Jeep 1996 Grand Cherokee Service Manual page 460

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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
option is not being displayed, momentarily depress
and release the Step button through the display
options until you have reached the compass/tempera-
ture display.
(2) Depress both the U.S./Metric and Step buttons.
Hold down both buttons until "CAL" appears in the
display module. This takes about ten seconds, and
appears about five seconds after "VAR" is displayed.
(3) Release both 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
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 front
mounting screw and the roof panel. Equivalent units
must be rated as continuous duty for 110/115 volts
and 60Hz. They must also have a field strength of
over 350 gauss at 1/4-inch beyond the tip of the
probe.
To demagnetize the roof panel and the console for-
ward 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 two feet away from the compass unit.
(3) Slowly approach the head of the overhead con-
sole front mounting screw with the plastic coated tip
of the degaussing tool. Contact the head of the screw
with the tip of the tool for about two seconds.
(4) With the degaussing tool still energized, slowly
back it away from the screw. When the tool is at
least two feet from the screw head, unplug the tool.
OVERHEAD CONSOLE SYSTEMS
(5) Place an 8-1/2 X 11-inch piece of paper, ori-
ented on the vehicle lengthwise from front to rear, on
the center line of the roof at the windshield header
(Fig. 2). The purpose of the paper is to protect the
roof panel from scratches, and to define the area to
be demagnetized.
Fig. 2 Roof Demagnetizing Pattern
(6) Plug in the degaussing tool, while keeping the
tool at least two feet away from the compass unit.
(7) Slowly approach the center line of the roof
panel at the windshield header, with the degaussing
tool plugged in.
(8) Contact the roof panel with the tip of the tool.
Be sure the template is in place to avoid scratching
the roof panel. Using a slow, back-and-forth sweeping
motion, and allowing 1/2-inch between passes, move
the tool at least four inches to each side of the roof
center line, and eleven inches back from the wind-
shield header.
(9) With the degaussing tool still energized, slowly
back it away from the roof panel. When the tip of the
tool is at least two feet from the roof panel, unplug
the tool.
(10) Calibrate the compass and adjust the compass
variance as described in this group.
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