Graphic Display Module - Jeep 1997 Grand Cherokee Service Manual

8E - 14 INSTRUMENT PANEL SYSTEMS
DIAGNOSIS AND TESTING (Continued)
8H - Vehicle Speed Control and/or to the proper Pow-
ertrain Diagnostic Procedures manual for diagnosis.
For circuit descriptions and diagrams, refer to 8W-33
- Vehicle Speed Control and 8W-40 - Instrument
Cluster in Group 8W - Wiring Diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO GROUP 8M - PASSIVE RESTRAINT
SYSTEMS BEFORE ATTEMPTING STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL COM-
PONENT DIAGNOSIS OR SERVICE. FAILURE TO
TAKE THE PROPER PRECAUTIONS COULD RESULT
IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
If the cruise-on indicator lamp fails to light during
the bulb test (about four seconds after the ignition
switch is turned to the On position), replace the
cruise-on indicator lamp bulb with a known good
unit. If the cruise-on lamp still fails to operate, diag-
nosis of the lamp, the instrument cluster circuitry,
and the CCD data bus should be performed with a
DRB scan tool as described in the proper Body Diag-
nostic Procedures manual. Diagnosis of the speed
control switches and circuits and/or Powertrain Con-
trol Module (PCM) should be performed with a DRB
scan tool as described in the proper Powertrain Diag-
nostic Procedures manual.

GRAPHIC DISPLAY MODULE

If the problem being diagnosed is related to
Graphic Display Module (GDM) illumination, see the
GDM Illumination diagnosis below. If the problem
being diagnosed is related to the four-wheel drive
display or four-wheel drive message lamps, see the
Four-Wheel Drive Indicator Lamp diagnosis below.
Refer to 8W-46 - Message Center in Group 8W - Wir-
ing Diagrams for complete circuit descriptions and
diagrams.
GDM ILLUMINATION
The diagnosis found here addresses an inoperative
illumination lamp condition. If the problem being
diagnosed is related to the dimming level of the illu-
mination lamps, diagnosis should be performed with
a DRB scan tool as described in the proper Body
Diagnostic Procedures manual.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO GROUP 8M - PASSIVE RESTRAINT
SYSTEMS BEFORE ATTEMPTING STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL COM-
PONENT DIAGNOSIS OR SERVICE. FAILURE TO
TAKE THE PROPER PRECAUTIONS COULD RESULT
IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
If only individual illumination lamps are inopera-
tive, replace the faulty bulbs. If all of the illumina-
tion lamps are inoperative, proceed as follows.
(1) Disconnect and isolate the battery negative
cable. Remove the GDM as described in this group.
Unplug the GDM wire harness connector and connect
the battery negative cable.
(2) Turn the park lamps on with the headlamp
switch. Adjust the panel lamp dimmer switch knob to
its highest level (fully upwards). Check for voltage at
the panel lamp driver circuit cavity of the GDM wire
harness connector. If OK, replace the faulty GDM. If
not OK, go to Step 3.
(3) Disconnect and isolate the battery negative
cable. Unplug the white 24-way Body Control Module
(BCM) wire harness connector. Check for continuity
between the panel lamp driver circuit cavities of the
GDM wire harness connector and the BCM wire har-
ness connector. If OK, refer to Group 8L - Lamps for
diagnosis of the headlamp switch and/or the proper
Body Diagnostic Procedures manual for diagnosis of
the BCM. If not OK, repair the open circuit as
required.
FOUR-WHEEL DRIVE INDICATOR LAMP
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO GROUP 8M - PASSIVE RESTRAINT
SYSTEMS BEFORE ATTEMPTING STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL COM-
PONENT DIAGNOSIS OR SERVICE. FAILURE TO
TAKE THE PROPER PRECAUTIONS COULD RESULT
IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
(1) Unplug the wire harness connector at the
transfer case switch. Check for continuity between
the ground circuit cavity of the transfer case switch
wire harness connector and a good ground. There
should be continuity. If OK, go to Step 2. If not OK,
repair the open circuit as required.
(2) Check the transfer case switch continuity while
shifting the transfer case shift lever to the proper
positions. The switch continuity should be as shown
in (Fig. 1). If OK, go to Step 3. If not OK, replace the
faulty switch.
(3) Disconnect and isolate the battery negative
cable. Remove the GDM as described in this group.
Unplug the GDM wire harness connector.
(4) Check the continuity of the circuit for the indi-
cator lamp or wheel lamp that is not functioning
between the GDM wire harness connector and the
transfer case switch wire harness connector. There
should be continuity. If OK, go to Step 5. If not OK,
repair the open circuit as required.
(5) Replace the bulb for the inoperative indicator
lamp or wheel lamp. Plug in the GDM and transfer
ZG