSTALL
Be sure template is in place to avoid scratching the
LONG STYLE
roof panel. Using a slow, back and forth sweeping
(1) Remove console forward mounting screw (Fig.
motion and allowing 1/2-inch between passes (Fig. 4),
7).
move the tool at least 4 inches either side of the roof
(2) Slide console forward until the console detaches
center line and 11 inches back from the windshield
from the rear mounting bracket.
header.
(3) Disconnect wire harnesses from keyless entry
(9) With the degaussing tool still energized, slowly
receiver and trip computer (Fig. 8).
back it away from the roof panel until the tip is at
(4) Reverse removal procedures to install.
least 2 feet from the roof. Then unplug the tool.
(10) Calibrate the compass and adjust variance as SHORT STYLE
described in this group. (1) Remove console forward mounting screw (Fig.
9).

10. 8C - 10 OVERHEAD CONSOLE ZJ
Fig. 7 Long Overhead Console Remove/Install Fig. 9 Short Overhead Console Remove/Install
Fig. 8 Keyless Entry Harness Connector
(2) Gently pry downwards at rear of console to re-
lease 2 snap clips.
(3) Disconnect wire harnesses from trip computer
and power sunroof switch.
(4) Reverse removal procedures to install.
Fig. 10 Trip Computer Remove/Install
TRIP COMPUTER REMOVE/INSTALL PUSH-BUTTON MODULE REMOVE/INSTALL
(1) Remove overhead console and disconnect wir- (1) Remove overhead console and disconnect wir-
ing. See Overhead Console Remove/Install. ing. See Overhead Console Remove/Install.
(2) Unplug harness connector from trip computer. (2) Unplug harness connectors from push-button
(3) Remove 2 screws holding trip computer to con- module.
sole (Fig. 10). (3) Remove 4 screws holding module to console
(4) Spread retaining tabs on the sides to remove (Fig. 10).
trip computer from the console. (4) Remove module from console.
(5) Reverse removal procedures to install. (5) Reverse removal procedures to install.

11. ZJ OVERHEAD CONSOLE 8C - 11
READING/COURTESY LAMP BULB REMOVE/ (3) Install new bulb by pushing firmly into socket.
INSTALL (4) Pivot lens up into position and snap in. Test by
(1) Insert a long flat-bladed tool at the notch on pressing lens for proper operation and lighting.
the curved edge of the lens. Carefully pry the lens
from the housing and pivot the lens down. It may be KEYLESS ENTRY RECEIVER
necessary to move the tool along the edge to free the Refer to Group 8P - Power Locks for service of this
lens. component.
(2) Remove bulb by pulling straight down.
SPECIFICATIONS
TRIP COMPUTER FUEL SENDER
CALIBRATION