ACTUATOR TEST
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.
The instrument cluster actuator test will put the
instrument cluster into its self-diagnostic mode. In
this mode the instrument cluster can perform a self-
diagnostic test that will confirm that the instrument
cluster circuitry, the gauges, and the PCI data bus
message controlled indicator lamps are capable of
operating as designed. During the actuator test the
instrument cluster circuitry will sweep each of the
gauge needles across the gauge faces, illuminate each
of the segments in the Vacuum-Fluorescent Display
(VFD), and turn all of the PCI data bus message-con-
trolled lamps on and off.
Successful completion of the actuator test will con-
firm that the instrument cluster is operational. How-
ever, there may still be a problem with the PCI data
bus, the Airbag Control Module (ACM), the Body
Control Module (BCM), the Controller Anti-lock
Brake (CAB), the Sentry Key Immobilizer Module
(SKIM), or the inputs to one of these electronic con-
trol modules. Use a DRBIII
t scan tool to diagnose
these components. Refer to the appropriate diagnos-
tic information.
If an individual gauge does not respond properly,
or does not respond at all during the actuator test,
the instrument cluster should be removed. However,
check that the mounting tabs securing the inopera-
tive gauge or gauge set to the instrument cluster
electronic circuit board are properly installed and
making good contact with the instrument cluster
electronic circuit board before considering gauge
replacement. If the gauge mounting tabs check OK,
replace the faulty gauge or gauge set.
If an individual indicator lamp does not illuminate
during the actuator test, the instrument cluster
should be removed. However, check that the incan-
descent lamp bulb is not faulty and that the bulb
holder is properly installed on the instrument cluster
electronic circuit board before considering instrument
cluster housing and circuit board replacement. If the
bulb and bulb holder check OK, replace the faulty
instrument cluster housing and circuit board unit.
If any or all segments of the VFD fail to illuminate
during the actuator test, the VFD or the instrument
cluster electronic circuit board is faulty or damaged.
The instrument cluster housing and circuit board
unit must be replaced.
(1) Begin the test with the ignition switch in the
Off position.
(2) Depress the odometer/trip odometer switch but-
ton.
(3) While still holding the odometer/trip odometer
switch button depressed, turn the ignition switch to
the On position, but do not start the engine.
(4) Release the odometer/trip odometer switch but-
ton.
(5) Monitor the operation of the suspect gauge(s)
and/or indicator lamp(s).
(6) The instrument cluster will automatically exit
the self-diagnostic mode and return to normal opera-
tion at the completion of the test, if the ignition
switch is turned to the Off position during the test,
or if a vehicle speed message indicating that the
vehicle is moving is received from the PCM over the
PCI data bus during the test.
(7) Go back to Step 1 to repeat the test, if
required.
CLUSTER ILLUMINATION DIAGNOSIS
The EMIC has several illumination lamps that are
illuminated whenever the exterior lighting is turned
On. The illumination intensity of these bulbs and of
the vacuum-fluorescent electronic display are con-
trolled by the instrument cluster microprocessor
based upon dimming messages received from the
Body Control Module (BCM) over the PCI data bus.
The BCM uses inputs from the headlamp and panel
dimmer switches on the left (lighting) multi-function
switch control stalk and internal programming to
decide what dimming message is required. The BCM
then sends the proper dimming messages to the
EMIC over the PCI data bus. The illumination lamps
receive battery current through the EMIC electronic
circuit board, and are grounded at all times. The left
(lighting) multi-function switch and the hard wired
inputs it provides to the BCM can be tested using
conventional diagnostic tools and methods. (Refer to
8 - ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
HEADLAMP SWITCH - DIAGNOSIS AND TEST-
ING). Proper testing of the cluster illumination
lamps, the VFD dimming level, the BCM, and the
PCI data bus dimming level messages requires the
use of a DRBIII
t scan tool. Refer to the appropriate
diagnostic information.
WG
INSTRUMENT CLUSTER
8Js - 7
INSTRUMENT CLUSTER (Continued)
2001 JEEP GRAND CHEROKEE