repair procedures, details of wire harness routing
and retention, connector pin-out information and
location views for the various wire harness connec-
tors, splices and grounds.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the instrument panel wire harness con-
nector for the park brake switch from the park brake
switch terminal. Apply the parking brake. Check for
continuity between the park brake switch terminal
and a good ground. There should be continuity. If
OK, go to Step 2. If not OK, replace the faulty park
brake switch.
(2) Remove the instrument cluster and disconnect
the instrument panel wire harness connector for the
instrument cluster from the cluster connector recep-
tacle. Check for continuity between the red brake
warning indicator driver circuit cavity of the instru-
ment panel wire harness connector for the instru-
ment cluster and a good ground. There should be no
continuity. If OK, go to Step 3. If not OK, repair the
shorted red brake warning indicator driver circuit
between the park brake switch and the instrument
cluster as required.
(3) Check for continuity between the red brake
warning indicator driver circuit cavities of the instru-
ment panel wire harness connectors for the instru-
ment cluster and the park brake switch. There
should be continuity. If not OK, repair the open red
brake warning indicator driver circuit between the
park brake switch and the instrument cluster as
required.
CHECK GAUGES INDICATOR
DESCRIPTION
A check gauges indicator lamp is standard equip-
ment on all instrument clusters. The check gauges
indicator lamp is located on the right edge of the
instrument cluster overlay, between the oil pressure
gauge and the coolant temperature gauge. The check
gauges indicator lamp consists of a the words
“CHECK GAGES” imprinted on a red lens located
behind a cutout in the opaque layer of the instru-
ment cluster overlay. The dark outer layer of the
overlay prevents the indicator from being clearly vis-
ible when the lamp is not illuminated. The words
“CHECK GAGES” appear silhouetted against a red
field through the translucent outer layer of the over-
lay when the indicator is illuminated from behind by
a replaceable incandescent bulb and bulb holder unit
located on the instrument cluster electronic circuit
board. The check gauges indicator lens is serviced as
a unit with the instrument cluster lens, hood and
mask unit.
OPERATION
The check gauges indicator lamp gives an indica-
tion to the vehicle operator when certain instrument
cluster gauge readings reflect a condition requiring
immediate attention. This lamp is controlled by a
transistor on the instrument cluster circuit board
based upon the cluster programming and electronic
messages received by the cluster from the Powertrain
Control Module (PCM) over the Programmable Com-
munications Interface (PCI) data bus. The check
gauges indicator lamp bulb receives battery current
on the instrument cluster electronic circuit board
through the fused ignition switch output (st-run) cir-
cuit whenever the ignition switch is in the On or
Start positions; therefore, the lamp will always be off
when the ignition switch is in any position except On
or Start. The lamp bulb only illuminates when it is
provided a path to ground by the instrument cluster
transistor. The instrument cluster will turn on the
check gauges indicator lamp for the following rea-
sons:
• Bulb Test - Each time the ignition switch is
turned to the On position the lamp is illuminated for
about three seconds.
• Engine Temperature High Message - Each
time the cluster receives a message from the PCM
indicating the engine coolant temperature is about
124° C or higher (about 255° F or higher), the lamp
will be illuminated. The lamp remains illuminated
until the cluster receives a message from the PCM
indicating that the engine temperature is about 122°
C or lower (about 252° F or lower), or until the igni-
tion switch is turned to the Off position, whichever
occurs first.
• Engine Oil Pressure Low Message - Each
time the cluster receives a message from the PCM
indicating the engine oil pressure is about 0.003
kg/cm or lower (about 6 psi or lower), the lamp will
be illuminated. The lamp remains illuminated until
the cluster receives a message from the PCM indicat-
WG
INSTRUMENT CLUSTER
8Js - 11
BRAKE/PARK BRAKE INDICATOR (Continued)
2001 JEEP GRAND CHEROKEE