Jeep 1997 Grand Cherokee Service Manual page 605

ZG
SERVICE PROCEDURES (Continued)
NOTE: Whenever the compass is calibrated manu-
ally, the variation number must also be reset. See
the Compass Variation Adjustment procedure, in
this group.
Calibrate the compass manually as follows:
(1) Start the engine. If the compass/temperature
data is not currently being displayed, momentarily
depress and release the Step button to step through
the display options until you have reached the com-
pass/temperature display.
(2) Depress both the U.S./Metric, and the Step but-
tons. Hold the buttons down until "CAL" appears in
the display. This takes about ten seconds, and
appears about five seconds after "VAR" is displayed.
(3) Release both of the buttons.
(4) Drive the vehicle on a level surface, away from
large metal objects, through three or more complete
circles in not less than 48 seconds. The "CAL" mes-
sage will disappear from the display to indicate that
the compass is now calibrated.
NOTE: If the "CAL" message remains in the dis-
play, either there is excessive magnetism near the
compass, or the unit is faulty. Repeat the demagne-
tizing and calibration procedures at least one more
time.
NOTE: If the wrong direction is still indicated in the
compass display, the area selected for calibration
Fig. 1 Variance Settings
may be too close to a strong magnetic field. Repeat
the calibration procedure in another location.
COMPASS DEMAGNETIZING
A degaussing tool (Special Tool 6029) is used to
demagnetize, or degauss, the overhead console for-
ward mounting screw and the roof panel. Equivalent
units must be rated as continuous duty for 110/115
volts and 60 Hz. They must also have a field
strength of over 350 gauss at 7 millimeters (0.25
inch) beyond the tip of the probe.
To demagnetize the roof panel and the overhead
console forward mounting screw, proceed as follows:
(1) Be certain the ignition switch is in the Off posi-
tion, before you begin the demagnetizing procedure.
(2) Plug in the degaussing tool, while keeping the
tool at least 61 centimeters (2 feet) away from the
compass unit.
(3) Slowly approach the head of the overhead con-
sole forward mounting screw with the degaussing
tool plugged in.
(4) Contact the head of the screw with the plastic
coated tip of the degaussing tool for about two sec-
onds.
(5) With the degaussing tool still energized, slowly
back it away from the screw. When the tip of the tool
is at least 61 centimeters (2 feet) from the screw
head, unplug the tool.
OVERHEAD CONSOLE SYSTEMS 8V - 5